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University of Veterinary Medicine Hannover
Influence of raw material and weaning management on the
occurrence of tail-biting in undocked pigs
INAUGURAL–DISSERTATION
in partial fulfillment of the requirements of the degree of
Doctor of Veterinary Medicine
-Doctor medicinae veterinariae-
(Dr. med. vet.)
submitted by
Christina Veit
Neunkirchen/ Saar
Hannover 2016
Academic supervision: 1. Prof. Dr. Elisabeth grosse Beilage
Field Station for Epidemiology (Bakum)
University of Veterinary Medicine
Hannover, Germany
2. Prof. Dr. Joachim Krieter
Institute of Animal Breeding and Husbandry
Christian-Albrechts-University
Kiel, Germany
1. Referee: Prof. Dr. Elisabeth grosse Beilage
Field Station for Epidemiology (Bakum)
University of Veterinary Medicine
Hannover, Germany
2. Referee: Prof. Dr. Karl-Heinz Waldmann
Clinic for Swine and Small Ruminants,
Forensic Medicine and Ambulatory Services
University of Veterinary Medicine
Hannover, Germany
Day of the oral examination: 03.05.2016
Meiner Familie
Christina Veit: Influence of raw material and weaning management on the occurrence
of tail-biting in undocked pigs
TABLE OF CONTENTS
GENERAL INTRODUCTION………………………………………………………………...1
LITERATURE REVIEW
Literaturübersicht zur Verhaltensstörung “Schwanzbeißen” beim Schwein……………….….6
MATERIAL AND METHODS………………………………………………………………29
CHAPTER ONE
Influence of raw material on the occurrence of tail-biting in undocked pigs……..……….....41
CHAPTER TWO
The effect of mixing after weaning on tail-biting during rearing with characterisation of
performers and receivers of manipulative behavioral patterns……………………………….61
GENERAL DISCUSSION…………………………………………………………..……….83
GENERAL SUMMARY……………………………………………………………..………93
ZUSAMMENFASSUNG………………………………………………………………….....96
1
GENERAL INTRODUCTION
Tail-biting in pigs is a widespread behavioural disorder in intensive pig husbandry with
multifactorial causes. Three different forms are known: “two-stage biting”, “sudden forceful
biting” as well as “obsessive biting” (Taylor et al., 2010). The differences are determined on
one hand by the manner of expression and on the other hand by the causes associated with
this behaviour. Generally, tail-biting is defined as injury to the tail in different degrees of
severity through manipulations with the mouth. Tail-docking, which has so far been classified
as the safest measure to reduce this behavioural disorder, is forbidden according to European
law (2001/ 93/ EG) and does not solve the underlying mechanisms. The possible risks which
can bring about tail-biting are environmental factors such as a lack of rooting substrate
(Zonderland et al., 2008), poor ventilation (Hunter et al., 2001), higher stocking densities and
deficiencies in feed quality or accessibility (Moinard et al., 2003), as well as group size and
group composition (Zonderland et al., 2010). On the biological side, poor health (Day et al.,
2002), breed (Breuer et al., 2003) and gender (Zonderland et al., 2010) could play a role in the
development of the behavioural disorder. Depending on the individual circumstances
encountered on farms, different stressors influence the animals and require them to activate
their coping ability. An overextension of the adaptive capacity may trigger tail-biting. The
possible consequences of tail-biting are a reduction in animal welfare due to pain, infection
and lameness, as well as economic losses due to reduced carcass qualities (Harley et al., 2014;
Huey, 1996).
The need to perform exploration and foraging behaviour is considered to be a major
underlying motivation for tail-biting. When suitable material is unavailable, pigs may redirect
their exploratory behaviour towards other pigs and pen surroundings (EFSA, 2007). Several
studies have shown a reduction in tail-biting through environmental enrichment with straw
(Day et al., 2008; Van de Weerd et al., 2006) or other material which can be rooted (Sneddon
et al., 2001). Environmental enrichment reduces time spent involved in harmful social and
aggressive behaviour (Beattie et al., 2000). Pigs in barren environments often show higher
frequencies of manipulating floor and walls, nudging litter mates and tail-biting litter mates
than pigs in enriched conditions (Petersen et al., 1995). Rooting materials for pigs should
meet the requirements of their natural exploratory behaviour, which includes rooting, sniffing,
biting and chewing (Studnitz et al., 2007). Manipulation is therefore an important aspect of
2
stimulation and emphasises the importance of the characteristics “ingestible”, “chewable”,
“deformable” and “destructible“ for suitable material (Van de Weerd et al., 2003).
Another feature of tail-biting is the period in which it occurs, which in long-tailed piglets is
mainly the rearing phase. A temporal connection between the occurrence of the behavioural
disorder and the weaning process has already been identified (Abriel and Jais, 2013). Pigs in
intensive husbandry today are faced with several challenges. The most massive break in the
piglets’ life cycle is the weaning process i.e. separation from the sow, which is usually
accompanied by a change in housing environment and diet. Furthermore, sorting of litters by
size and gender, i.e. the mixing of unacquainted conspecifics is usual management process.
Environmental factors which disturb the normal hierarchy can result in frustration and
aggression (Schrøder-Petersen and Simonsen, 2001) and may, in turn, increase the risk of tail-
biting. According to Hötzel et al. (2011), the mixing of litters implicates higher frequencies of
agonistic and exploratory behaviours, lower resting frequencies and a higher proportion of
severe skin lesions. Although the effect of social status and events such as mixing on tail-
biting have received limited attention, mixing may act to trigger tail-biting under commercial
conditions (EFSA, 2007).
The aim of the present thesis was to adapt housing conditions in pig husbandry in order to
enable piglets to perform their natural behavioural patterns such as exploration and rooting.
The required measures were implemented under practical conditions without strong
interventions in the management process on the farms. Focus was given to the provision of
raw material and the avoidance of stress through regrouping after weaning. Furthermore,
information about pigs’ activity behaviour and occupation with the material provided was
obtained by video observation. The present thesis consists of three parts, a literature review, a
study on environmental enrichment (Chapter One) and a study on weaning management
(Chapter Two).
The literature review highlights the different forms of tail-biting, the legal foundations for
docking, the risk factors for the behavioural disorder and possible indicators for an upcoming
outbreak.
The main issue of Chapter One is the provision of manipulable material (alfalfa hay and corn
silage) for undocked pigs and its influence on the development of tail-biting. Another aspect
represents the activity behaviour of the piglets analysed by video observations.
3
Chapter Two emphasises the effect of mixing on tail-biting during rearing. Furthermore,
performers and receivers of manipulative behavioural patterns are characterised regarding
their behaviour five days prior to a tail-biting outbreak and on the day of an outbreak itself.
Conclusions to be drawn concerning the measures, the provision of raw material and the
avoidance of mixing after weaning in order to prevent tail-biting are discussed
comprehensively.
References
2001/ 93/ EG. Richtlinie 2001/ 93/ EG der Kommission vom 9. November 2001 zur
Änderung der Richtlinie 91/ 630/ EWG über Mindestanforderungen für den Schutz
von Schweinen.
Abriel, M., and C. Jais. 2013. Influence of housing conditions on the appearance of
cannibalism in weaning piglets. Landtechnik 68: 389-393.
Beattie, V. E., N. E. O'Connell, and B. W. Moss. 2000. Influence of environmental
enrichment on the behaviour, performance and meat quality of domestic pigs.
Livestock Production Science 65: 71-79.
Breuer, K. et al. 2003. The effect of breed on the development of adverse social behaviours in
pigs. Applied Animal Behaviour Science 84: 59-74.
Day, J. E. L. et al. 2002. The effects of prior experience of straw and the level of straw
provision on the behaviour of growing pigs. Applied Animal Behaviour Science 76:
189-202.
Day, J. E. L., H. A. Van de Weerd, and S. A. Edwards. 2008. The effect of varying lengths of
straw bedding on the behaviour of growing pigs. Applied Animal Behaviour Science
109: 249-260.
EFSA. 2007. Scientific report on the risks associated with tail biting in pigs and possible
means to reduce the need for tail docking considering the different housing and
husbandry systems. The EFSA Journal 611: 1-13.
Harley, S. et al. 2014. Docking the value of pigmeat? Prevalence and financial implications of
welfare lesions in irish slaughter pigs. Animal Welfare 23: 275-285.
Hötzel, M. J., G. P. P. de Souza, O. A. D. Costa, and L. C. P. Machado Filho. 2011.
Disentangling the effects of weaning stressors on piglets' behaviour and feed intake:
4
Changing the housing and social environment. Applied Animal Behaviour Science
135: 44-50.
Huey, R. J. 1996. Incidence, location and interrelationships between the sites of abscesses
recorded in pigs at a bacon factory in northern ireland. The Veterinary record 138:
511-514.
Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 2001. The relationship
between tail biting in pigs, docking procedure and other management practices. The
Veterinary Journal 161: 72-79.
Moinard, C., M. Mendl, C. J. Nicol, and L. E. Green. 2003. A case control study of on-farm
risk factors for tail biting in pigs. Applied Animal Behaviour Science 81: 333-355.
Petersen, V., H. B. Simonsen, and L. G. Lawson. 1995. The effect of environmental
stimulation on the development of behaviour in pigs. Applied Animal Behaviour
Science 45: 215-224.
Schrøder-Petersen, D. L., and H. B. Simonsen. 2001. Tail biting in pigs. The Veterinary
Journal 162: 196-210.
Sneddon, I. A., V. E. Beattie, N. Walker, and R. N. Weatherup. 2001. Environmental
enrichment of intensive pig housing using spent mushroom compost. Animal Science
72: 35-42.
Studnitz, M., M. B. Jensen, and L. J. Pedersen. 2007. Why do pigs root and in what will they
root?: A review on the exploratory behaviour of pigs in relation to environmental
enrichment. Applied Animal Behaviour Science 107: 183-197.
Taylor, N. R., D. C. J. Main, M. Mendl, and S. A. Edwards. 2010. Tail-biting: A new
perspective. The Veterinary Journal 186: 137-147.
Van de Weerd, H. A., C. M. Docking, J. E. L. Day, P. J. Avery, and S. A. Edwards. 2003. A
systematic approach towards developing environmental enrichment for pigs. Applied
Animal Behaviour Science 84: 101-118.
Van de Weerd, H. A. V. d., C. M. Docking, J. E. L. Day, K. Breuer, and S. A. Edwards. 2006.
Effects of species-relevant environmental enrichment on the behaviour and
productivity of finishing pigs. Applied Animal Behaviour Science 99: 230-247.
5
Zonderland, J. J., M. B. M. Bracke, L. A. den Hartog, B. Kemp, and H. A. M. Spoolder. 2010.
Gender effects on tail damage development in single- or mixed-sex groups of weaned
piglets. Livestock Science 129: 151-158.
Zonderland, J. J. et al. 2008. Prevention and treatment of tail biting in weaned piglets.
Applied Animal Behaviour Science 110: 269-281.
6
LITERATURE REVIEW
Literaturübersicht zur Verhaltensstörung „Schwanzbeißen“ beim Schwein
Review of the behavioural disorder tail-biting in pigs
Christina Veit1, Elisabeth große Beilage², Joachim Krieter1
1Institut für Tierzucht und Tierhaltung, Christian-Albrechts-Universität, Kiel
2Außenstelle für Epidemiologie, Stiftung Tierärztliche Hochschule, Hannover
Originalpublikation:
Veit C, grosse Beilage E, Krieter J (2016): Literaturübersicht zur Verhaltensstörung
Schwanzbeißen beim Schwein. Prakt Tierarzt 97(3): 232–241, Schlütersche, Hannover.
7
Zusammenfassung
Schwanzbeißen beim Schwein ist eine Verhaltensstörung mit multifaktoriellen Ursachen, die
seit der Intensivierung der Nutztierhaltung auftritt. Drei verschiedene Formen sind bekannt:
„zweistufiges Beißen“, „plötzliches gewaltsames Beißen“ und „obsessives Beißen“. Die
Unterschiede liegen zum einen in der Art und Weise der Ausübung des Verhaltens und zum
anderen in den Ursachen, die diesem Verhalten zugrunde liegen. Schwanzbeißen ist definiert
als das Verletzen des Schwanzes durch Manipulation mit dem Maul in unterschiedlichen
Schweregraden. Das Kupieren der Schwänze, welches bisher als sicherste Maßnahme zur
Verminderung der Verhaltensstörung gilt, ist laut EU-Gesetzgebung und deutschem
Tierschutzgesetz verboten und behebt die zugrundeliegenden Ursachen nicht. Mögliche
Risikofaktoren für Schwanzbeißen sind neben umweltbedingten Faktoren wie z. B.
mangelnde Beschäftigung, Absetzmanagement, Klima/ Lüftung, Fütterung, Belegdichte,
Gruppengröße und Gruppenzusammensetzung, auch tierspezifische Faktoren wie z. B.
Gesundheitszustand, Genetik und Geschlecht. Je nach Betriebssituation wirken
unterschiedliche Stressoren auf die Tiere ein, die bei Überschreitung ihrer
Anpassungsfähigkeit zur Auslösung der Verhaltensstörung führen können. Folgen des
Schwanzbeißens sind neben Verminderung des Tierwohls durch Schmerzen, Leiden und
Schäden auch wirtschaftliche Einbußen durch reduzierte Schlachtkörperqualitäten. Die
Haltungsbedingungen müssen dahingehend verändert werden, dass die Stressbelastung für die
Tiere (u. a. durch Verhinderung des Ausübens angeborener Verhaltensweisen) reduziert wird.
Die vorliegende Arbeit gibt eine Übersicht über den Stand der Forschung und mögliche
Lösungsansätze zur Problematik des Schwanzbeißens.
Summary
Tail-biting in pigs is a behavioural disorder with multifactorial causes which occurs since the
intensification of farm animal production. Three different forms are known: “two-stage
biting”, “sudden forceful biting” and “obsessive biting”. Differences exist in the manner of
how the behaviour is expressed, as well as in the underlying causes. Generally, tail-biting is
defined as injury to the tail of different degrees of severity through manipulations with the
mouth. The docking of tails, which has been hitherto classified as the best measure to prevent
tail lesions, is forbidden according to European and German law and does not solve the
8
underlying problems. Possible risk factors for tail-biting are on one hand environmental
factors, such as insufficient enrichment, weaning management, climate/ ventilation, feeding,
stocking density, group size and group composition, and on the other hand animal-specific
factors, such as health status, genetic and gender. Depending on the particular farm situation,
the pigs are influenced by different stressors which can trigger the behavioural disorder in
case of overtaxed coping abilities. In addition to a reduction of animal welfare through pain,
suffering and injuries, the consequences of tail-biting also include economical losses through
reduced carcass quality. The housing conditions must be changed in a way that the stress level
for the animals (e. g. through avoidance of expression of natural behaviours) is reduced. The
present review provides an overview of the state of research and possible solution strategies
for the issue of tail-biting.
9
Einleitung
Schwanzbeißen ist eine weit verbreitete Verhaltensstörung in der intensiven Schweinehaltung,
die ein eingeschränktes Tierwohl und wirtschaftliche Einbußen zur Folge hat (EFSA, 2007).
Die Prävalenz von Schwanzverletzungen wurde bisher überwiegend durch Erhebungen am
Schlachthof ermittelt und liegt in den europäischen Ländern bei kupierten Tieren im Mittel
bei 3 % und bei unkupierten Tieren bei 6-10 % bis hin zu 30 % (EFSA, 2007). Bei der
Bewertung der Prävalenzschätzungen an kupierten Tieren ist allerdings zu bedenken, dass die
Erhebung das Problem möglicherweise unterschätzt, da abgeheilte Verletzungen an kupierten
Schwänzen oft nicht mehr als solche erkannt werden. Die tatsächliche Prävalenz in den
Betrieben kann von den am Schlachthof erhobenen Daten zudem abweichen, da die
Abgangsraten aufgrund von Schwanzverletzungen nicht berücksichtigt werden können
(EFSA, 2007).
Die gesundheitlichen Beeinträchtigungen durch Schwanzbeißen ergeben sich aus der
Verletzung selbst, in einigen Fällen aber auch durch Infektionen, die aufsteigend bei
Erreichen des Rückenmarkes zur Abszessbildung mit nachfolgender Hinterhandlähmung
führen bzw. nach einem Eindringen der Keime eine Pyämie verursachen (Huey, 1996). Die
Keimansiedlung und Abszessbildung im Körper führen dazu, dass vermehrt Schlachtkörper
verworfen werden müssen, was wirtschaftliche Schäden zur Folge hat (Harley et al., 2014).
Außerdem sind die Zunahmen bei den Opfern von Schwanzbeißen geringer (Camerlink et al.,
2012). Im Folgenden werden die verschiedenen Formen der Verhaltensstörung, die
gesetzlichen Grundlagen für das Kupieren, Risikofaktoren für Schwanzbeißen sowie
mögliche Indikatoren eines bevorstehenden Ausbruches dargestellt.
Formen des Schwanzbeißens
In der Literatur sind verschiedene Formen von Schwanzbeißen beschrieben. Taylor et al.
(2010) differenzieren ein „zweistufiges Beißen“ von plötzlich auftretendem „gewaltsamen
Beißen“ und „obsessivem Beißen“. Die Unterschiede zwischen diesen drei Formen der
Verhaltensstörung liegen zum einen in der Art und Weise der Ausübung des Verhaltens und
zum anderen in den Ursachen, die diesem Verhalten zugrunde liegen.
„Zweistufiges Beißen“: Diese Form des Schwanzbeißens beginnt spielerisch mit einem
sogenannten „tail-in-mouth behaviour“ (Schrøder-Petersen et al., 2003), welches als
10
physiologisches Erkundungsverhalten der Tiere gewertet wird. Während dieses Stadiums hat
ein Schwein den Schwanz eines anderen im Maul und manipuliert ihn, ohne sichtbaren
Schaden anzurichten (Taylor, et al., 2010). Im Falle unzureichender
Beschäftigungsmöglichkeiten kann der unbefriedigte Erkundungs- und Wühltrieb zu
vermehrten/ verstärkten Manipulationen am Schwanz und dabei zu Verletzungen der Haut
führen (Schrøder-Petersen, et al., 2003). Ist diese Stufe erreicht, steigert das austretende Blut
und Wundsekret die Attraktivität der verletzten Schwänze für die Buchtengenossen, die
dadurch animiert, vermehrt Schwanzbeißen zeigen können. Eine wichtige Maßnahme zur
Reduktion ist eine intensive Tierbeobachtung und eine sofortige Bereitstellung von
zusätzlichem Beschäftigungsmaterial zur Ablenkung der Tiere (Veit et al., 2014).
„Plötzliches und gewaltsames Beißen“: Diese Form des Schwanzbeißens zeichnet sich durch
vereinzelt auftretende massive Beißaktionen aus, die vor allem auf einen Mangel an
Ressourcen zurückzuführen ist. Ein unzureichendes Tier-Fressplatzverhältnis kann
beispielsweise ein benachteiligtes Tier dazu verleiten, den Konkurrenten mittels auf den
Schwanz gerichteter Beißattacken vom Futtertrog zu vertreiben. Auch mangelnder
Liegekomfort ist möglicherweise eine der Ursachen für Frustration und daraus resultierendes
Schwanzbeißen (Widowski, 2002). Weitere Umweltstressoren wie zum Beispiel Mängel in
der Lüftungs- (Hitze-/ Kältestress) oder Fütterungstechnik können diese Form der
Verhaltensstörung provozieren. Mögliche Maßnahmen sind vor allem das Beheben der
jeweiligen Mängel.
„Obsessives Beißen“: Bei dieser Form des Schwanzbeißens handelt es sich um ein eher
seltener beobachtetes Fehlverhalten von einzelnen Individuen, welches als pathologischer
Wandel hin zu Stereotypien gewertet werden kann (Taylor et al., 2010). In diesem Fall richten
Einzeltiere Beißattacken gegen die Schwänze von Buchtengenossen und entfernen innerhalb
sehr kurzer Zeit die Hautschichten bis hin zur Amputation von Teilen oder des gesamten
Schwanzes. Über die Ursachen für diese Form der Verhaltensstörung ist wenig bekannt;
möglicherweise hat der individuelle Gesundheitsstatus des jeweiligen Tieres eine besondere
Bedeutung. Die sicherste Maßnahme zur Behebung dieses Fehlverhaltens ist eine Isolierung
des Täters, die auch dringend erforderlich ist, um die Gruppe vor weiteren Verletzungen zu
schützen (Taylor et al., 2010).
11
Gesetzliche Grundlagen für das Schwanzkupieren bei Schweinen
Die EU Gesetzgebung (Richtlinie 2001/ 93/ EG, Anhang, Kapitel 1, Artikel 8) legt Folgendes
fest: „Ein Kupieren der Schwänze oder eine Verkleinerung der Eckzähne dürfen nicht
routinemäßig und nur dann durchgeführt werden, wenn nachgewiesen werden kann, dass
Verletzungen am Gesäuge der Sauen oder an den Ohren oder Schwänzen anderer Schweine
entstanden sind. Bevor solche Eingriffe vorgenommen werden, sind andere Maßnahmen zu
treffen, um Schwanzbeißen und andere Verhaltensstörungen zu vermeiden, wobei die
Unterbringung und Belegungsdichte zu berücksichtigen sind.“ Zu den europäischen Ländern,
in denen das Kupierverbot grundsätzlich strikt umgesetzt wird, zählen Finnland, Litauen
Norwegen, Schweden und die Schweiz. In diesen Ländern ist Kupieren nur in
Ausnahmefällen und nur mit einer Anästhesie erlaubt. Das deutsche Tierschutzgesetz
verbietet „[...] das vollständige oder teilweise Amputieren von Körperteilen […] eines
Wirbeltieres“ zwar auch, das Verbot gilt aber nicht, wenn der „Eingriff im Einzelfall nach
tierärztlicher Indikation geboten ist […]“ (TierSchG 2006, § 6, Absatz 1). Diese gesetzliche
Ausnahme wird in Deutschland zurzeit als Grundlage genutzt, um ein flächendeckendes
routinemäßiges Kürzen der Schwänze in der Praxis durchzuführen. Die Bundesländer
Nordrhein-Westfalen, Niedersachsen und Schleswig-Holstein haben spezielle Vereinbarungen
geschlossen, das routinemäßige Kupieren bis 2016/ 2017 zu unterbinden. Das Ministerium in
Niedersachsen hat in diesem Rahmen mit Hilfe des Europäischen Landwirtschaftsfonds für
die Entwicklung des ländlichen Raumes (ELER) die sogenannte „Ringelschwanzprämie“
eingeführt, um einen finanziellen Anreiz für die Umsetzung des Kupier-Verbotes zu setzen.
Die „Gemeinsamen Eckpunkte zur Tierwohlförderung“ sind neben dem Niedersächsischen
Landwirtschaftsministerium von der Interessengemeinschaft der Schweinehalter Deutschlands
(ISN) sowie vom Agrar- und Ernährungsforum Oldenburger Münsterland (AEF)
unterzeichnet worden (NMELV, 2015).
Effekt des Schwanzkupierens beim Schwein
Das Kupieren der Schwänze ist eine weitverbreitete präventive Maßnahme, die bei
Schwanzbeißen im Schweinebestand angewendet wird (Bracke et al., 2012). Als einer der
Gründe für den „Erfolg“ des Schwanzkupierens wird u. a. eine Hyperalgesie des
Amputationsstumpfes vermutet, die dazu führt, dass Schweine schneller abwehrend auf
12
Manipulationen am Schwanz reagieren (Simonsen et al., 1991). Die Wahrscheinlichkeit,
Opfer einer Beißattacke zu sein, stieg in einer Studie, die an 63 000 Schweinen auf sechs
Schlachthöfen in Großbritannien durchgeführt wurde, um den Faktor 2,73 an, wenn die
Schwänze nicht kupiert waren (Hunter et al., 1999). Di Martino et al. (2015) untersuchten den
Effekt des Kupierens auf das Tierwohl von Schweinen (4.-40. Lebenswoche), die nicht unter
optimalen Bedingungen gehalten wurden (Besatzdichte 0,32 m²/ Tier in der Ferkelaufzucht,
Vollspaltenboden, Probleme mit PRRS, Influenza und Actinobacillus pleuropneumoniae im
Bestand). Die nicht kupierten Tiere wiesen unter diesen Bedingungen zwar vermehrt
Schwanzverletzungen auf, das Tierwohl, welches anhand von Blutparametern,
Verhaltensbeobachtungen und Mortalitätsraten beurteilt wurde, war jedoch nicht generell
schlechter als in einer kupierten Kontrollgruppe. Darüber hinaus ist festzustellen, dass
Kupieren das Problem des Schwanzbeißens weder vollständig verhindern kann, noch die
eigentlichen Ursachen behebt (Nannoni et al., 2014). Gerade im Hinblick auf die aktuelle
Verbraucherdiskussion zum Thema Tierwohl in der Nutztierhaltung gehen die Bestrebungen
dahin, die Integrität des Tierkörpers zu erhalten und die Haltungsbedingungen für die Tiere
soweit zu optimieren, dass eine Haltung von Schweinen mit intakten Schwänzen unter
Praxisbedingungen möglich wird.
Mechanismen und Ursachen von Schwanzbeißen
Grundsätzlich verfügen Tiere über unterschiedliche und individuell ausgeprägte
Bewältigungsstrategien („Coping-Strategien“), um auf Anforderungen, z. B. aus ihrer
Haltungsumgebung zu reagieren. Bolhuis et al. (2005) untersuchten die individuellen
Anpassungsstrategien von Schweinen mit Hilfe eines sogenannten „Back-Tests“. Für den
„Back-Test“ werden die Tiere in einer speziellen Vorrichtung auf den Rücken gelegt und die
Anzahl der Fluchtversuche innerhalb einer Minute dokumentiert. Ein Schwein wurde als
„stark reagierend“ klassifiziert, wenn es mehr als vier Fluchtversuche in zwei Tests zeigte und
als „schwach reagierend“, wenn die Anzahl der Fluchtversuche in zwei Tests unter vier lag.
Die als „stark reagierend“ klassifizierten Tiere zeigten vermehrt aggressives Verhalten
(Kopfschläge, Beißen und Kämpfe) gegenüber Buchtengenossen, während die als “schwach
reagierend” klassifizierten Tiere vermehrt manipulatives Verhalten („belly nosing“, Ohren-
oder Schwanzbeißen) zeigten. Diese tierindividuellen Unterschiede sind ein möglicher
13
Ansatzpunkt, warum Schwanzbeißen unregelmäßig und scheinbar keinem Muster folgend in
den Beständen auftritt. Dabei wird häufig geschildert, dass nur einzelne Buchten betroffen
sind und die Ursachen des jeweiligen Ausbruches schwer nachzuvollziehen sind.
Darüber hinaus besteht die Problematik vor allem in den multifaktoriellen Ursachen des
Geschehens. Jeder Stressor, sei er beispielsweise klimatischer, diätetischer oder
gruppendynamischer Ursache, kann die Tiere und deren physiologische Verhaltensmuster aus
dem Gleichgewicht bringen. Jeder Einflussfaktor hat einen additiven Effekt auf das
Gesamtrisiko und die zuletzt hinzugekommen Stressoren können das sprichwörtliche „Fass
zum Überlaufen“ bringen. Der Risikofaktor, der dann als Auslöser für Schwanzbeißen im
Bestand gilt, muss – dem Modell folgend – dabei nicht unbedingt der mit dem höchsten
Einzelrisiko sein (EUWelNet, 2013). Im Folgenden werden die möglichen und häufig
diskutierten Ursachen des Schwanzbeißens erläutert und der Fokus besonders auf die
Faktoren Beschäftigungsmaterial und Absetzmanagement gelegt.
Anreicherung der Haltungsumgebung
Durch das europäische Recht (Richtlinie 2008/ 120/ EG, Anhang 1, Kapitel 1, allgemeine
Bedingungen § 4) ist festgelegt, dass Schweine ständigen Zugang zu ausreichenden Mengen
an Materialien haben müssen, die sie untersuchen und bewegen können, wie z. B. Stroh, Heu,
Holz, Sägemehl, Pilzkompost, Torf […]. Der Mangel an wühlbarem Substrat wurde bereits
als ein ausschlaggebendes Risiko für Schwanzbeißen identifiziert und die Motivation,
Erkundungsverhalten auszuüben, wird als eine der Hauptfaktoren für Schwanzbeißen
angesehen (EFSA, 2007). Dabei ist zu beachten, dass Schweine unter seminatürlichen
Bedingungen 75 % der Tagesaktivität mit Erkundungsverhalten und Futtersuche verbringen
(Stolba und Wood-Gush, 1989). Diese Verhaltensweisen können in der reizarmen Umgebung
von intensiven Haltungssystemen nur zu einem geringen Anteil ausgeübt werden. Wenn kein
passendes Beschäftigungsmaterial verfügbar ist, können Schweine ihr Suchverhalten auf
Buchtengenossen oder auf die Buchtenumgebung ausweiten (EFSA, 2007). Schweine in einer
reizarmen Haltung (untersucht in der 4., 7. und 18. Lebenswoche) manipulierten nachweislich
häufiger den Boden, die Wände und Buchtengenossen und zeigten häufiger Schwanzbeißen
als Schweine in einer angereicherten Haltung (Petersen et al., 1995). Das Angebot von
Pilzkompost bei konventionell gehaltenen Mastschweinen reduzierte z. B. die Umorientierung
14
von Wühlverhalten auf Buchtengenossen und verbesserte das Tierwohl zusätzlich aufgrund
des seltener vorkommenden Schwanzbeißens (Sneddon et al., 2001). Van de Weerd et al.
(2003) untersuchten 74 verschiedene Objekte zur Umweltanreicherung und betonten die
Bedeutung der Materialeigenschaften „kaubar“, „verformbar“ und „zerstörbar“. Demzufolge
ist die Manipulierbarkeit des Beschäftigungsmaterials für Schweine ein wichtiger Aspekt.
Dieses sollte dem Anspruch an ihr natürliches Futtersuchverhalten entsprechen, welches die
Erkundung der Umgebung mittels Wühlen, Schnüffeln, Beißen und Kauen umfasst (Studnitz
et al., 2007). Außerdem verringert eine Anreicherung der Umwelt die Zeit, in der die Tiere in
negatives Sozialverhalten und aggressive Verhaltensweisen involviert sind (Beattie et al.,
2000). Van de Weerd et al. (2006) verglichen verschiedene Maßnahmen zur Beschäftigung:
Strohautomat, Futterautomat, Tränkeautomat, mit Stroh eingestreuter Liegebereich und ein
kommerzielles Beschäftigungsobjekt („Bite Rite“). Der eingestreute Liegebereich war die
erfolgreichste Maßnahme, die Schweine zu beschäftigen und schweres Schwanzbeißen zu
verhindern, wohingegen in Gruppen, die nur mit zusätzlichen Tränkeautomaten und Bite Rite
ausgestattet waren, die höchste Prävalenz an Schwanzbeißen festzustellen war. Scott et al.
(2007) verglichen die Aktivitätslevel von Schweinen in unterschiedlich ausgestatteten
Buchten und stellten fest, dass sie sich deutlich länger mit Stroh als mit Plastikrohren
beschäftigten. Die Bereitstellung von Stroh reduzierte, ungeachtet der Faserlänge, das
Auftreten von Verhaltensweisen wie „nosing“ (Manipulation von Buchtengenossen über die
Schnauze), Aggression und Schwanzbeißen im Vergleich zu strohloser Haltung. Die
Prävalenz von Schwanzbeißen in Gruppen mit kurzfaserigem Stroh war jedoch höher als in
den Gruppen, denen langes oder nur teilweise gekürztes Stroh angeboten wurde (Day et al.,
2008). Amdi et al. (2015) untersuchten den Einfluss von Stroh, das in unterschiedlichen
Mengen (25 g/ 50 g/ 100 g/ Schwein/ Tag) und Häufigkeiten (1 x/ 2 x/ 4 x täglich) angeboten
wurde, auf das Auftreten von negativen, gegen Buchtengenossen gerichteten
Verhaltensweisen. Ein Unterschied zwischen diesen Versuchsgruppen konnte nicht
festgestellt werden. Zonderland et al. (2008) testeten vier verschiedene
Präventionsmaßnahmen (Kette, Reifen, Strohgabe über eine Raufe und auf den Boden) und
stellten fest, dass Schwanzbeißen am effektivsten mit einer kleinen Menge Stroh, das zweimal
täglich auf den Boden verabreicht wurde, zu verhindern war, während Strohraufe, Kette oder
Reifen einen geringeren und in dieser Reihenfolge abnehmenden präventiven Effekt hatten.
15
Eine auf zweimal pro Woche reduzierte Strohgabe konnte die Anzahl von
Schwanzbeißaktionen nicht signifikant reduzieren (Statham et al., 2011). Nach Day et al.
(2002) steigert das Umstallen von Schweinen aus einer eingestreuten in eine nicht
eingestreute Haltungsumgebung manipulative Verhaltensweisen gegen Buchtengenossen.
Diese Erkenntnis trägt zu der Annahme bei, dass Schweine, die an Beschäftigungsmaterial
gewöhnt sind, möglicherweise frustriert werden, wenn das Material nicht mehr zur Verfügung
steht. Munsterhjelm et al. (2009) verglichen Gruppen, die in früheren Lebensabschnitten
(Abferkelbereich und Aufzucht) Beschäftigungsmöglichkeiten zur Verfügung hatten, mit
Gruppen, die erst in späteren Lebensabschnitten zusätzliche Beschäftigung erfahren hatten.
Ein Mangel an Beschäftigung während der Mast führte zu erhöhten Schwanzverletzungen in
Gruppen, die bereits in den ersten Lebensphasen Beschäftigungsmaterial erhalten hatten. Eine
Anreicherung der Umwelt vor dem Absetzen kann somit Auswirkungen auf das
Schwanzbeißverhalten in späteren Lebensabschnitten haben (Oostindjer et al., 2010).
Saugferkel, die in konventionellen Abferkel-Systemen von der Geburt bis zum Absetzen
Zugang zu Seilen und Zeitungen hatten, übten weniger oro-nasale Manipulationen an
anderen Ferkeln aus, als die Ferkel der Kontrollgruppe, die ohne Beschäftigungsmaterial
gehalten wurden. Entsprechend hatten die Schweine aus der Gruppe mit
Beschäftigungsmaterial während der Säugezeit nach dem Absetzen weniger häufig schwere
Schwanzverletzungen als Schweine der Kontrollgruppe (Telkänranta et al., 2014). Die
genannten Studien zeigen, dass Beschäftigungsmaterial eine wichtige Rolle in der Prävention
von Verletzungen durch Schwanzbeißen spielt, da es den Tieren ermöglicht, eine größere
Bandbreite ihres Verhaltensrepertoires auszuleben. Allerdings muss beachtet werden, dass
diese Beschäftigungsmaterialien zumeist nicht zu den weitverbreiteten Vollspaltenböden und
den heutigen Güllesystemen in der konventionellen Schweinehaltung passen. Die
Verwendung von gekürztem Material, welches das Risiko verstopfter Leitungssysteme
minimiert, könnte ein möglicher Kompromiss sein.
Absetzmanagement
Eine weitere Besonderheit des Themas Schwanzbeißen ist der zeitliche Zusammenhang
zwischen dem Auftreten der Verhaltensstörung und dem Absetzen. In der zweiten Woche
nach dem Umstallen in die Ferkelaufzucht wurden bereits erste Schwanzverletzungen
16
beobachtet (Abriel and Jais, 2013; Veit et al., 2014). Schweine sind in den heutigen intensiven
Haltungsformen mit vielen Herausforderungen konfrontiert. Der wohl massivste Einschnitt in
das Leben eines Ferkels ist dabei das Absetzen, das mit der Trennung von der Muttersau, und
üblicherweise auch mit einer Änderung der Haltungsumgebung (sozial und räumlich), teils
sogar mit einem Transport einhergeht. Möglicherweise sind die Ferkel in den ersten Tagen
nach dem Absetzen mit dem Kennenlernen der neuen Umgebung und der Festlegung der
Rangordnung mit den Buchtengenossen beschäftigt. Fehlen anschließend
Beschäftigungsmöglichkeiten, kann die reizarme Umgebung zu Frustration bei den Tieren
führen und Schwanzbeißen auslösen, was wiederum den zeitlichen Bezug zum Absetzen
erklären könnte. Zusätzlich zu den damit verbundenen Stressoren findet bei dem Übergang
vom Abferkelbereich in die Ferkelaufzucht häufig auch eine mehr oder weniger abrupte
Futterumstellung statt, mit der die Ferkel konfrontiert sind. Unter natürlichen Bedingungen
erfolgt die Entwöhnung von der Muttermilch schrittweise über einen längeren Zeitraum, der
bis zu einem Alter von zehn bis zwölf Wochen noch nicht abgeschlossen ist (Lallès et al.,
2007). Außerdem entspricht das routinemäßig angewandte Sortieren der Würfe beim
Absetzen nach Größe und eventuell auch nach Geschlecht, nicht den natürlichen
Gegebenheiten in einer Rotte und erfordert von den Läufern das Festlegen einer neuen
Rangordnung mit wurffremden Artgenossen. Beim Mischen von zwei Würfen, zeigten die
Tiere ein gesteigertes agonistisches Verhalten und Erkundungsverhalten, hatten kürzere
Ruhephasen und wiesen einen höheren Anteil von schweren Hautläsionen auf (Hötzel et al.,
2011). Frühes Mischen von unbekannten Würfen während der Laktation reduzierte dagegen
agonistische Verhaltensweisen und Läsionen in den ersten zwei Tagen nach dem Absetzen
(Bohnenkamp et al., 2012). Stress durch das Mischen der Tiere gilt somit als möglicher
Auslöser für Schwanzbeißen unter konventionellen Bedingungen (EFSA, 2007). Von
Bedeutung scheint zudem auch die Haltung der Tiere vor dem Absetzen zu sein. Die
Sozialisierung von Ferkeln aus verschiedenen Würfen hatte Langzeiteffekte auf das
Sozialverhalten der Tiere, reduzierte sozialen Stress zum Absetzen und erhöhte den Zuwachs
in der nachfolgenden Aufzucht (D‘Eath et al., 2005; Kutzer et al., 2009). Schweine, die in
einem Gruppen-Abferkelungs-System aufwuchsen, waren weniger aggressiv und toleranter
gegenüber unbekannten Buchtengenossen als Schweine aus konventionellen
17
Abferkelungssystemen, in denen sich die Ferkel erst nach dem Absetzen erstmalig begegneten
(Li and Wang, 2011).
Einfluss weiterer Faktoren
Ein weiterer Faktor, der das Auftreten der Verhaltensstörung „Schwanzbeißen“ beeinflusst, ist
die Genetik. Breuer et al. (2003) untersuchten jeweils 100 Schweine von drei verschiedenen
Rassen (Large White, Landrasse und Duroc) individuell in einem „tail chew test“. Dazu
wurden den Tieren jeweils zwei Seile angeboten und die Dauer und Häufigkeit des Seil-
gerichteten Verhaltens über einen Zeitraum von zehn Minuten dokumentiert. Außerdem
wurde das Auftreten von negativem Sozialverhalten gegenüber Buchtengenossen nach dem
Absetzen in der Ferkelaufzucht erfasst. Die Rasse hatte einen signifikanten Effekt sowohl auf
die Intensität des Seil-gerichteten Verhaltens im „tail chew test“ als auch auf negatives
Sozialverhalten. Tiere der Rasse Duroc interagierten häufiger und länger mit dem
angebotenen Seil und zeigten auch häufiger gegen Buchtengenossen gerichtetes
Beißverhalten. In einer nachfolgenden Studie wurden klinische Beißer (295 aus 9018 Ferkel)
identifiziert und ihrer Abstammung zugeordnet (Breuer et al., 2005). Die Inzidenz für
Schwanzbeißen war dabei für Schweine der Rasse Large White geringer als für Landrasse.
Schwanzbeißen konnte für die Landrasse-Tiere als erblich festgestellt werden (h² = 0,27). In
anderen Untersuchungen wurde nachgewiesen, dass Schweine der Rasse Yorkshire häufiger
Opfer von Schwanzbeißen waren als Schweine der Landrasse. Die Häufigkeit des
Schwanzbeißens stieg mit zunehmendem Magerfleischanteil und abnehmender
Rückenspeckdicke an (Moinard et al., 2003; Sinisalo et al., 2012). Bei der Bewertung des
Effektes des Magerfleischanteils ist zu bedenken, dass aufgrund von Verbraucherinteressen in
den letzten Jahrzehnten in der Zucht verstärkt auf einen immer höheren Magerfleischanteil
selektiert wurde.
Ein weiterer Aspekt, der im Zusammenhang mit der Verhaltensstörung Schwanzbeißen
diskutiert werden sollte, ist das Geschlecht. In Untersuchungen an Schlachthöfen (Hunter et
al., 1999; Kritas and Morrison, 2007; Keeling et al., 2012) wurde festgestellt, dass männliche
Schweine eher Bissverletzungen aufwiesen als weibliche Schweine. Darüber hinaus wurden
Kastraten eher gebissen als Eber (Walker and Bilkei, 2006). Im Gegensatz dazu konnten
18
Sinisalo et al. (2012) keine signifikanten Unterschiede zwischen Ebern, weiblichen Tieren
und Kastraten im Risiko, Opfer von Schwanzbeißen zu werden, beobachten.
Neben dem Geschlecht hat auch die Gruppenzusammensetzung eine Bedeutung für das
Auftreten von Schwanzbeißen. Nach Schrøder-Petersen et al. (2004) ist die Häufigkeit von
„tail-in-mouth behaviour“ signifikant niedriger in rein männlichen Gruppen als in weiblichen
oder gemischt-geschlechtlichen Gruppen. In vergleichenden Untersuchungen konnte
festgestellt werden, dass weibliche Ferkel eher zu Schwanzbeißen neigen als männliche
(Zonderland et al., 2010). Außerdem wurden bei Tieren, die in gemischt-geschlechtlichen
Gruppen gehalten wurden, weniger häufig Schwanzverletzungen am Schlachthof registriert,
als in getrennt-geschlechtlichen Gruppen (Hunter et al., 2001). „Tail-in-mouth behaviour“ trat
hingegen in getrennt-geschlechtlichen Gruppen signifikant weniger häufig auf, als in
gemischt-geschlechtlichen (Schrøder-Petersen, et al., 2003). Im Gegensatz dazu konnten
Moinard et al. (2003) keinen Zusammenhang zwischen der Geschlechterverteilung und dem
Auftreten von Schwanzbeißen beobachten.
Neben den genannten biologischen Risikofaktoren gibt es auch einige Managementfaktoren,
die entscheidenden Einfluss auf das Schwanzbeißen haben können. Eine Belegdichte von
110 kg/ m² oder mehr während der Ferkelaufzucht und Mast erhöhte das Risiko für
Schwanzbeißen um den Faktor 2,7 (Moinard, et al., 2003). Andererseits haben Beattie et al.
(1996) eine Besatzdichte von 0,5, 1,1, 1,7 und 2,3 m² pro Schwein vergleichend untersucht
und vermuten, dass weniger die Größe der verfügbaren Fläche das Verhalten der Schweine
beeinflusst als die Ausgestaltung der Buchten. Nach Abriel und Jais (2013) waren die
Unterschiede in der Häufigkeit von Schwanzverletzungen zwischen angereicherten Buchten
mit normaler und reduzierter Besatzdichte gering. Rodenburg und Koene (2007) haben den
Einfluss der Gruppengröße auf negatives Sozialverhalten, Aggression, Angst und Stress bei
landwirtschaftlichen Nutztieren untersucht. Sie schlussfolgerten, dass es für eine Reduktion
der oben genannten Verhaltensweisen wichtig ist, eine komplexe Umgebung und separate
Funktionsräume zum Ausleben vielfältiger Verhaltensweisen zur Verfügung zu stellen. Nach
Schmolke et al. (2003) haben unterschiedliche Gruppengrößen (10, 20, 40 und 80 Tiere im
Vergleich) keinen Effekt auf das Auftreten von Schwanzbeißen.
19
In Bezug auf das Klima und die Lüftung sind die Ergebnisse eindeutiger. Seit Längerem ist
bekannt, dass erhöhte Ammoniakgehalte bei den Tieren Stress hervorrufen. Besonders in den
kritischen Wochen nach dem Absetzen wurden Aggressionen vermehrt bei Schweinen
beobachtet, die bei 20 vs. < 5 ppm Ammoniak und 40 vs. 200 Lux Lichteinstrahlung gehalten
wurden (Parker et al., 2010). Der Ammoniakgehalt der Versuchsgruppe erreicht hierbei die
gesetzlich festgelegte Obergrenze, während die Lichteinstrahlung die gesetzlich
vorgeschriebenen Bedingungen um die Hälfte unterschreitet (TierSchNutztV, 2006, Abschnitt
5, § 26). Daraus ist allerdings nicht abzuleiten, dass ein Gehalt von 20 ppm Ammoniak
toleriert wird und allein die unzureichende Lichtstärke die Aggressionen induziert hat. Mit
Hilfe des „husbandry advisory tools“ wurde vielmehr herausgestellt, dass die Kategorie Klima
und Umgebung (Temperatur, Feuchtigkeit, Züge, aversive Faktoren in der Atmosphäre z. B.
Ammoniak/ Staub im Liegebereich) den wichtigsten Risikofaktor für Schwanzbeißen bei
Mastschweinen in konventionellen Betrieben darstellt (Taylor et al., 2012).
Ein weiteres Thema, das in Bezug auf Schwanzbeißen Erwähnung finden muss, ist die
Fütterung. Wie bereits angesprochen, ist ein ausreichendes Tier-Fressplatzverhältnis
entscheidend für eine stressfreie Nahrungsaufnahme, die allen Tieren zur gleichen Zeit
ermöglicht werden sollte (Hansen et al., 1982). Die Nutzung eines Fütterungssystems mit fünf
oder mehr Schweinen pro Fressplatz erhöhte das Risiko für Schwanzbeißen (Moinard et al.,
2003). Schweine können über das Erkundungsverhalten ernährungsphysiologische
Information gewinnen und über diesen Ernährungs-Feedback das Futteraufnahmeverhalten
dahingehend verändern, dass diätetische Defizite korrigiert werden (Jensen et al. 1993; Day et
al., 1996). Beattie et al. (2005) vermuteten weitergehend, dass Schweine, die Schwanzbeißen
zeigen, ernährungsphysiologische Defizite aufweisen, was zu einem intensiveren
Erkundungsverhalten in Form von fortgesetztem „Bekauen“ der Buchtgenossen führt. Anhand
histologischer Untersuchungen des Darms von Tieren in einer Bucht, in der Schwanzbeißen
auftrat, konnten verkürzte Dünndarmzotten und darüber hinaus geringere
Plasmakonzentrationen an Aminosäuren bei den Opfern von Schwanzbeißen nachgewiesen
werden (Palander et al., 2013). Mögliche Erklärungen hierfür sind eine verringerte
Absorptionskapazität, ein geändertes Fressverhalten oder eben Umweltstress infolge
Schwanzbeißens. Einen weiteren Einfluss auf das Auftreten von Schwanzbeißen hat die
Zusammensetzung der Ration. Hohe Rohfasergehalte in der Ration reduzieren fehlgeleitetes
20
Erkundungsverhalten (Brouns et al., 1994), eine mögliche Erklärung hierfür ist ein länger
anhaltendes Sättigungsgefühl. Außerdem wurde vermehrt Schwanzbeißen beobachtet, wenn
Schweine eine proteinarme Ration im Gegensatz zu einer adäquaten Proteinversorgung
erhalten (BPEX, 2005). Ein Faktor, der weitergehend untersucht werden sollte, ist das
zeitliche Fütterungsregime. Schweine, die ad libitum gefüttert wurden, erkundeten angebotene
Beschäftigungsmaterialien weniger häufig als restriktiv gefütterte Tiere (Zwicker et al., 2013).
Neben der Fütterung ist ein guter Gesundheitszustand zur Vermeidung von Schwanzbeißen
von entscheidender Bedeutung (Moinard et al., 2003; Walker and Bilkei, 2006). Das
Auftreten von respiratorischen Erkrankungen ist mit einer 1,6 fachen Steigerung des Risikos
für Schwanzbeißen assoziiert (Moinard, et al., 2003). Schweine, die erkrankt sind, sind
zurückhaltender in der Abwehr von Beißern und unfähig, sich zu verteidigen (Kritas and
Morrison, 2004). Außerdem haben erkrankte Tiere geringere Wachstumsraten, was
abnehmende Chancen reflektiert, sich im Kampf um Ressourcen gegen Buchtengenossen
durchzusetzen, was wiederum Schwanzbeißen auslösen kann (Taylor, et al., 2010).
Indikatoren
Videobeobachtungen auf Einzeltierbasis liefern Erkenntnisse zum individuellen Verhalten der
Schweine. Nach Zonderland et al. (2010) steigen, unabhängig vom Schweinetyp, Unruhe und
die Häufigkeit der Beißaktivitäten in den Tagen vor einem Schwanzbeißausbruch an. Als
Ausbruch wurde dabei der Tag definiert, an dem mindestens ein Ferkel eine tiefergehende
Wunde am Schwanz aufwies, beziehungsweise bei mindestens zwei Ferkeln oberflächliche
Kratzwunden an den Schwänzen beobachtet wurden. Die Erfassung der Inzidenz des „tail-in-
mouth behaviour“ lieferte bereits sechs Tage bevor die ersten Schwanzverletzungen in einer
Bucht auftraten Hinweise auf Tiere, die später zu ausgeprägten Beißern wurden (Zonderland
et al., 2011).
Die Messung des Aktivitätsverhaltens ist ein vielversprechendes Instrument, um den
Ausbruch von Schwanzbeißen vorherzusagen (Statham et al., 2009). Die retrospektive
Auswertung des Aktivitätsniveaus war in Gruppen, in denen vier Tage später ein Ausbruch
stattgefunden hat, signifikant höher, als in den Kontrollgruppen. In Übereinstimmung damit
wurde eine höhere Aktivität und ein gesteigertes manipulatives Verhalten gegenüber
21
Buchtengenossen und -umgebung dort beobachtet, wo Schwanzbeißen auftrat (Ursinus et al.,
2014). Außerdem konnte Schwanzbeißen mit anderen manipulativen Verhaltensweisen, wie
zum Beispiel Ohrenbeißen und „nosing“ in der Genital- und Bauchregion, in Verbindung
gesetzt werden (Beattie, et al., 2005).
Neben dem Aktivitätsverhalten ist auch die Schwanzhaltung der Tiere ein interessanter
Indikator. Als Zeichen der Domestikation besitzen die heutigen Schweinerassen einen
Ringelschwanz; dieser dient der Kommunikation und drückt möglicherweise den mentalen
Zustand der Tiere aus (Groffen, 2012). McGlone et al. (1990) beobachteten in ihrer Studie,
dass Schweine bei wiederholten Schwanzbeißausbrüchen ihre Schwanzhaltung änderten. Die
Autoren sehen diese Veränderung als Angstreaktion und vermuten, dass ein Einklemmen des
Schwanzes möglicherweise Schutz vor Beißern bietet. In Übereinstimmung damit wurde
beobachtet, dass in Gruppen ohne Schwanzbeißausbruch weniger Schweine ihre Schwänze
„zwischen die Beine geklemmt“ hatten (Statham, et al., 2009). Zonderland et al. (2009)
schlussfolgerten, dass die Schwanzhaltung der Schweine mit Manipulationen am Schwanz
zusammenhängt, und dass auffällige Verletzungen anhand der Schwanzhaltung zwei bis drei
Tage im Voraus vorhergesagt werden können.
Schlussfolgerungen
Die Schwierigkeit im Umgang mit dem Thema Schwanzbeißen liegt vor allem in den
multifaktoriellen Ursachen des Geschehens. Eine sichere Vermeidung der Verhaltensstörung
bei der Aufzucht unkupierter Tiere in der intensiven Nutztierhaltung ist durch einen einzelnen
Lösungsansatz nicht möglich. Vielmehr braucht jeder Betrieb eine eigene Strategie und vor
allem Erfahrungswerte in der Bekämpfung der Verhaltensstörung, da jedes System
unterschiedliche Einflussfaktoren hat, auf die individuell reagiert werden muss. Dabei stehen
neben optimalem Management und einer guten Tiergesundheit vor allem eine intensive
Tierbeobachtung und sofortige Intervention beim Auftreten von Schwanzbeißen im
Vordergrund (Veit, et al., 2014). Die Verhaltensstörung Schwanzbeißen drückt eine
Überforderung der Anpassungsfähigkeit der Tiere in intensiven Haltungsbedingungen aus.
Diese müssen dahingehend verändert werden, dass den Schweinen ein Ausleben der
angeborenen Verhaltensweisen ermöglicht wird. Eine wichtige Maßnahme zur Befriedigung
des Wühl- und Erkundungsverhaltens ist das Angebot von organischem
22
Beschäftigungsmaterial. Außerdem sollten weitergehende Untersuchungen den Fokus vom
Opfertier auf das Tätertier lenken und tierindividuelle Defizite analysieren, um der
Verhaltensstörung auf den Grund zu gehen.
Quellen
2001/ 93/ EG. Richtlinie 2001/ 93/ EG der Kommission vom 9. November 2001 zur
Änderung der Richtlinie 91/ 630/ EWG über Mindestanforderungen für den Schutz
von Schweinen.
2008/ 120/ EG. Richtlinie des Rates 2008/ 120/ EG vom 18. Dezember 2008 über
Mindestanforderungen für den Schutz von Schweinen.
Abriel, M., and C. Jais. 2013. Influence of housing conditions on the appearance of
cannibalism in weaning piglets. Landtechnik 68: 389-393.
Amdi, C. et al. 2015. Pen-mate directed behaviour in ad libitum fed pigs given different
quantities and frequencies of straw. Livestock Science 171: 44-51.
Beattie, V. E. et al. 2005. Factors identifying pigs predisposed to tail biting. Animal Science
80: 307-312.
Beattie, V. E., N. E. O'Connell, and B. W. Moss. 2000. Influence of environmental
enrichment on the behaviour, performance and meat quality of domestic pigs.
Livestock Production Science 65: 71-79.
Beattie, V. E., N. Walker, and I. A. Sneddon. 1996. An investigation of the effect of
environmental enrichment and space allowance on the behaviour and production of
growing pigs. Applied Animal Behaviour Science 48: 151-158.
Bohnenkamp, A. L., I. Traulsen, C. Meyer, K. Müller, and J. Krieter. 2012. Comparison of
growth performance and agonistic interaction in weaned piglets of different weight
classes from farrowing systems with group or single housing. Animal 7: 309-315.
Bolhuis, J. E., W. G. P. Schouten, J. W. Schrama, and V. M. Wiegant. 2005. Behavioural
development of pigs with different coping characteristics in barren and substrate-
enriched housing conditions. Applied Animal Behaviour Science 93: 213-228.
BPEX. 2005. Finishing pigs systems research production trial 4. British Pig Executive, Milton
Keynes.
23
Bracke, M. B. M., C. De Lauwere, S. M. Wind, and J. Zonerland. 2012. Attitudes of dutch pig
farmers towards tail biting and tail docking. Journal of Agricultural and
Environmental Ethics 26: 847-868.
Breuer, K. et al. 2003. The effect of breed on the development of adverse social behaviours in
pigs. Applied Animal Behaviour Science 84: 59-74.
Breuer, K. et al. 2005. Heritability of clinical tail-biting and its relation to performance traits.
Livestock Production Science 93: 87-94.
Brouns, F., S. A. Edwards, and P. R. English. 1994. Effect of dietary fibre and feeding system
on activity and oral behaviour of group housed gilts. Applied Animal Behaviour
Science 39: 215-223.
Camerlink, I., P. Bijma, B. Kemp, and J. E. Bolhuis. 2012. Relationship between growth rate
and oral manipulation, social nosing, and aggression in finishing pigs. Applied Animal
Behaviour Science 142: 11-17.
D'Eath, R. B. 2005. Socialising piglets before weaning improves social hierarchy formation
when pigs are mixed post-weaning. Applied Animal Behaviour Science 93: 199-211.
Day, J. E. L. et al. 2002. The effects of prior experience of straw and the level of straw
provision on the behaviour of growing pigs. Applied Animal Behaviour Science 76:
189-202.
Day, J. E. L., I. Kyriazakis, and A. B. Lawrence. 1996. An investigation into the causation of
chewing behaviour in growing pigs: The role of exploration and feeding motivation.
Applied Animal Behaviour Science 48: 47-59.
Day, J. E. L., H. A. Van de Weerd, and S. A. Edwards. 2008. The effect of varying lengths of
straw bedding on the behaviour of growing pigs. Applied Animal Behaviour Science
109: 249-260.
Di Martino, G. et al. 2015. The effect of tail docking on the welfare of pigs housed under
challenging conditions. Livestock Science 173: 78-86.
EFSA. 2007. Scientific report on the risks associated with tail biting in pigs and possible
means to reduce the need for tail docking considering the different housing and
husbandry systems. The EFSA Journal 611: 1-13.
EUWelNet. 2013. http://euwelnet.hwnn001.topshare.com/. 10 November 2015.
24
Groffen, J. 2012. Tail posture and motion as a possible indicator of emotional state in pigs.
Student report / Swedish University of Agricultural Sciences, Department of Animal
Environment and Health 393.
Hansen, L. L., A. M. Hagelsø, and A. Madsen. 1982. Behavioural results and performance of
bacon pigs fed ad libitum from one or several self-feeders. Applied Animal Ethology
8: 307-333.
Harley, S. et al. 2014. Docking the value of pigmeat? Prevalence and financial implications of
welfare lesions in irish slaughter pigs. Animal Welfare 23: 275-285.
Hötzel, M. J., G. P. P. de Souza, O. A. D. Costa, and L. C. P. Machado Filho. 2011.
Disentangling the effects of weaning stressors on piglets' behaviour and feed intake:
Changing the housing and social environment. Applied Animal Behaviour Science
135: 44-50.
Huey, R. J. 1996. Incidence, location and interrelationships between the sites of abscesses
recorded in pigs at a bacon factory in northern ireland. The Veterinary record 138:
511-514.
Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 1999. Tail biting in pigs
1: The prevalence at six uk abattoirs and the relationship of tail biting with docking,
sex and other carcass damage. Pig Journal (United Kingdom).
Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 2001. The relationship
between tail biting in pigs, docking procedure and other management practices. The
Veterinary Journal 161: 72-79.
Jensen, M. B., I. Kyriazakis, and A. B. Lawrence. 1993. The activity and straw directed
behaviour of pigs offered foods with different crude protein content. Applied Animal
Behaviour Science 37: 211-221.
Keeling, L. J., A. Wallenbeck, A. Larsen, and N. Holmgren. 2012. Scoring tail damage in
pigs: An evaluation based on recordings at swedish slaughterhouses. Acta Veterinaria
Scandinavica 54: 1-6.
Kritas, S. K., and R. B. Morrison. 2004. An observational study on tail biting in commercial
grower-finisher barns. Journal of Swine Health and Production 12: 17-22.
Kritas, S. K., and R. B. Morrison. 2007. Papers & articles. The Veterinary record 160: 149-
152.
25
Kutzer, T., B. Bünger, J. B. Kjaer, and L. Schrader. 2009. Effects of early contact between
non-littermate piglets and of the complexity of farrowing conditions on social
behaviour and weight gain. Applied Animal Behaviour Science 121: 16-24.
Lallès, J.-P., P. Bosi, H. Smidt, and C. R. Stokes. 2007. Weaning - a challenge to gut
physiologists. Livestock Science 108: 82-93.
Li, Y., and L. Wang. 2011. Effects of previous housing system on agonistic behaviors of
growing pigs at mixing. Applied Animal Behaviour Science 132: 20-26.
McGlone, J. J., J. Sells, S. Harris, and R. J. Hurst. 1990. Cannibalism in growing pigs: Effects
of tail docking and housing system on behaviour, performance and immune function.
Texas Tech Univ Agric Sci Tech Rep: 69-71.
Moinard, C., M. Mendl, C. J. Nicol, and L. E. Green. 2003. A case control study of on-farm
risk factors for tail biting in pigs. Applied Animal Behaviour Science 81: 333-355.
Munsterhjelm, C. et al. 2009. Experience of moderate bedding affects behaviour of growing
pigs. Applied Animal Behaviour Science 118: 42-53.
Nannoni, E., T. Valsami, L. Sardi, and G. Martelli. 2014. Tail docking in pigs: A review on
its short- and long-term consequences and effectiveness in preventing tail biting.
Italian Journal of Animal Science 13.
NMELV. 2015. Niedersächsisches Ministerium für Ernährung Landwirtschaft und
Verbraucherschutz, gemeinsame Eckpunkte zur Tierwohlförderung.
Oostindjer, M., J. E. Bolhuis, H. van den Brand, E. Roura, and B. Kemp. 2010. Prenatal
flavor exposure affects growth, health and behavior of newly weaned piglets.
Physiology & Behavior 99: 579-586.
Palander, P. A., M. Heinonen, I. Simpura, S. A. Edwards, and A. E. Valros. 2013. Jejunal
morphology and blood metabolites in tail biting, victim and control pigs. Animal 7:
1523-1531.
Parker, M. O. et al. 2010. The impact of chronic environmental stressors on growing pigs, sus
scrofa (part 2): Social behaviour. Animal 4: 1910-1921.
Petersen, V., H. B. Simonsen, and L. G. Lawson. 1995. The effect of environmental
stimulation on the development of behaviour in pigs. Applied Animal Behaviour
Science 45: 215-224.
26
Rodenburg, T. B., and P. Koene. 2007. The impact of group size on damaging behaviours,
aggression, fear and stress in farm animals. Applied Animal Behaviour Science 103:
205-214.
Schmolke, S. A., Y. Z. Li, and H. W. Gonyou. 2003. Effect of group size on performance of
growing-finishing pigs. J. Anim. Sci. 81: 874-878.
Schrøder-Petersen, D. L., T. Heiskanen, and A. K. Ersboll. 2004. Tail-in-mouth behaviour in
slaughter pigs, in relation to internal factors such as: Age, size, gender, and
motivational background. Acta Agriculturae Scandinavica Section a-Animal Science
54: 159-166.
Schrøder-Petersen, D. L., H. B. Simonsen, and L. G. Lawson. 2003. Tail-in-mouth behaviour
among weaner pigs in relation to age, gender and group composition regarding gender.
Acta Agriculturae Scandinavica Section a-Animal Science 53: 29-34.
Scott, K., L. Taylor, B. P. Gill, and S. A. Edwards. 2007. Influence of different types of
environmental enrichment on the behaviour of finishing pigs in two different housing
systems: 2. Ratio of pigs to enrichment. Applied Animal Behaviour Science 105: 51-
58.
Simonsen, H. B., L. Klinken, and E. Bindseil. 1991. Histopathology of intact and docked
pigtails. British Veterinary Journal 147: 407-412.
Sinisalo, A., J. K. Niemi, M. Heinonen, and A. Valros. 2012. Tail biting and production
performance in fattening pigs. Livestock Science 143: 220-225.
Sneddon, I. A., V. E. Beattie, N. Walker, and R. N. Weatherup. 2001. Environmental
enrichment of intensive pig housing using spent mushroom compost. Animal Science
72: 35-42.
Statham, P., L. Green, M. Bichard, and M. Mendl. 2009. Predicting tail-biting from behaviour
of pigs prior to outbreaks. Applied Animal Behaviour Science 121: 157-164.
Statham, P., L. Green, and M. Mendl. 2011. A longitudinal study of the effects of providing
straw at different stages of life on tail-biting and other behaviour in commercially
housed pigs. Applied Animal Behaviour Science 134: 100-108.
Stolba, A., and D. G. M. Wood-Gush. 1989. The behaviour of pigs in a semi-natural
environment. Animal Science 48: 419-425.
27
Studnitz, M., M. B. Jensen, and L. J. Pedersen. 2007. Why do pigs root and in what will they
root?: A review on the exploratory behaviour of pigs in relation to environmental
enrichment. Applied Animal Behaviour Science 107: 183-197.
Taylor, N. R., D. C. J. Main, M. Mendl, and S. A. Edwards. 2010. Tail-biting: A new
perspective. The Veterinary Journal 186: 137-147.
Taylor, N. R., R. M. A. Parker, M. Mendl, S. A. Edwards, and D. C. J. Main. 2012.
Prevalence of risk factors for tail biting on commercial farms and intervention
strategies. The Veterinary Journal 194: 77-83.
Telkänranta, H., K. Swan, H. Hirvonen, and A. Valros. 2014. Chewable materials before
weaning reduce tail biting in growing pigs. Applied Animal Behaviour Science 157:
14-22.
TierSchG. 2006. Tierschutzgesetz in der Fassung der Bekanntmachung vom 18. Mai 2006
(BGBl. I s. 1206, 1313), das durch Artikel 3 des Gesetzes vom 28. Juli 2014 (BGBl. I
s. 1308) geändert worden ist.
TierSchNutztV. 2006. Tierschutz-Nutztierhaltungsverordnung in der Fassung der
Bekanntmachung vom 22. August 2006 (BGBl. I s. 2043), die zuletzt durch Artikel 1
der Verordnung vom 5. Februar 2014 (BGBl. I s. 94) geändert worden ist.
Ursinus, W. W., C. G. Van Reenen, B. Kemp, and J. E. Bolhuis. 2014. Tail biting behaviour
and tail damage in pigs and the relationship with general behaviour: Predicting the
inevitable? Applied Animal Behaviour Science 156: 22-36.
Van de Weerd, H. A., C. M. Docking, J. E. L. Day, P. J. Avery, and S. A. Edwards. 2003. A
systematic approach towards developing environmental enrichment for pigs. Applied
Animal Behaviour Science 84: 101-118.
Van de Weerd, H. A. V. d., C. M. Docking, J. E. L. Day, K. Breuer, and S. A. Edwards. 2006.
Effects of species-relevant environmental enrichment on the behaviour and
productivity of finishing pigs. Applied Animal Behaviour Science 99: 230-247.
Veit, C., I. Traulsen, K. Müller, K.-H. Tölle, and J. Krieter. 2014. Einfluss einer
Raufuttergabe auf das Auftreten von Schwanzbeißen in der Ferkelaufzucht.
Vortragstagung der DGfZ und GfT am 17./ 18. September 2014 in Dummerstorf, B22.
Walker, P. K., and G. Bilkei. 2006. Tail-biting in outdoor pig production. The Veterinary
Journal 171: 367-369.
28
Widowski, T. 2002. Causes and prevention of tail biting in growing pigs: A review of recent
research. In: London Swine Conference - Conquering the Challenges. London,
Ontario. p 47-56.
Zonderland, J. J., M. B. M. Bracke, L. A. den Hartog, B. Kemp, and H. A. M. Spoolder.
2010a. Gender effects on tail damage development in single- or mixed-sex groups of
weaned piglets. Livestock Science 129: 151-158.
Zonderland, J. J., B. Kemp, M. B. M. Bracke, L. A. den Hartog, and H. A. M. Spoolder. 2011.
Individual piglets' contribution to the development of tail biting. Animal 5: 601-607.
Zonderland, J. J. et al. 2010b. Characteristics of biter and victim piglets apparent before a tail-
biting outbreak. Animal 5: 767-775.
Zonderland, J. J. et al. 2009. Tail posture predicts tail damage among weaned piglets. Applied
Animal Behaviour Science 121: 165-170.
Zonderland, J. J. et al. 2008. Prevention and treatment of tail biting in weaned piglets.
Applied Animal Behaviour Science 110: 269-281.
Zwicker, B., L. Gygax, B. Wechsler, and R. Weber. 2013. Short- and long-term effects of
eight enrichment materials on the behaviour of finishing pigs fed ad libitum or
restrictively. Applied Animal Behaviour Science 144: 31-38.
29
MATERIAL AND METHODS
Data collection
Data collection was carried out on the research farm of the Chamber of Agriculture of
Schleswig-Holstein (Futterkamp), Germany, between September 2013 and April 2014.
In the environmental enrichment study, 721 crossbreed piglets (Pietrain x (Large White x
Landrace)) from 60 litters were used in ten batches. Each batch corresponded to a farrowing
week. The piglets had an average birth weight of 1.4 ± 0.3 kg. The suckling period took place
in conventional farrowing systems (5.2 m² per pen), tails were not docked and males were not
castrated. From the second week of life until weaning, the piglets received a pre-starter diet
(14.6 MJ ME, 17.5 % protein, 1.45 % lysine, 0.25 % sodium). The piglets were weaned with
on average 28 days with an average weight of 8.0 ± 1.7 kg. Rearing lasted for 40 days until an
average weight of 25.4 ± 2.3 kg. The piglets were housed in mixed gender groups consisting
of one or two litters (12 or 24 piglets per pen) with an average space allowance of 0.38 or
0.42 m² per animal. According to the units the feeding system was either mash or dry feed ad
libitum with an animal to feeding place ratio of 2:1. For the first two weeks of rearing, the
piglets received a starter diet (14.4 MJ ME, 18.0 % protein, 1.40 % lysine, 0.20 % sodium),
thereafter the diet was gradually changed over the next four days and fed until day 40 of
rearing (13.4 MJ ME, 17.0 % protein, 1.30 % lysine, 0.25 % sodium). The drinking system
consisted of nipples and bowls, the floor was fully slatted and no bedding material was
offered. Plastic sticks, plastic balls and hard wooden sticks were provided as enrichment
material. The environmental temperature during rearing was automatically regulated by
forced ventilation. It was set at 29.5 °C on day one and decreased stepwise until 22.0 °C on
day 40. The animals had full artificial lighting between 06:00 h and 18:00 h.
In the weaning management study, 478 crossbreed piglets (Pietrain x (Large White x
Landrace)) from 40 litters were used in five batches. Tails were not docked and males were
not castrated. The piglets were weaned with on average 28 days with an average weaning
weight of 8.3 ± 1.6 kg. Five identical rearing units consisting of eight pens each were
consecutively used. Rearing lasted for 40 days in mixed gender groups until an average
weight of 25.9 ± 3.8 kg. The groups consisted of 12 piglets per pen with a space allowance of
0.38 m²/ animal. The feeding system used was mash feed ad libitum with an animal to feeding
30
place ratio of 2:1 and a diet composition of 17.0 % protein, 1.3 % lysine, 0.7 % calcium and
0.25 % sodium (13.4 MJ ME). Water was accessible through nipple drinkers. The floor was
fully slatted and no bedding material was provided. One plastic ball per pen (suspended on a
metal chain) and alfalfa hay in plastic bowls (one per pen, Ø 40 cm, animal to occupation
place ratio 1.2:1) was provided as environmental enrichment material. The environmental
temperature was automatically regulated by forced ventilation. It was set at 28.0 °C on day
one of rearing and decreased stepwise until 24.0 °C on day 40. The animals had full artificial
lighting between 06:00 h and 19:00 h.
Experimental design
In the environmental enrichment study, 721 piglets were divided randomly into three groups
litter-wise: a control group (CG) with 231 long-tailed piglets (♂ 121, ♀ 110), housed without
raw material, a dried corn silage group (SG, ♂ 124, ♀ 121) and an alfalfa hay group (AG,
♂ 117, ♀ 128) with 245 long-tailed piglets each. In the farrowing units, 20 litters were used
for each treatment, two litters of each treatment group (n = 3) per batch (n = 10) respectively.
After weaning, the piglets were housed either litter-wise or two litters were mixed, resulting
in 14 pens for each treatment with two different group sizes in the rearing units (12 or 24
piglets per pen). Within each of the ten batches, the number of CG, SG, and AG pens was
balanced and the locations of the treatment groups within the units were randomised.
In the weaning management study, 478 piglets were divided randomly into two groups, 240
piglets (♂ 124, ♀ 116) were housed in litter groups (LG), whereas 238 piglets (♂ 117, ♀ 121)
were mixed from at least three different litters (MG). Each unit consisted of four pens with
LGs and four pens with MGs, resulting in 20 pens for each treatment. The locations of the
treatment groups within the unit were randomised.
Treatments
In the environmental enrichment study raw material was provided twice a day (in the morning
and in the afternoon) from the second week of life until the end of rearing in the piglet nest
(Fig. 1) or in a piglet bowl (Fig. 2). During rearing the animal to occupation place ratio was
either 1.2:1 (12 piglets/ pen) or 2.4:1 (24 piglets/ pen). The amount of dried corn silage
offered per day and pen was about 100 g, the amount of alfalfa hay about 120 g/ day/ pen,
31
which corresponds to a handful of material per offer. In pens affected by tail-biting, the
intervention scheme was a jute bag (fixed on the pen wall), long, chopped straw on the pen
floor, grass silage or straw-peat mixture provided in piglet bowls. In severe cases, identified
biters were removed from the pen. Treatment with intervention material was also applied in
CG pens if an outbreak occurred.
Figure 1: Raw material treatment (AG)
in piglet nest (farrowing).
Figure 2: Raw material treatment (AG) in
piglet bowl (Ø 40 cm, rearing)
Scoring
Tail lesions were scored weekly during farrowing (environmental enrichment study only) and
rearing. The scoring scheme (modified from Abriel and Jais, 2013) classifies the severity of
tail lesions with a four-point score consisting of “no visible damage“, “scratches, light bite
marks“, “moderate damage” (Fig. 3) and “severe damage” (Fig. 4). A tail-biting outbreak was
defined as an instance where at least one piglet showed a freshly bleeding tail wound or a loss
of the tail. Tail losses were classified by “original length of tail”, “loss of tail tip” (Fig. 5),
“partial loss” (Fig. 6) and “total loss” (Fig. 6). Furthermore, the gender and the size of the
animals (small, medium, large, in relation to pen mates) were recorded.
32
Figure 3: Moderate damage
Figure 4: Severe damage
Figure 5: Loss of tail tip Figure 6: Partial losses in the back and
total losses in the front
Weight gain
In the environmental enrichment study, weight was collected at pen level (n = 27) at the
beginning and end of rearing. In the weaning management study, individual body weights of
the piglets (n = 478) were collected at weaning, at day 16 and at day 40 of rearing.
Video surveillance
In the environmental enrichment study, three farrowing units and three rearing units were
equipped with colour cameras (Santec, VTC-249IRP/ W or VTC-279IRPWD). In total, 99
piglets during farrowing (five pens of AGs, three pens of SGs) and 188 piglets during rearing
(four pens for each treatment group) were video recorded 24 hours every day (Fig. 7). The
HeitelPlayer software (Xtralis Headquarter D-A-CH, HeiTel Digital Video GmbH, Kiel,
33
Germany) was used to watch the videos. Six different behavioural patterns during farrowing
and ten different behavioural patterns during rearing were coded (Tab. 1). The time budgets of
each animal were investigated by instantaneous scan sampling with a 10 min interval from
06:00 h to 18:00 h. Additionally, a one-minute sampling interval was used for the first 10
minutes after raw material provision to determine the number of piglets occupied by the
material.
In the weaning management study, 32 pens (four units) were equipped with colour cameras
and recorded 24 hours per day (Santec, VTC-249/ IRP/ W or VTC-279/ IRPWD). The piglets
were individually marked with colour spray three times per week (Fig. 8). The open source
software BORIS (Friard, 2014) was used for the video analysis of five pens (three MGs, two
LGs). In total 60 piglets (♂ 29, ♀ 31) were analysed regarding five days prior to a scored tail-
biting outbreak and on the day of an outbreak itself. Eleven different behavioural patterns
were coded (Tab. 2).
Figure 7: Video observation in the
environmental enrichment
study (farrowing).
Figure 8: Video observation in the
weaning management study
(rearing).
34
Table 1: Ethogram used for video observation in the environmental enrichment study.
Behaviour Description
Lying Lying on the side or ventrally
Sitting Body supported by hind-quarters and stretched front legs
Standing Body supported by four stretched legs, includes
locomotion
Feeding Head positioned in the feeder
Occupation with raw material Sniffing, nosing or rooting the raw material in piglet
bowl/ nest
Occupation with toys Head on the toys
Additionally observed during
rearing
Tail exploration
Head on the back side of a pen mate, includes tail-in-
mouth and tail-biting behaviour
Drinking Head on the water nipple
Belly nosing Manipulation of the abdomen of a lying pen mate
Occupation with intervention
material
Head on the additional offered material (in case of tail-
biting outbreaks)
35
Table 2: Ethogram used for video observation in the weaning management study.
Behavioural pattern Description
Instantaneous scan sampling
Lying Lying on the side or ventrally
Standing Body supported by four stretched legs, includes
locomotion
Feeding Head positioned in the feeder
Occupation with raw material Sniffing, nosing or rooting the raw material in piglet bowl
Pen investigation Head on the pen surrounding (floor and walls)
Continuously collected
Tail exploration
Performer Head on the tail of a pen mate, includes tail-in-mouth and
tail-biting behaviour
Receiver Being manipulated by a pen mate on the tail, includes
tail-in-mouth and tail-biting behaviour
Belly nosing
Performer Manipulation of the abdomen of a lying pen mate
Receiver Being manipulated by a pen mate on the abdomen, while
lying
Nosing
Performer Snout contact with any part of the body of a pen mate
except the belly region
Receiver Being contacted by snout on any part of the body, except
the belly region
36
The time budgets of each animal were investigated by instantaneous scan sampling over 20
minutes from every second hour between 06:00 h and 18:00 h (06:00 h to 06:20 h, 08:00 h to
08:20 h, 10:00 h to 10:20 h, 12:00 h to 12:20 h, 14:00 h to 14:20 h, 16:00 h to 16:20 h and
18:00 h to 18:20 h), the sampling scheme was every 2 minutes. Every 20 min interval is
counted as a scan, resulting in 42 scans per pen over six days, respectively 210 scans in total.
Due to technical difficulties, there was a lack of 17 scans, thus, the data was limited to 193
scans. Additionally, the manipulative behavioural patterns tail exploration (te), belly nosing
(bn) and nosing (no) were recorded continuously over the above-mentioned time frame to
determine the receivers (R) and performers (P) of each behaviour. In order to make piglets’
behaviour comparable and classifiable, the frequencies of the recorded manipulative
behavioural patterns required a conversion into scores/ indices. The character score (CS) was
developed to assign a number to each piglet (i), defining it as a receiver or performer by
changing the algebraic sign. The following formula defines CS, where x ∈ {te, bn, no}, y ∈
{1, 2, 3, 4, 5} and i ∈ {1,…,60}:
CSx,y (i) = [Px(i)/ max_Px,y] - [Rx(i)/ max_Rx,y] (1)
Px(i) is the number of manipulative contacts as a performer of behaviour x for piglet i and
max_Px,y is the maximum number of manipulative performer contacts in pen y. Rx(i) is the
number of manipulative contacts as a receiver of behaviour x for piglet i and max_Rx,y is the
maximum number of manipulative contacts as a receiver in pen y. CS ranges between -1
(absolute receiver) and +1 (absolute performer);
In order to determine ranges (upper limit (UL) and lower limit (LL)) for CS to assign piglets
to different character categories, the following formulas were used:
ULx,y = MWx,y + 0.52 x std x,y (2)
LLx,y = MWx,y – 0.52 x std x,y (3)
MWx,y denote the mean and std x,y denote the standard deviation of CS x,y. The constant 0.52 is
the 70 %-quantile of the standard normal distribution. Piglets with CSs within the range of UL
and LL were named as “neutral”. Piglets with CSs which exceeded the UL were named as
“performer” and piglets with CSs which fell below the LL were named as “receiver”.
37
Statistical procedures
The software package SAS 9.2® was used for statistical analysis (SAS, 2008). The fit
statistics AICC “Akaike’s information criterion corrected” (Hurvich and Tsai, 1989) and the
BIC “Bayesian information criterion” (Schwarz, 1978) were used to evaluate the fitting of the
models. Fixed effects were added stepwise to the models. The model with the smallest AICC
and BIC was chosen for the analysis.
Environmental enrichment study
The data of tail lesions and tail losses followed a multinomial distribution (Score 0-3).
Therefore, the procedure GLIMMIX was used assuming a cumulative logit link function for
the multinomial distributed data. Due to the fact that tail-biting did not occur during
farrowing, the data for the statistical analysis was limited to the rearing period. The
experimental unit was the pen. The fixed effects group (CG, SG, AG), batch (1-10), week
after weaning (1-6) and the interaction of group and batch were used in the final model for tail
lesions. The pen (nested in batch) was included as a random effect. Only the last observation
at the end of rearing was taken into consideration regarding tail losses. The group (CG, SG,
AG) and the batch (1-10) were used as fixed effects in the final model for tail losses.
The MIXED procedure was used in order to estimate the effect of tail-biting on total weight
gain during rearing. For every treatment group and scoring scheme (tail lesions and tail
losses) nine pens were ranked regarding the total number of piglets with a score higher than
Score 0 within each pen, resulting in three pens for a low, respectively medium and high level
of tail lesions and tail losses (only last observation was taken into consideration). The level of
tail lesions/ tail losses (low, medium, high), the treatment group (CG, SG, AG) and the
interaction between level of tail lesions/ tail losses and treatment group were used as fixed
effects. Significant differences in the least-square-means were adjusted with the Bonferroni-
correction (p < 0.05) (Westfall et al., 2011).
The trait occupation with the raw material provided was investigated with two models
(farrowing, rearing). Occupation was coded as a binary trait (0: not occupied, 1: occupied).
The procedure GLIMMIX was used with the link function logit. The fixed effects group (SG,
AG), batch (1-3), day after first raw material provision (1-16) and the interaction between
group and day after first raw material provision were used in the final model for farrowing.
38
The fixed effects group (SG, AG), batch (1-3), day after weaning (1-28) and the interaction
between group and day after weaning were used in the final model for rearing. The pen
(nested within batch) was included as a random effect in both models.
The trait activity behaviour was analysed with one model. Due to the low frequencies of the
behavioural patterns occupation with raw material and toys, tail exploration, drinking and
belly nosing, they were summarised as “active”, together with sitting, standing and feeding.
Lying behaviour was counted as “inactive” in further analysis. The activity behaviour was
coded as a binary trait, the procedure GLIMMIX was used with the link function logit. The
fixed effects group (CG, SG, AG), batch (1-3), day after weaning (1-28), daytime (6-18h), the
interaction of group and day after weaning, as well as the interaction of batch and day after
weaning were used in the final model. The pen was included as a random effect.
Weaning management study
The data of tail lesions and tail losses followed a multinomial distribution (Scores 0-3). Thus,
the GLIMMIX procedure was used assuming a cumulative logit link function for the
multinomial distributed data. The fixed effects treatment group (LG, MG), week after
weaning (1-6), batch (1-5) and the interaction of treatment group and batch were added
stepwise and used as fixed effects in the final model for tail lesions. The piglet was included
as a random effect and was nested within group and batch. The database was limited to the
last observation at the end of rearing regarding tail losses. The fixed effects group (LG, MG)
and batch (1-5) and the interaction of group and batch were used as fixed effects in the final
model for tail losses.
In order to estimate the effect of tail-biting on daily weight gain the MIXED procedure was
used. Daily weight gain of three time periods was analysed: weaning to day 16 (period 1), day
16 to day 40 (period 2) and weaning to day 40 (period 3). The scores of tail lesions on day 16
and day 40, as well as the scores of tail losses on day 40 of rearing were classified by
distribution: class 0 (0), class 1 (1) and class 2 (2, 3) for tail lesions, as well as class 0 (0) and
class 1 (1, 2, 3) for tail losses. Low frequencies of tail losses in the study did not allow the
distinction into three classes, which may confound the gradations. Classes of tail lesions (0, 1,
2) on day 16 were added as fixed effects to the model for period 1, whereas classes of tail
lesions and tail losses on day 40 were added as fixed effects to the model for period 2 and
39
period 3. Period 1 was not analysed for tail losses, because they were observed not until four
weeks after weaning. The treatment group (MG, LG), the batch (1-5), the interaction of group
and batch and the gender were used as fixed effects in all models. Weaning weight was added
as covariable to the final models. Significant differences in the least-square-means were
adjusted with the Bonferroni-correction (p < 0.05) (Westfall et al., 2011).
Video data was limited to five pens, because continuously observation of manipulative
behavioural patterns required a high time effort due to the required assignment of performer
and receiver of each interaction. Therefore, the treatment groups (LGs, MGs) were not
considered in further statistical analysis. The count data of the continuously observed
manipulative behavioural patterns was analysed using the GLIMMIX procedure with a
Poisson-distribution. The fixed effects day (- 5, - 4, - 3, - 2, - 1, 0), daytime (6, 8, 10, 12, 14,
16, 18) and pen (1-5) were used in the models for tail exploration, belly nosing and nosing.
The piglet (nested within pen) was added as a random effect to the final models. The
accumulated frequencies of the behaviours lying, standing and feeding, which were observed
by instantaneous scan sampling of each piglet over six days (every 20 min of every second
hour from 06.00 h to 18.00 h), were analysed using the MIXED procedure. The behaviours
pen investigation and occupation with provided material were rarely shown by the piglets,
thus, not considered in further statistical analysis. Three different models were used to test the
effect of character (calculated by formulas 1 to 3) separately for tail exploration, belly nosing
and nosing. The character of the piglets (performer, neutral, receiver) for the respective
manipulative behavioural pattern and the pen (1-5) were used as fixed effects in the models
for lying, standing and feeding behaviour. Daily weight gain was added as a covariable to the
final models. The gender was removed from the models due to low improvements of the
fitting and no significant impact. Significant differences in the least-square-means were
adjusted with the Bonferroni-correction (p < 0.05) (Westfall et al., 2011).
References
Abriel, M., and C. Jais. 2013. Influence of housing conditions on the appearance of
cannibalism in weaning piglets. Landtechnik 68: 389-393.
Friard, O. 2014. Behavioral observation research interactive software.
http://penelope.unito.it/boris/.
40
Hurvich, C. M., and C.-L. Tsai. 1989. Regression and time series model selection in small
samples. Biometrika 76: 297-307.
SAS. 2008. SAS Institute Inc. Cary, NC, USA.
Schwarz, G. 1978. Estimating the dimension of a model. The annals of statistics 6.2: 461-464.
Westfall, P. H., R. D. Tobias, and R. D. Wolfinger. 2011. Multiple comparisons and multiple
tests using SAS. SAS Institute.
41
CHAPTER ONE
Influence of raw material on the occurrence of tail-biting in undocked pigs
Christina Veit1, Imke Traulsen1, Karl-Heinz Tölle2, Karin Müller3, Elisabeth grosse Beilage4,
Joachim Krieter1
1Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Kiel, Germany
2ISN-Projekt GmbH, Damme, Germany
3Chamber of Agriculture, Schleswig-Holstein, LVZ Futterkamp, Blekendorf, Germany
4Field Station for Epidemiology, University of Veterinary Medicine, Hannover, Germany
Submitted to Livestock Science
42
Abstract
The aim of this study was to reveal the effects of raw material provision on tail-biting
outbreaks in long-tailed pigs. Two different substrates, dried corn silage (SG, n = 245) and
alfalfa hay (AG, n = 245) were provided for the pigs twice per day from the second week of
life until the end of rearing. The control of long-tailed pigs (CG, n = 231) were kept without
the provision of additional raw material. Each tail was scored regarding tail lesions/ tail losses
once per week with a four-point score (0 = no damage/ original length to 3 = severe damage/
total loss). The effect of week after weaning and the interaction of group and batch had highly
significant influences on tail lesions (p < 0.001). The main concentration of behavioural
disorder took place in the rearing phase. Tail-biting started on average two to three weeks
after weaning, followed by tail losses one to two weeks later. The effects of batch and group
had highly significant influences on tail losses at the end of rearing (p < 0.001). The number
of tail losses decreased with the number of batches and ranged from 96.4 % in batch one to
7.4 % in batch ten. This can be explained by enhanced and more precise animal observation
by stable staff and points out the learning process in the course of the study. At the end of
rearing, piglets of all batches had lost their tails to the greatest extent in CGs (50.4 %),
followed by AGs (49.2 %) and SGs (30.2 %). There was no clear trend in total weight gain
regarding the level of tail lesions and tail losses. Corn silage stayed attractive for the piglets
during the whole observation period, whereas the acceptance of the alfalfa hay decreased
towards the end of rearing. The daytime, the interaction of batch and day after weaning, as
well as the interaction of group and day after weaning had highly significant influences on the
overall activity behaviour during rearing (p < 0.001). There was no clear trend between
activity behaviour and the level of tail-biting within the batches. To summarise, the rearing of
long-tailed pigs requires intensive animal observation and direct intervention in case of tail-
biting outbreaks. A provision of raw material on the floor of the piglet nest (suckling period)
and in a piglet bowl (rearing period) from the second week of life until the end of rearing
cannot prevent behavioural disorder during rearing and precise surveillance is indispensable
to avoid severe tail losses.
43
1. Introduction
Tail-biting in pigs is a welfare concern in intensive pig husbandry and leads to economic
losses (EFSA, 2007). The multifactorial background makes it difficult to deal with the
problem. Higher stocking densities and deficiencies in feed quality or accessibility (Moinard
et al., 2003), poor ventilation (Hunter et al., 2001) as well as a lack of rooting substrate
(Zonderland et al., 2008) have been identified as environmental risk factors. On the biological
side, poor health (Day et al., 2002), breed (Breuer et al., 2003) and gender (Zonderland et al.,
2010a) could also play a role. The pigs’ need to perform exploration and foraging behaviour
is considered to be a major underlying motivation for tail-biting (EFSA, 2007). It should to be
taken into consideration that pigs in the wild spend more than 70 % of their daily activity with
these behavioural patterns, which can be expressed only to a minor extent in the barren
conditions of intensive housing systems. When suitable material is unavailable, pigs may
redirect their search behaviour towards other pigs and the pen’s surroundings (EFSA, 2007).
In accordance with the EU Directive (2008/ 120/ EG), pigs must have permanent access to a
sufficient quantity of material to enable proper investigation and manipulation activities, such
as straw, hay, wood, sawdust, mushroom compost or peat. However, under practical
conditions in Germany environmental enrichment is guaranteed mainly by plastic toys or
metal chains; even though the absence of particulate, rootable substrate has already been
identified as a significant hazard leading to tail-biting (EFSA, 2007).
Tail-biting as a form of cannibalism is not a new phenomenon. Since the intensification of pig
production in the 1950s, it has turned out to be a problem and until now tail-docking has been
the most efficient way to avoid it. Under common intensive farming conditions, tail-docking
reduces the frequency of tail-biting, but does not completely eliminate the problem when
unfavourable conditions persist (EFSA, 2007). However, European law (2001/ 93/ EG)
prohibits the routine docking of pig tails and it is realised under practical conditions using
veterinary case permissions. In order to turn away from this procedure towards the integrity of
the animals’ body and improvements in animal welfare, there is a need for intensive research
into docking alternatives. An important approach to minimise the risk for tail-biting is the
offer of manipulable material (Zonderland et al., 2008). It has been proved that environmental
enrichment reduces time spent involved in harmful social and aggressive behaviour (Beattie et
al., 2000). Several studies have shown a reduction in tail-biting behaviour through
44
environmental enrichment with straw (Day et al., 2008; Van de Weerd et al., 2006) or other
material which can be rooted by the animals (Sneddon et al., 2001). These studies focused on
the observation of pigs in fattening units, whereas recent studies have shown that behavioural
disorder among long-tailed pigs occurs in rearing units (Abriel and Jais, 2013). Furthermore,
it has been pointed out recently that pre-weaning enrichment could have effects on tail-biting
behaviour in later life (Oostindjer et al., 2010; Telkänranta et al., 2014 ). The aim of this study
was to reveal the effects of raw material provision from the second week of life until the end
of rearing on tail lesions and tail losses. Thus, the substrates dried corn silage and alfalfa hay
were used to enable the piglets to perform their natural exploration and foraging behaviour.
Furthermore, the intensity and duration of occupation with the material provided and the
different behavioural patterns of the piglets were analysed by video observation.
2. Materials and methods
2.1. General aspects
The pigs in the present study were kept on the research farm of the Chamber of Agriculture of
Schleswig-Holstein (Futterkamp), Germany, in accordance with EU Directive (2008/ 120/
EG) and in accordance with the Tierschutz-Nutztierhaltungsverordnung (TierSchNutztV,
2006). In case of tail-biting outbreaks, manipulable material was provided in control pens as
well to avoid endangerment of animal welfare.
2.2. Animals and housing
Data collection was carried out between September 2013 and April 2014. Farrowing and
rearing followed conventional farming practices; the farm size was 400 sows and 2,500
rearing places. In the present study, 721 crossbreed piglets (Pietrain x (Large White x
Landrace)) from 60 litters were housed in ten batches. Each batch corresponded to a
farrowing week. The piglets had an average birth weight of 1.4 ± 0.3 kg. The suckling period
took place in conventional farrowing systems (5.2 m² per pen), tails were not docked and
males were not castrated. From the second week of life until weaning, the piglets received a
pre-starter diet (14.6 MJ ME, 17.5 % protein, 1.45 % lysine, 0.25 % sodium). The piglets
were weaned with on average 28 days with an average weaning weight of 8.0 ± 1.7 kg.
45
Rearing lasted for 40 days until an average weight of 25.4 ± 2.3 kg. The piglets were housed
in mixed gender groups consisting of one or two litters (12 or 24 piglets per pen) with an
average space allowance of 0.38 or 0.42 m² per animal. According to the units, the feeding
system was either mash or dry feed ad libitum with an animal to feeding place ratio of 2:1.
For the first two weeks of rearing the piglets received a starter diet (14.4 MJ ME, 18.0 %
protein, 1.40 % lysine, 0.20 % sodium), thereafter the diet was gradually changed over the
next four days and fed until day 40 of rearing (13.4 MJ ME, 17.0 % protein, 1.30 % lysine,
0.25 % sodium). The drinking system consisted of nipples and bowls, the floor was fully
slatted and no bedding material was offered. Plastic sticks, plastic balls and hard wooden
sticks were provided as enrichment material. The environmental temperature during rearing
was automatically regulated by forced ventilation. It was set at 29.5 °C on day one of rearing
and decreased stepwise until 22.0 °C on day 40. The animals had full artificial lighting
between 06:00 h and 18:00 h.
2.3. Experimental design
In total, 721 piglets were divided randomly into three groups litter-wise: a control group (CG)
with 231 long-tailed piglets housed without raw material, a dried corn silage group (SG) and
an alfalfa hay group (AG) with 245 long-tailed piglets each. In the farrowing units, 20 litters
were used for each treatment, two litters of each treatment group (n = 3) per batch (n = 10)
respectively. After weaning, the piglets were housed either litter-wise or two litters were
mixed, resulting in 14 pens for each treatment with two different group sizes in the rearing
units (12 or 24 piglets per pen). A schematic view of the experimental set-up during rearing is
given in Figure 1. Within each of the ten batches, the number of CG, SG, and AG pens was
balanced and the locations of the treatment groups within the units were randomised.
46
Figure 1: Schematic view of the experimental set-up regarding rearing.
2.4. Treatments
The provision of raw material took place from the second week of life until the end of rearing
twice a day (in the morning and in the afternoon) in the piglet nest (farrowing) or in a piglet
bowl (Ø 40 cm) with an animal to occupation place ratio of 1.2:1 (12 piglets/ pen) or 2.4:1 (24
piglets/ pen) during rearing.
The amount of dried corn silage offered per day and pen was about 100 g, the amount of
alfalfa hay about 120 g/ day/ pen, which corresponds to a handful of material per offer. In
pens affected by tail-biting, the intervention scheme was a jute sack (fixed on the pen wall), a
handful of long, chopped straw on the pen floor, grass silage or straw-peat mixture provided
in piglet bowls. In severe cases, identified biters were removed from the pen. Treatment with
intervention material was also applied in CG pens if an outbreak occurred.
2.5. Data collection
2.5.1. Scoring
Scoring of tail lesions and tail losses took place weekly during farrowing and rearing. The
scoring scheme (modified from Abriel and Jais, 2013) classified the severity of tail lesions
with a four-point score consisting of “no visible damage” (0), “scratches, light bite marks”
(1), “moderate damage” (2) and “severe damage” (3). A tail-biting outbreak was defined as a
point in time when at least one piglet showed a freshly bleeding tail wound or a loss of the
Total number
Treatment groups
Housing
Control (CG)
n = 231 (♀110, ♂121)
Corn silage (SG)
n = 245 (♀121, ♂124)
Alfalfa hay (AG)
n = 245 (♀128, ♂117)
Six batches with three pens
à 24 piglets
Four batches with six pens
à 12 piglets
n = 721, 60 litters
47
tail. Tail losses were classified by “original length of tail” (0), “loss of tail tip” (1), “partial
loss” (2) and “total loss” (3). Furthermore, the gender and the size of the animals (small,
medium, large, in relation to pen mates) were recorded.
2.5.2. Weight gain
Weight was collected at pen level in the beginning and in the end of rearing. Due to data
transmission problems group weights of only six batches (27 pens) were available. The pens
were equally distributed over the treatment groups.
2.5.3. Video surveillance
To investigate the activity behaviour of the animals and the duration of occupation with the
raw material, three farrowing units and three rearing units were equipped with colour cameras
(Santec, VTC-249IRP/ W or VTC-279/ IRPWD). In total, 99 piglets during farrowing (five
pens of AGs, three pens of SGs) and 188 piglets during rearing (four pens for each treatment
group) were video recorded 24 hours every day. The HeitelPlayer software (Xtralis
Headquarter D-A-CH, HeiTel Digital Video GmbH, Kiel, Germany) was used to watch the
videos. Six different behavioural patterns during farrowing and ten different behavioural
patterns during rearing were coded. The ethogram is given in Table 1. The time budgets of
each animal were investigated by instantaneous scan sampling with a 10 min interval from
06:00 h to 18:00 h. Additionally, a one-minute sampling interval was used for the first 10
minutes after raw material provision to determine the number of piglets occupied by the
material.
48
Table 1: Ethogram used for video observation in the 10 min sampling frame.
2.6. Statistical procedures
The software package SAS 9.2® was used for statistical analysis (SAS, 2008). The fit
statistics AICC “Akaike’s information criterion corrected” (Hurvich and Tsai, 1989) and the
BIC “Bayesian information criterion” (Schwarz, 1978) were used to evaluate the fitting of the
models. Fixed effects were added stepwise to the models. The model with the smallest AICC
and BIC was chosen for the analysis.
Behaviour Description
Lying Lying on the side or ventrally
Sitting Body supported by hind-quarters and stretched front legs
Standing Body supported by four stretched legs, includes
locomotion
Feeding Head positioned in the feeder
Occupation with raw material Sniffing, nosing or rooting the raw material in piglet
bowl/ nest
Occupation with toys Head on the toys
Additionally observed during
rearing
Tail exploration
Head on the back side of a pen mate, includes tail-in-
mouth and tail-biting behaviour
Drinking Head on the water nipple
Belly nosing Manipulation of the abdomen of a lying pen mate
Occupation with intervention
material
Head on the additional offered material (in case of tail-
biting outbreaks)
49
2.6.1. Tail lesions and tail losses
The data of tail lesions and tail losses followed a multinomial distribution (Score 0-3).
Therefore, the procedure GLIMMIX was used assuming a cumulative logit link function for
the multinomial distributed data. Due to the fact that tail-biting did not occur during
farrowing, the data for the statistical analysis was limited to the rearing period. The
experimental unit was the pen. The fixed effects group (CG, SG, AG), batch (1-10), week
after weaning (1-6) and the interaction of group and batch were used in the final model for tail
lesions. The pen (nested in batch) was included as a random effect. Only the last observation
at the end of rearing was taken into consideration regarding tail losses. The group (CG, SG,
AG) and the batch (1-10) were used as fixed effects in the final model for tail losses.
2.6.2. Weight gain
In order to estimate the effect of tail-biting on total weight gain during rearing the MIXED
procedure was used. For every treatment group and scoring scheme (tail lesions and tail
losses) nine pens were ranked regarding the total number of piglets with a score higher than
Score 0 within each pen, resulting in three pens for a low, respectively medium and high level
of tail lesions and tail losses (only last observation was taken into consideration). The level of
tail lesions/ tail losses (low, medium, high), the treatment group (CG, SG, AG) and the
interaction between level of tail lesions/ tail losses and treatment group were used as fixed
effects. Significant differences in the least-square-means were adjusted with the Bonferroni-
correction (p < 0.05) (Westfall et al., 2011).
2.6.3. Video analysis
The trait occupation with the raw material provided was investigated with two models
(farrowing, rearing). Occupation was coded as a binary trait (0: not occupied, 1: occupied).
The procedure GLIMMIX was used with the link function logit. The fixed effects group (SG,
AG), batch (1-3), day after first raw material provision (1-16) and the interaction between
group and day after first raw material provision were used in the final model for farrowing.
The fixed effects group (SG, AG), batch (1-3), day after weaning (1-28) and the interaction
between group and day after weaning were used in the final model for rearing. The pen
(nested within batch) was included as a random effect in both models.
50
The trait activity behaviour was analysed with one model. Due to the low frequencies of the
behavioural patterns occupation with raw material and toys, tail exploration, drinking and
belly nosing, they were summarised as “active”, together with sitting, standing and feeding.
Lying behaviour is counted as “inactive” in further analysis. The activity behaviour was
coded as a binary trait, the procedure GLIMMIX was used with the link function logit. The
fixed effects group (CG, SG, AG), batch (1-3), day after weaning (1-28), daytime (6-18h), the
interaction of group and day after weaning, as well as the interaction of batch and day after
weaning were used in the final model. The pen was included as a random effect.
3. Results
3.1. Tail lesions and tail losses
The effect of group, batch, week after weaning and the interaction of group and batch had
highly significant influences on tail lesions (p < 0.001). Tail-biting started on average two to
three weeks after weaning with a tail lesion score higher than 0 in 24.3 % of the piglets in the
third week (Fig. 2) and occurred in all pens.
Figure 2: Estimated frequencies of tail lesions over six weeks after weaning.
100
80
60
40
20
01 2 3 4 5 6
No lesions (0) Small lesions (1)
Moderate lesions (2) Severe lesions (3)
Est
imat
ed f
req
uen
cies
of
tail les
ion
s
Week after weaning
Tail lesions
51
In the fifth week after weaning tail lesions reached a peak (73.7 % of the piglets with scores
higher than 0) and decreased approximately 8.5 % until the last week of rearing. The first tail
losses occurred one to two weeks after the first tail lesions had become visible.
The effect of batch and group had highly significant influences on tail losses at the end of
rearing (p < 0.001). The highest number of tail losses (Score > 0) occurred in batch one
(96.4 %) and batch five (84.4 %), whereas the lowest number of tail losses was documented
in batch nine (9.4 %) and batch ten (7.4 %). Tail losses in other batches ranged from 63 % to
20.9 % (Fig. 3).
Figure 3: Estimated frequencies of tail losses over ten batches at the end of rearing.
At the end of rearing, piglets had lost their tails to the highest extent in CGs (50.4 %),
followed by AGs (49.2 %) and SGs (30.2 %), (Fig. 4).
100
80
60
40
20
01 2 3 4 5 6 7 8 9 10
Original length (0) Loss of tail tip (1)
Partial loss (2) Total loss (3)
Est
imat
ed f
req
uen
cies
of
tail lo
sses
Tail losses
Batch
52
Figure 4: Estimated frequencies of tail losses comparing the treatment groups at the end of
rearing.
3.2. Weight gain
The level of tail lesions and tail losses and the treatment group had no significant influences
on the total weight gain during rearing (p > 0.05). The interaction of the number of tail lesions
and treatment group, as well as the interaction of number of tail losses and treatment group
had significant effects on the total weight gain during rearing (p < 0.05). Piglets in CGs
gained less weight in pens with high levels of tail lesions/ tail losses (LS-Mean ± se: 16.9 ±
1.0 kg/ 15.6 ± 1.0 kg) in comparison to pens with a low level (19.9 ± 1.0 kg / 18.9 ± 1.0 kg).
The total weight gain of piglets in SGs was comparable. Piglets in AGs gained less weight in
medium levels of tail lesions/ tail losses (14.8 ± 1.0 kg) in comparison to pens with low and
high levels (18.5 ± 1.0 kg vs. 16.5 ± 1.0 kg). Differences in total weight gain between the
treatment groups within the levels of tail lesions and tail losses were not significant (p > 0.05).
3.3. Video analysis
Concerning farrowing, the effects of group and batch, as well as the interaction of group and
batch had no significant influences on the occupation with raw material (p > 0.05). The day
after the first raw material provision had a highly significant influence on the number of
100
80
60
40
20
0
Control Alfalfa hay Corn silage
Original length (0) Loss of tail tip (1)
Partial loss (2) Total loss (3)
Tail losses
Est
imat
ed f
req
uen
cies
of
tail lo
sses
53
piglets occupied with the raw material (p < 0.001). No clear trend was visible in the course of
farrowing. During rearing, the group, the day after weaning and the interaction of group and
day after weaning had a significant effect on the occupation with raw material (p < 0.01). The
batch had no significant effect (p > 0.05). Corn silage attracted the piglets’ attention during
the whole observation period, whereas the attractiveness of the alfalfa hay decreased towards
the end of rearing (Fig. 5).
Figure 5: Least-square-means of the occupation with raw material during ten minutes after
provision regarding the interaction of group and day after first raw material
provision in three batches.
The batch, the day after weaning, the daytime, the interaction of group and day after weaning,
as well as the interaction of batch and day after weaning had highly significant influences
(p < 0.001) on the overall activity behaviour during rearing. Group had no significant
influences on the overall activity (p > 0.05). The data showed a two-phase activity curve with
a peak between 10:00-11:00 h and 14:00-15:00 h. The activity of the piglets was highest on
the first day after weaning, as well as between two and three weeks after weaning and
decreased towards the end of rearing (Fig. 6). The activity behaviour between the batches
followed no clear trend during the observation period.
Est
imat
ed p
erce
nta
ge
of
occ
up
ied
an
imal
s
Day after first raw material provision
Farrowing Rearing
54
Figure 6: Least-square-means of the overall activity during rearing regarding the
interaction of group and day after weaning in three batches.
4. Discussion
4.1. Tail lesions and tail losses
No tail-biting was observed in none of the treatment groups during farrowing. This finding is
in line with Munsterhjelm et al. (2009), who did not observe tail lesions either in enriched or
in barren pens in the first four weeks of life. Tail-biting occurred on average in the second
until third week after weaning for the first time, followed by tail losses one until two weeks
later. This finding contributes to the work of Abriel and Jais (2013), who found increasing
tail-biting behaviour in the second week after weaning. An explanation for the beginning of
tail-biting in the early rearing phase could be the number of conversions the piglets are faced
with during the weaning process. When separated from the sow, they need to adapt to a new
environment and feeding, at the same time their immune system is forced to deal with a new
germ environment. Under “natural conditions” weaning is a gradual process in piglets and is
not complete until 10–12 weeks of age (Lallès et al., 2007). Furthermore, the mixing of
piglets and therefore, rank order fights contribute to a stressful situation for weaned piglets
(Hötzel et al., 2011). In intensive housing systems, however, the animals often fail to change
Est
imat
ed p
erce
nta
ge
of
active
anim
als
Day after weaning
55
aversive situations by using evolved coping strategies, and it is argued that abnormal
behaviour can originate from unsuccessful coping behaviour (Wechsler, 1995).
The interaction of group and batch had a highly significant influence on tail lesions.
Nevertheless, there was no clear trend between the treatment groups and the batches. The
variation in the amount of tail lesions supports the assumption that environmental conditions
(e.g. climate, pen structure, group size, feeding spaces, ventilation and health statues) play an
important role in the occurrence of behavioural disorders (Taylor et al., 2012). The group
sizes and the feeding and drinking systems differed between batches in the present study. No
clear connection between group sizes and unit facilities could be drawn for the levels of tail
lesions between the batches. Daily raw material provision seemed to play a subordinated role
in the occurrence of tail lesions, a finding which is not in line with (Zonderland et al., 2008),
who concluded that tail-biting is best prevented with a small amount of straw (20 g/ animal/
day), provided twice daily.
Furthermore, the effect of group and batch had highly significant influences on tail losses at
the end of rearing. The decreasing number of tail losses at the end of the study could be
explained by enhanced and more precise animal observation by stable staff and points out the
learning process in the course of the batches. The staff members reacted faster in case of tail-
biting outbreaks, using tail lesions as an indicator, and offered for example jute sacks or a
straw-peat-mixture to the pigs as additional occupation material. Thus, tail lesions were able
to heal again and did not result in tail losses. In addition to that, the European Food Safety
Authority pointed out good stockman ship and intervention before severe outbreaks become
established as useful (EFSA, 2007). The behavioural disorder occurred to a smaller extent in
SGs, but differences between CGs and AGs were not significant. Curative measurements
were also carried out in CGs to avoid severe injuries and welfare problems in the case of tail-
biting outbreaks. Thus, CGs were falsified, which could have led to an approximation to the
raw material groups. Tail-biting in CGs might have provoked higher numbers of tail losses if
intervention had not been carried out. According to Petersen et al. (1995), pigs from barren
environments had higher frequencies of biting floor and walls, nudging and tail-biting litter
mates than piglets in enriched conditions. Nevertheless, the additional provision of raw
material in piglet bowls in SGs and AGs could not prevent tail-biting in the present study.
56
4.2. Weight gain
The level of tail lesions and tail losses in dependence on the treatment group influenced the
total weight gain of the piglets during rearing. The results of CGs and SGs were in line with
Camerlink et al. (2012), who found that pigs that received more tail-biting, ear-biting and
paw-biting, grew less well (p < 0.05). Moreover, Wallenbeck and Keeling (2013) stated that
tail-biting victims had decreased daily feed intakes during and after the tail-biting outbreaks.
Nevertheless, the results of AGs were in contrast to this and the limited weight data (27 pens)
made it difficult to draw general conclusions.
4.3. Video analysis
Corn silage stayed attractive during the whole observation period. A possible explanation
could be a better palatability of the material due to a higher concentration of carbohydrates
and lower dry-matter content in comparison to alfalfa hay, which contains more fibres. The
preference of pigs for roughage with a low dry-matter content and the attractiveness of
glucose/ sucrose for pigs was shown by Olsen et al. (2000) and Kennedy and Baldwin (1972).
The higher acceptance of corn silage and therefore sustainable occupation could have led to
lower tail losses in SGs in comparison to AGs and CGs at the end of rearing (see Fig. 4). In
the present study, a fresh replacement twice a day should remain the raw material of interest
to the animals because of the novelty aspects (Van de Weerd et al., 2003; Wood-Gush and
Vestergaard, 1991). However, provision in the piglet bowl did not allow every piglet to reach
the raw material at the same time, which could have forced the development of the
behavioural disorder. According to Van de Weerd et al. (2006), the limited size of a point
source may restrict access to enrichment causing competition, aggression or restlessness in
groups of animals. Especially in larger group sizes (> 12 piglets), more than one piglet bowl
should be used for the provision of raw material.
In former studies pig activity has been already identified as a promising tool to predict tail-
biting outbreaks (Statham et al., 2009). The two-phase activity curve during the day
contributes to the findings of Docking et al. (2008) and Zwicker et al. (2012), who found a
synchronisation of feeding and foraging behaviour within a group of pigs. It was notable that
the activity behaviour in all treatment groups increased in the second and third week after
weaning, which could be an indication of the beginning of tail-biting behaviour as described
57
above (see Fig. 2). Nevertheless, the small sample size of piglets analysed during rearing
(n = 188) makes it difficult to transfer results from video observation to the tail-biting
behaviour of the total number of piglets in the present study (n = 723). Furthermore, there was
no clear trend between activity behaviour and the level of tail-biting within the batches. Thus,
the finding of Zonderland et al. (2010b), who connected higher activity behaviour with higher
tail lesions and tail losses, could not be supported in the present study.
5. Conclusion
Additional occupation is recommended and an intensive animal observation is indispensable
to avoid severe tail losses in the rearing of long-tailed pigs. The piglets should be under
precise surveillance especially in the second and third week after weaning. Provision of fresh
material should be applied twice per day during rearing and the type of material should meet
piglets’ demands for foraging behaviour. Further studies should shift the focus from the
victims to the offenders of tail-biting to find out more about individual deficiencies which
lead to the abnormal behaviour (e.g. blood samples, individual video recordings, health
statues).
Conflict of interest
The authors declare that there is no conflict of interest.
Acknowledgements
This work was financially supported by the working group animal welfare of “Rügenwalder
Mühle”.
References
2001/ 93/ EG. Richtlinie 2001/ 93/ EG der Kommission vom 9. November 2001 zur
Änderung der Richtlinie 91/ 630/ EWG über Mindestanforderungen für den Schutz
von Schweinen.
2008/ 120/ EG. Richtlinie des Rates 2008/ 120/ EG vom 18. Dezember 2008 über
Mindestanforderungen für den Schutz von Schweinen.
58
Abriel, M., and C. Jais. 2013. Influence of housing conditions on the appearance of
cannibalism in weaning piglets. Landtechnik 68: 389-393.
Beattie, V. E., N. E. O'Connell, and B. W. Moss. 2000. Influence of environmental
enrichment on the behaviour, performance and meat quality of domestic pigs.
Livestock Production Science 65: 71-79.
Breuer, K. et al. 2003. The effect of breed on the development of adverse social behaviours in
pigs. Applied Animal Behaviour Science 84: 59-74.
Camerlink, I., P. Bijma, B. Kemp, and J. E. Bolhuis. 2012. Relationship between growth rate
and oral manipulation, social nosing, and aggression in finishing pigs. Applied Animal
Behaviour Science 142: 11-17.
Day, J. E. L. et al. 2002. The effects of prior experience of straw and the level of straw
provision on the behaviour of growing pigs. Applied Animal Behaviour Science 76:
189-202.
Day, J. E. L., H. A. Van de Weerd, and S. A. Edwards. 2008. The effect of varying lengths of
straw bedding on the behaviour of growing pigs. Applied Animal Behaviour Science
109: 249-260.
Docking, C. M., H. A. Van de Weerd, J. E. L. Day, and S. A. Edwards. 2008. The influence
of age on the use of potential enrichment objects and synchronisation of behaviour of
pigs. Applied Animal Behaviour Science 110: 244-257.
EFSA. 2007. Scientific report on the risks associated with tail biting in pigs and possible
means to reduce the need for tail docking considering the different housing and
husbandry systems. The EFSA Journal 611: 1-13.
Hötzel, M. J., G. P. P. de Souza, O. A. D. Costa, and L. C. P. Machado Filho. 2011.
Disentangling the effects of weaning stressors on piglets' behaviour and feed intake:
Changing the housing and social environment. Applied Animal Behaviour Science
135: 44-50.
Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 2001. The relationship
between tail biting in pigs, docking procedure and other management practices. The
Veterinary Journal 161: 72-79.
Hurvich, C. M., and C.-L. Tsai. 1989. Regression and time series model selection in small
samples. Biometrika 76: 297-307.
59
Kennedy, J. M., and B. A. Baldwin. 1972. Taste preferences in pigs for nutritive and non-
nutritive sweet solutions. Animal Behaviour 20: 706-718.
Lallès, J.-P., P. Bosi, H. Smidt, and C. R. Stokes. 2007. Weaning - a challenge to gut
physiologists. Livestock Science 108: 82-93.
Moinard, C., M. Mendl, C. J. Nicol, and L. E. Green. 2003. A case control study of on-farm
risk factors for tail biting in pigs. Applied Animal Behaviour Science 81: 333-355.
Munsterhjelm, C. et al. 2009. Experience of moderate bedding affects behaviour of growing
pigs. Applied Animal Behaviour Science 118: 42-53.
Olsen, A. W., E.-M. Vestergaard, and L. Dybkjaer. 2000. Roughage as additional rooting
substrates for pigs. Animal Science 70: 451-456.
Oostindjer, M., H. van den Brand, B. Kemp, and J. E. Bolhuis. 2010. Effects of environmental
enrichment and loose housing of lactating sows on piglet behaviour before and after
weaning. Applied Animal Behaviour Science 134: 31-41.
Petersen, V., H. B. Simonsen, and L. G. Lawson. 1995. The effect of environmental
stimulation on the development of behaviour in pigs. Applied Animal Behaviour
Science 45: 215-224.
SAS. 2008. SAS Institute Inc. Cary, NC, USA.
Schwarz, G. 1978. Estimating the dimension of a model. The annals of statistics 6.2: 461-464.
Sneddon, I. A., V. E. Beattie, N. Walker, and R. N. Weatherup. 2001. Environmental
enrichment of intensive pig housing using spent mushroom compost. Animal Science
72: 35-42.
Statham, P., L. Green, M. Bichard, and M. Mendl. 2009. Predicting tail-biting from behaviour
of pigs prior to outbreaks. Applied Animal Behaviour Science 121: 157-164.
Taylor, N. R., R. M. A. Parker, M. Mendl, S. A. Edwards, and D. C. J. Main. 2012.
Prevalence of risk factors for tail biting on commercial farms and intervention
strategies. The Veterinary Journal 194: 77-83.
Telkänranta, H., K. Swan, H. Hirvonen, and A. Valros. 2014. Chewable materials before
weaning reduce tail biting in growing pigs. Applied Animal Behaviour Science 157:
14-22.
60
TierSchNutztV. 2006. Tierschutz-Nutztierhaltungsverordnung in der Fassung der
Bekanntmachung vom 22. August 2006 (BGBL. I S. 2043), die zuletzt durch Artikel 1
der Verordnung vom 5. Februar 2014 (BGBL. I S. 94) geändert worden ist.
Van de Weerd, H. A., C. M. Docking, J. E. L. Day, P. J. Avery, and S. A. Edwards. 2003. A
systematic approach towards developing environmental enrichment for pigs. Applied
Animal Behaviour Science 84: 101-118.
Van de Weerd, H. A. V. d., C. M. Docking, J. E. L. Day, K. Breuer, and S. A. Edwards. 2006.
Effects of species-relevant environmental enrichment on the behaviour and
productivity of finishing pigs. Applied Animal Behaviour Science 99: 230-247.
Wallenbeck, A., and L. J. Keeling. 2013. Using data from electronic feeders on visit
frequency and feed consumption to indicate tail biting outbreaks in commercial pig
production. Journal of Animal Science 91: 2879-2884.
Wechsler, B. 1995. Coping and coping strategies: A behavioural view. Applied Animal
Behaviour Science 43: 123-134.
Westfall, P. H., R. D. Tobias, and R. D. Wolfinger. 2011. Multiple comparisons and multiple
tests using SAS. SAS Institute.
Wood-Gush, D. G. M., and K. Vestergaard. 1991. The seeking of novelty and its relation to
play. Animal Behaviour 42: 599-606.
Zonderland, J. J., M. B. M. Bracke, L. A. den Hartog, B. Kemp, and H. A. M. Spoolder.
2010a. Gender effects on tail damage development in single- or mixed-sex groups of
weaned piglets. Livestock Science 129: 151-158.
Zonderland, J. J. et al. 2010b. Characteristics of biter and victim piglets apparent before a tail-
biting outbreak. Animal 5: 767-775.
Zonderland, J. J. et al. 2008. Prevention and treatment of tail biting in weaned piglets.
Applied Animal Behaviour Science 110: 269-281.
Zwicker, B., L. Gygax, B. Wechsler, and R. Weber. 2012. Influence of the accessibility of
straw in racks on exploratory behaviour in finishing pigs. Livestock Science 148: 67-
73.
61
CHAPTER TWO
The effect of mixing after weaning on tail-biting during rearing with
characterisation of performers and receivers of manipulative behavioural
patterns
C. Veit1, K. Büttner1, J. Salau1, O. Burfeind2, E. grosse Beilage3, J. Krieter1
1Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Kiel, Germany
2Chamber of Agriculture, Schleswig-Holstein, LVZ Futterkamp, Blekendorf, Germany
3Field Station for Epidemiology, University of Veterinary Medicine, Hannover, Germany
Submitted to Applied Animal Behaviour Science
62
Abstract
The aim of this study was to reveal the effects on tail-biting during rearing of housing
acquainted piglets in comparison to piglets out of mixed litters. The treatment groups “litter-
wise” (LG, n = 240) and “mixed litters” (MG, n = 238) were housed in five identical units
with an additional daily offer of alfalfa hay. Each tail was scored regarding tail lesions/ tail
losses once per week with a four-point score (0 = no damage/ original length to 3 = severe
damage/ total loss). Individual body weights of the piglets at weaning (on average 28 days of
age), at day 16 and at day 40 of rearing were collected. The effect of week after weaning, the
batch and the interaction of treatment group and batch had highly significant influences on tail
lesions (p < 0.001). Tail-biting started in the second week after weaning, with an increasing
development during rearing. First tail losses were observed in the fourth week after weaning.
The batch and the interaction of group and batch had highly significant influences on tail
losses at the end of rearing (p < 0.001). There was no clear trend between the treatment
groups and the batches regarding tail lesions and tail losses. Furthermore, tail-biting did not
affect daily weight gain. To investigate the behaviour of the animals in regard to a tail-biting
outbreak, the piglets of four units were marked individually and observed by video 24 hours
per day. Recorded video material of five pens (60 piglets) was under analysis by
instantaneous scan sampling and continuous observation. Based on the frequencies of the
manipulative behaviour performed, the individual character (CS) of each piglet was defined as
receiver, performer or neutral. The day, the daytime and the pen had highly significant effects
on the frequencies of tail exploration, belly nosing and nosing behaviour (p < 0.001). The
frequencies of tail exploration increased over five days prior to a scored tail-biting outbreak.
The frequencies of belly nosing decreased with increasing distance to weaning. Receivers of
nosing lay significantly more frequently than performers, whereas performers of nosing and
belly nosing stood significantly more frequently than receivers of the respective behaviour
(p < 0.05). The hypothesis of a prevention of tail-biting during rearing through a renunciation
of mixing after weaning could not be confirmed in the present study. It needs to be taken into
account that every piglet has different coping strategies to react to environmental changes and
today’s intensive husbandry may overtax this adaptive ability.
63
1. Introduction
Tail-biting in pigs is a welfare problem with multifactorial causes. Higher stocking densities
and deficiencies in feed quality or accessibility (Moinard et al., 2003), poor ventilation
(Hunter et al., 2001), as well as a lack of rooting substrate (Zonderland et al., 2008) have been
identified as environmental risk factors. On the biological side, poor health (Day et al., 2002),
breed (Breuer et al., 2003) and gender (Zonderland et al., 2010a) could also play a role.
Former studies have pointed out a concentration of abnormal behaviour during the early
rearing phase in long-tailed piglets (Abriel and Jais, 2013). This assessment should direct the
focus on the challenges piglets are faced with through the weaning process. Besides the
change in environment and diet, as well as the separation from the sow, the mixing of
unfamiliar litters is one of the possible stressors during weaning in commercial farming
systems (D'Eath, 2005). Due to management practices piglets are often sorted by gender and
size and rehoused in rearing pens. Confrontation with unfamiliar pen mates leads to rank
order fights in the first days after weaning and regrouping. According to Hötzel et al. (2011),
the mixing of litters implicates higher frequencies of agonistic and exploratory behaviours,
lower resting frequencies and a higher proportion of severe skin lesions in comparison to
unmixed litters. In addition, Fraser et al. (1974) pointed out that familiarity, in the sense of
prior exposure to a stranger, reduces aggression. Piglets which are socialised prior to weaning
formed a new stable dominance hierarchy more quickly when mixed again after weaning
(D'Eath, 2005). Furthermore, familiarising piglets from different litters reduces social stress at
weaning and increased weight gain afterwards (Kutzer et al., 2009). Environmental factors
which disturb the normal hierarchy can result in frustration and aggression (Schrøder-Petersen
and Simonsen, 2001). This may, in turn, increase the risk of tail-biting. Pigs in group-
farrowing systems are more tolerant of unfamiliar pigs when mixed, compared to pigs reared
in confinement systems (Li and Wang, 2011). Bohnenkamp et al. (2012) stated that the early
mixing of unacquainted litters during lactation reduces agonistic behaviour and lesion score
difference during the first two days after weaning. Although the effects on tail-biting of social
status and events such as mixing have received limited attention, mixing may act in triggering
tail-biting under commercial conditions (EFSA, 2007). Based on these results, the hypothesis
was proposed that the avoidance of stress through mixing after weaning has positive effects
64
on the manifestation of behavioural disorders. Therefore, litter-wise and mixed-housed piglets
were compared regarding tail lesions and tail losses during rearing.
Moreover, detailed information on piglet behaviour at an individual level is still insufficient.
Hessing et al. (1993) found the existence of behavioural strategies in piglets to cope with
conflict situations. Koolhaas et al. (1999) concluded that there are distinct phenotypes
(proactive and reactive coping styles) which are more or less stable over time in their
response to stressors and, thus, may adapt differentially to environmental conditions. Thus, a
further aim of the present study was the investigation of the performers and receivers of
manipulative behavioural patterns (tail exploration, belly nosing and nosing). The focus was
on video observations of five days prior and the day of a tail-biting outbreak itself.
2. Materials and methods
2.1. Animals and housing
Data collection was carried out on the research farm of the Chamber of Agriculture of
Schleswig-Holstein (Futterkamp), Germany, between February and April 2014. In the study,
478 crossbreed piglets (Pietrain x (Large White x Landrace)) from 40 litters were used in five
batches and kept under conventional farming practices. Tails were not docked and males were
not castrated. The piglets were weaned on average at 28 days with an average weaning weight
of 8.3 ± 1.6 kg. Five identical rearing units consisting of eight pens each were consecutively
used. Rearing lasted for 40 days in mixed-gender groups until an average weight of
25.9 ± 3.8 kg. The groups consisted of 12 piglets per pen with a space allowance of 0.38 m²/
animal. The used feeding system was mash feed ad libitum with an animal to feeding place
ratio of 2:1 and a diet composition of 17.0 % protein, 1.3 % lysine, 0.7 % calcium and 0.25 %
sodium (13.4 MJ ME). Water was accessible through nipple drinkers. The plastic floor was
fully slatted and no bedding material was provided. One plastic ball per pen (suspended on a
metal chain) and alfalfa hay in plastic bowls (one per pen, Ø 40 cm, animal to occupation
place ratio 1.2:1) was provided as environmental enrichment material once per day. The
environmental temperature was automatically regulated by forced ventilation. It was set at
28.0 °C on day one of rearing and decreased stepwise until 24.0 °C on day 40. The animals
had full artificial lighting between 06:00 h and 19:00 h. Pigs in the present study were kept in
65
consideration of the European Directive (2008/ 120/ EG) and in accordance with the
Tierschutz-Nutztierhaltungsverordnung (TierSchNutztV, 2006).
2.2. Experimental design
In total 478 piglets were divided randomly into two groups, 240 piglets (♂ 124, ♀ 116) were
housed in litter-consisting groups (LG), whereas 238 piglets (♂ 117, ♀ 121) were mixed out
of at least three different litters (MG). Each unit consisted of four pens with LGs and four
pens with MGs, resulting in 20 pens for each treatment. The locations of the treatment groups
within the units were randomised.
2.3. Data collection
2.3.1 Scoring
Scoring of tail lesions and tail losses was carried out weekly. The scoring scheme (modified
from Abriel, Jais, 2013) classified the severity of tail lesions with a four-point score consisting
of “no visible damage“ (0), “scratches, light bite marks” (1), “moderate damage” (2) and
“severe damage” (3). A tail-biting outbreak was defined as a point in time, when at least one
piglet showed a freshly bleeding tail wound or a loss of the tail. Tail losses were classified by
“original length of tail” (0), “loss of tail tip” (1), “partial loss” (2) and “total loss or necrosis”
(3). Furthermore, the gender and the size of the animals (small, medium, large, in relation to
pen mates) were recorded during the scoring process.
2.3.2 Body weight
Individual body weights of the piglets at weaning, at day 16 and at day 40 of rearing were
collected.
2.3.3 Video surveillance
In total 32 pens (four units) were equipped with colour cameras and recorded 24 hours per
day (Santec, VTC-249/ IRP/ W or VTC-279/ IRPWD). The piglets were individually marked
with colour spray three times per week. The open source software BORIS (Friard, 2014) was
used for the video analysis of five pens (three MGs, two LGs). In total 60 piglets (♂ 29, ♀ 31)
66
were analysed five days prior to a scored tail-biting outbreak and the day of an outbreak itself.
Eleven different behavioural patterns were coded. The ethogram is given in Table 1.
Table 1: Ethogram used for video observation.
Behavioural pattern Description
Instantaneous scan sampling
Lying Lying on the side or ventrally
Standing Body supported by four stretched legs, includes
locomotion
Feeding Head positioned in the feeder
Occupation with raw material Sniffing, nosing or rooting the raw material in piglet bowl
Pen investigation Head on the pen surrounding (floor and walls)
Continuously collected
Tail exploration
Performer Head on the tail of a pen mate, includes tail-in-mouth and
tail-biting behaviour
Receiver Being manipulated by a pen mate on the tail, includes
tail-in-mouth and tail-biting behaviour
Belly nosing
Performer Manipulation of the abdomen of a lying pen mate
Receiver Being manipulated by a pen mate on the abdomen, while
lying
Nosing
Performer Snout contact with any part of the body of a pen mate
except the belly region
Receiver Being contacted by snout on any part of the body, except
the belly region
67
Time budgets of each animal were investigated by instantaneous scan sampling over 20
minutes from every second hour between 06:00 h and 18:00 h (06:00 h to 06:20 h, 08:00 h to
08:20 h, 10:00 h to 10:20 h, 12:00 h to 12:20 h, 14:00 h to 14:20 h, 16:00 h to 16:20 h and
18:00 h to 18:20 h), the sampling scheme was every 2 minutes. Every 20 min interval is
counted as a scan, resulting in 42 scans per pen over six days, respectively 210 scans in total.
Due to technical difficulties, there was a lack of 17 scans, thus, the data was limited to 193
scans. Additionally, the manipulative behavioural patterns tail exploration (te), belly nosing
(bn) and nosing (no) were recorded continuously over the above-mentioned time frame
determining the receivers (R) and performers (P) of each behaviour. In order to make the
piglets’ behaviour comparable and classifiable, the frequencies of the recorded manipulative
behavioural patterns required a conversion into scores/ indices. The character score (CS) was
developed to assign a number to each piglet (i), defining it as receiver or performer by
changing the algebraic sign. The following formula defines CS, where x ∈{te, bn, no}, y ∈
{1, 2, 3, 4, 5} and i ∈ {1,…,60}:
CSx,y (i) = [Px(i)/ max_Px,y] - [Rx(i)/ max_Rx,y] (1)
Px(i) is the number of manipulative contacts as performer of behaviour x for piglet i and
max_Px,y is the maximum number of manipulative contacts as performer in pen y. Rx(i) is the
number of manipulative contacts as receiver of behaviour x for piglet i and max_Rx,y is the
maximum number of manipulative contacts as receiver in pen y. CS ranges between -1
(absolute receiver) and +1 (absolute performer);
In order to determine the ranges (upper limit (UL) and lower limit (LL)) of CS to assign
piglets to different character categories, the following formulas were used:
ULx,y = MWx,y + 0.52 x std x,y (2)
LLx,y = MWx,y – 0.52 x std x,y (3)
MWx,y denote the mean and std x,y denote the standard deviation of CS x,y. The constant 0.52 is
the 70 %-quantile of the standard normal distribution. Piglets with CSs within the range of UL
and LL were designated “neutral”. Piglets with a CS which exceeded the UL were named
“performer” and piglets with a CS below the LL were named “receiver”.
68
2.4. Statistical analysis
The software package SAS 9.2® was used for statistical analysis (SAS, 2008). The fit
statistics AICC “Akaike’s information criterion corrected” (Hurvich and Tsai, 1989) and the
BIC “Bayesian information criterion” (Schwarz, 1978) were used to evaluate the fitting of the
models. The fixed effects were added stepwise to the models. The model with the smallest
AICC and BIC was chosen for the analysis.
2.4.1. Tail lesions and tail losses
The data of tail lesions and tail losses followed a multinomial distribution (Scores 0-3). Thus,
the GLIMMIX procedure was used assuming a cumulative logit link function for the
multinomial distributed data. The fixed effects treatment group (LG, MG), week after
weaning (1-6), batch (1-5) and the interaction of treatment group and batch were added
stepwise and used as fixed effects in the final model for tail lesions. The piglet was included
as a random effect and was nested within group and batch. The database was limited to the
last observation at the end of rearing regarding tail losses. The fixed effects group (LG, MG)
and batch (1-5) and the interaction of group and batch were used as fixed effects in the final
model for tail losses.
2.4.2. Weight data
In order to estimate the effect of tail-biting on daily weight gain, the MIXED procedure was
used. Daily weight gain of three time periods was analysed: weaning to day 16 (period 1), day
16 to day 40 (period 2) and weaning to day 40 (period 3). The scores of tail lesions on day 16
and day 40, as well as the scores of tail losses on day 40 of rearing were classified by
distribution: class 0 (0), class 1 (1) and class 2 (2, 3) for tail lesions, as well as class 0 (0) and
class 1 (1, 2, 3) for tail losses. Low frequencies of tail losses in the study did not allow the
distinction into three classes, which may confound the gradations. Classes of tail lesions (0, 1,
2) on day 16 were added as fixed effects to the model for period 1, whereas classes of tail
lesions and tail losses on day 40 were added as fixed effects to the model for period 2 and
period 3. Period 1 was not analysed for tail losses, because they were not observed until four
weeks after weaning. The treatment group (MG, LG), the batch (1-5), the interaction of group
and batch and the gender were used as fixed effects in all models. Weaning weight was added
69
as a covariable to the final models. Significant differences in the least-square-means were
adjusted with the Bonferroni-correction (p < 0.05) (Westfall et al., 2011).
2.4.3. Video analysis
Video data was limited to five pens, since continuous observation of manipulative
behavioural patterns required a high time effort due to the assignment of performer and
receiver of each interaction. Therefore, the treatment groups (LGs, MGs) were not considered
in further statistical analysis.
The count data of the continuously observed manipulative behavioural patterns was analysed
using the GLIMMIX procedure with a Poisson-distribution. The fixed effects day (- 5, - 4, - 3,
- 2, - 1, 0), daytime (6, 8, 10, 12, 14, 16, 18) and pen (1-5) were used in the models for tail
exploration, belly nosing and nosing. The piglet (nested within pen) was added as a random
effect to the final models.
The accumulated frequencies of the behaviours lying, standing and feeding, which were
observed by instantaneous scan sampling of each piglet over six days (every 20 min of every
second hour from 06:00 h to 18:00 h), were analysed using the MIXED procedure. The
behaviours pen investigation and occupation with provided material were rarely shown by the
piglets, thus, not considered in further statistical analysis. Three different models were used to
test the effect of character (calculated by formulas 1 to 3) separately for tail exploration, belly
nosing and nosing. The character of the piglets (performer, neutral, receiver) for the respective
manipulative behavioural pattern and the pen (1-5) were used as fixed effects in the models
for lying, standing and feeding behaviour. Daily weight gain was added as a covariable to the
final models. The gender was removed from the models due to low improvements in the
fitting and no significant impact. Significant differences in the least-square-means were
adjusted with the Bonferroni-correction (p < 0.05) (Westfall et al., 2011).
3. Results
3.1. Tail lesions and tail losses
The effect of week after weaning, the batch and the interaction of group and batch had highly
significant influences on tail lesions (p < 0.001). The group had no significant effect
(p > 0.05). Tail-biting started on average in the second week after weaning with a tail lesion
70
score higher than 0 in 15.8 % of the piglets and increased towards the end of rearing (90.8 %
of the piglets with a score higher than 0) (Fig. 1). The first tail losses were observed on
average in the fourth week after weaning.
Figure 1: Estimated frequencies of tail lesions over six weeks after weaning.
The piglets in batch five had the highest number of tail lesions in both treatment groups (Fig.
2a and 2b).
100
80
60
40
20
0
1 2 3 4 5 6
No lesions (0) Small lesions (1)
Moderate lesions (2) Severe lesions (3)
Est
imat
ed f
req
uen
cies
of
tail les
ion
s
Week after weaning
Tail lesions
71
Figure 2: Estimated frequencies of tail lesions over all batches in LGs (a) and MGs (b) .
The batch and the interaction of group and batch had highly significant influences on tail
losses at the end of rearing (p < 0.001). The group had no significant effect (p > 0.05). The
highest number of tail losses (Score > 0) occurred in LGs in batch three (65.4 %, Fig. 3a),
whereas in MGs the highest number of tail losses was documented in batch four
100
80
60
40
20
0
1 2 3 4 5
Figure 2a
Est
imat
ed f
req
uen
cies
of
tail les
ion
s
Batch
100
80
60
40
20
0
1 2 3 4 5
No lesions (0)
Figure 2b
Moderate lesions (2) Severe lesions (3)
Est
imat
ed f
req
uen
cies
of
tail les
ion
s
Batch
Tail lesions
Small lesions (1)
72
(81.4 %, Fig. 3b). Tail losses in other batches ranged from 18.8 % to 37.3 % in LGs, as well
as from 10.2 % to 27.6 % in MGs.
Figure 3: Estimated frequencies of tail losses over all batches, regarding the last week of
rearing, in LGs (a) and MGs (b).
100
80
60
40
20
0
1 2 3 4 5
Figure 3a
Est
imat
ed f
req
uen
cies
of
tail lo
sses
Batch
100
80
60
40
20
0
1 2 3 4 5
(1)
(3)
Figure 3b
Partial loss (2) Total loss/ necrosis
Est
imat
ed f
req
uen
cies
of
tail lo
sses
Batch
Tail losses
Original length (0) Loss of tail tip
73
3.2. Weight gain
The treatment group, the batch and the interaction of treatment group and batch had
significant influences on daily weight gain in all analysed periods (p < 0.01). Moreover, the
classes of tail lesions at day 40 had significant influences on daily weight gain in the
respective analysed periods (p < 0.05). The classes of tail lesions at day 16, the classes of tail
losses at day 40 and the gender had no significant effect on daily weight gain in the respective
analysed periods (p > 0.05). The least-square-means of daily weight gain regarding the effect
of different classes of tail lesions and tail losses in different time periods are given in Table 2.
The daily weight gain showed no clear trend over treatment groups and batches and could not
be connected with the weekly scoring of tail lesions (Fig. 2) and tail losses (Fig. 3).
Table 2: Least-square-means (LSM) and standard error (SE) of daily weight gain (g) in
three different time periods regarding the effect of different classes of tail lesions
and tail losses.
Period 1 (d1 - d16)
LSM ± SE
Period 2 (d16 - d40)
LSM ± SE
Period 3 (d1 - d40)
LSM ± SE
Tail lesions
Class 0 184.6 ± 4.15 534.0a ± 21.5 391.3a ± 15.3
Class 1 207.9 ± 10.7 594.4ᵇ ± 11.2 425.3a ± 7.97
Class 2 195.4 ± 9.54 617.5ᵇ ± 6.66 450.8b ± 4.74
Tail losses
Class 0 607.5 ± 6.36 441.7 ± 4.55
Class 1 598.9 ± 13.8 434.7 ± 9.88
a-b Values with different superscripts differ significantly (p < 0.05).
3.3. Video analysis
An overview of the frequencies of manipulative behaviour performed/ received per pig and
the average CS over all pens is given in Table 3.
74
Table 3: Mean, standard deviation (std), minimum (min) and maximum (max) of the
frequencies of manipulative behaviour performed/ received per pig and of the
character score (CS) of the respective behaviour.
Behaviour
n_performed/ received per pig CS
Mean ± std Min Max Mean ± std Min Max
Tail exploration 17.9 ± 9.70 1.0 43.0 -0.06 ± 0.35 -0.95 0.74
Belly nosing 20.3 ± 26.6 1.0 157 -0.10 ± 0.39 -0.93 0.95
Nosing 45.5 ± 29.2 1.0 146 -0.09 ± 0.36 -0.80 0.63
The day, the daytime and the pen had highly significant effects on the frequencies of tail
exploration, belly nosing and nosing performed (p < 0.001). The frequencies of tail
exploration performed increased towards the day of a scored tail-biting outbreak (LS-Means
of the day -5 differed significantly from the days -3, -2, -1, 0, p < 0.05, Fig. 4); whereas the
frequencies of belly nosing decreased (LS-Means of the days -5 to -1 differed significantly
from day 0, p < 0.05, Fig. 4). The frequencies of nosing reached its maximum on day -3 and
day -1 (Fig. 4).
75
Figure 4: Least-square-means of the frequencies of manipulative behaviour performed
on five days prior to a scored tail-biting outbreak and the day of an outbreak
itself.
In the daily course, the frequencies of manipulative behavioural patterns performed followed
the diurnal activity curve of the piglets and reached a maximum at 10:00 h and 16:00 h
(Fig. 5). The frequencies of belly nosing were highest in the pen which was observed most
closely (two weeks) to weaning (LS-Mean ± se: 0.73 ± 0.19 per piglet and scan) and
decreased with increasing distance to weaning (pens observed four weeks after weaning:
0.2 ± 0.05 to 0.41 ± 0.1; five weeks after weaning: 0.08 ± 0.02 to 0.19 ± 0.05, respectively).
76
Figure 5: Least-square-means of the frequencies of manipulative behaviour performed
during the day (06:00h to 18:00h).
The classified character of the piglets for nosing behaviour and the pen had significant
influences on the accumulated frequencies of lying (p < 0.05). The character of the piglets for
tail exploration and belly nosing behaviour had no significant effect on the frequencies of
lying (p > 0.05). The receivers of nosing lay significantly more frequently than the performers
(LS-Mean ± se: 276.3 ± 4.9 vs. 249.4 ± 5.1, p < 0.001). The character of the piglets for tail
exploration, belly nosing and nosing, as well as the pen had significant effects on the
frequencies of standing (p < 0.05). Performers of nosing and belly nosing stood significantly
more frequently than receivers of the respective behaviour (86.9 ± 3.6 vs. 61.5 ± 3.4,
respectively 89.0 ± 4.2 vs. 64.9 ± 3.8, p < 0.01). Performers of tail exploration tended to stand
more frequently than the receivers (84.3 ± 4.3 vs. 70.4 ± 4.0, p = 0.07).
4. Discussion
4.1. Tail lesions and tail losses
Tail-biting occurred on average in the second week after weaning for the first time, followed
by tail losses two weeks later. This is in line with Abriel and Jais (2013), who found
77
increasing tail-biting behaviour in the second week after weaning. Early weaning, which
under natural conditions is a gradual process that lasts until 10–12 weeks of age (Lallès et al.,
2007), is a challenging situation for the piglets and could trigger the stress-induced
behavioural disorder (Sinisalo et al., 2012). Animals are likely to develop abnormal behaviour
under housing conditions in which they fail to cope with aversive situations by performing
normal behaviour (Wechsler, 1995).
There was no clear trend between the treatment groups and the batches regarding tail lesions
and tail losses, except for high numbers of tail lesions in batch five in LGs and MGs. A
difference in treatment between the batches was the individual marking of the piglets in
batches one to four due to video observation. The piglets were treated three times per week
and therefore occupied for the time of colour application, which lasted about one to two hours
per unit. Moreover, the colour on the back of pen mates attracted the attention of the piglets
for a certain amount of time after treatment. Certainly, the individual marking was a stressful
measurement for the piglets but transient, not regularly repeated, short stress may not really
affect welfare but rather may be a suitable way to overcome boredom (Manteuffel, 2002). If
colour application is counted as environmental enrichment, it could be an explanation as to
why the number of tail lesions was lower in batches one to four in comparison to batch five.
The results of tail lesion scoring could imply that the highest number of tail losses occurred
subsequently in batch five. In contrast, the highest number of tail losses at the end of rearing
was noted for LGs in batch three and for MGs in batch four. These findings could be
explained by the different forms of tail-biting described by Taylor et al. (2010). In the case of
“two stage tail-biting”, a pre damage stage, which is characterized by tail-in-mouth behaviour,
turns after a while into a damage stage when first tail wounds are visible. This form of tail-
biting was easy to document by weekly scoring, because the process lasted for days. In the
case of “sudden forceful tail-biting”, the piglets’ tails were amputated partly by other piglets
within a short period of time, thus, not subsequently evaluated in high levels of tail lesions,
since wounds could heal more quickly.
Another attempt to explain the differences in tail lesions and tail losses between the batches
could be facility problems within the units. Even if the units were identical in construction,
provided the same feeding system, as well as the same pen sizes and structure, dysfunctions in
water or feed accessibility or climate variations, respectively, could have provoked
78
behavioural disorder. Taylor et al. (2012) determined the categories climate and environment
(temperature, humidity, draughts, aversive atmospheric factors) to be the highest risk factors
for tail-biting by using a husbandry advisory tool. Moreover, Hunter et al. (2001) showed that
insufficient accessibility to feed increased the risk of tail-biting.
4.2. Weight gain
The daily weight gain of piglets in high classes of tail lesions was significantly higher than in
low classes of tail lesions. Thus, the assumption that piglets which suffered from tail-biting
would gain less weight subsequently could not be supported by the results of the present
study. This is not in line with Camerlink et al.(2012), who found that pigs that received more
tail-biting, ear-biting and paw-biting grew significantly less well. An explanation as to why
tail-biting did not affect the daily weight gain in the present study could be the low average
number of severe tail lesions in the course of rearing, resulting in a low average level of tail
losses at the end of rearing. Moreover, heavier piglets seemed to be bitten more than lighter
piglets; they were probably less active (lay more frequently) and, thus, an easier aim for tail-
biters. This contributes to the work of Zonderland et al. (2010b), who found victims were the
heavier pigs in the pen.
4.3. Video analysis
The increasing frequencies of tail exploration prior to a tail-biting outbreak confirmed the
findings of Zonderland et al. (2010, 2011). Here, restlessness increased and the frequency of
performed tail bites tended to increase in the six days preceding a tail-biting outbreak. It needs
to be taken into account that the determined behaviour tail exploration included tail-in-mouth
behaviour (Tab. 1), which is described as a part of the “pre damage stage” in the development
of tail-biting (Taylor et al., 2010). In the weekly scoring of tail lesions, a tail-biting outbreak
was not scored until the so-called “damage stage” of behavioural disorder had occurred.
The frequencies of belly nosing were highest in the pen which was observed most closely to
weaning, which indicates a connection to the weaning process. According to Mason (1991),
belly nosing could be classified as a stereotype since it is repetitive and appears to have no
obvious function. Additionally, Gardner et al. (2001) stated that belly nosing does not appear
79
to be a general behavioural indicator of stress. It seems to be more a redirected suckling
behaviour due to early weaning (Widowski et al., 2008).
During video analysis, every piglet was assigned as receiver or performer of manipulative
behaviour in an observed interaction. Since every piglet was able to receive and perform the
respective behaviour simultaneously in the observed period, a clear distinction was not
possible. With formulas 1 to 3 the character of every piglet regarding the respective
manipulative behaviour was classified as performer, receiver or neutral in order to make them
comparable. The receivers of nosing behaviour lay significantly more frequently than the
performers, whereas the performers of nosing and belly nosing stood significantly more
frequently. Thus, receivers reacted less defensively and tolerated manipulation with the snout
more frequently, whereas performers showed higher general activity. Considering the
background of the controversially discussed behaviours, it needs to be taken into account that
nosing is a form of social contact and should not necessarily be counted as negative
behaviour. Nevertheless, Beattie et al. (2005) stated that tail-biting is linked to ear-biting and
nosing in the genital or belly region, respectively. Furthermore, it needs to be taken into
account that the CS were calculated from video data of only six days of rearing in the present
study and there were already indications that the individual character is not stable over time
(Stukenborg et al., 2012).
5. Conclusion
Stress due to regrouping after weaning may contribute to the occurrence of tail-biting as an
additional effect to other risk factors. However, in the present study, a renunciation of mixing
after weaning did not prevent tail-biting behaviour during rearing. There were differences in
individual pig characters and it needs to be taken into account that every piglet has different
coping strategies to react to environmental changes. Today’s conventional husbandry systems
could overtax this adaptive capacity of the piglets. Therefore, housing should be adapted
further in a way which meets the demands of natural behaviour in pigs.
Acknowledgments
This project was kindly financed by the Ministry of Energy, Agriculture, the Environment and
Rural Areas, Schleswig-Holstein.
80
References
2008/ 120/ EG. Richtlinie des Rates 2008/ 120/ EG vom 18. Dezember 2008 über
Mindestanforderungen für den Schutz von Schweinen.
Abriel, M., and C. Jais. 2013. Influence of housing conditions on the appearance of
cannibalism in weaning piglets. Landtechnik 68: 389-393.
Beattie, V. E. et al. 2005. Factors identifying pigs predisposed to tail biting. Animal Science
80: 307-312.
Bohnenkamp, A. L., I. Traulsen, C. Meyer, K. Müller, and J. Krieter. 2012. Comparison of
growth performance and agonistic interaction in weaned piglets of different weight
classes from farrowing systems with group or single housing. Animal 7: 309-315.
Breuer, K. et al. 2003. The effect of breed on the development of adverse social behaviours in
pigs. Applied Animal Behaviour Science 84: 59-74.
Camerlink, I., P. Bijma, B. Kemp, and J. E. Bolhuis. 2012. Relationship between growth rate
and oral manipulation, social nosing, and aggression in finishing pigs. Applied Animal
Behaviour Science 142: 11-17.
D'Eath, R. B. 2005. Socialising piglets before weaning improves social hierarchy formation
when pigs are mixed post-weaning. Applied Animal Behaviour Science 93: 199-211.
Day, J. E. L. et al. 2002. The effects of prior experience of straw and the level of straw
provision on the behaviour of growing pigs. Applied Animal Behaviour Science 76:
189-202.
EFSA. 2007. Scientific report on the risks associated with tail biting in pigs and possible
means to reduce the need for tail docking considering the different housing and
husbandry systems. The EFSA Journal 611: 1-13.
Fraser, D. 1974. The behaviour of growing pigs during experimental social encounters. The
Journal of Agricultural Science 82: 147-163.
Friard, O. 2014. Behavioral observation research interactive software.
http://penelope.unito.it/boris/.
Gardner, J. M., I. J. H. Duncan, and T. M. Widowski. 2001. Effects of social 'stressors' on
belly-nosing behaviour in early-weaned piglets: Is belly-nosing an indicator of stress?
Applied Animal Behaviour Science 74: 135-152.
81
Hessing, M. J. C. et al. 1993. Individual behavioural characteristics in pigs. Applied Animal
Behaviour Science 37: 285-295.
Hötzel, M. J., G. P. P. de Souza, O. A. D. Costa, and L. C. P. Machado Filho. 2011.
Disentangling the effects of weaning stressors on piglets' behaviour and feed intake:
Changing the housing and social environment. Applied Animal Behaviour Science
135: 44-50.
Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 2001. The relationship
between tail biting in pigs, docking procedure and other management practices. The
Veterinary Journal 161: 72-79.
Hurvich, C. M., and C.-L. Tsai. 1989. Regression and time series model selection in small
samples. Biometrika 76: 297-307.
Koolhaas, J. M. et al. 1999. Coping styles in animals: Current status in behavior and stress-
physiology. Neuroscience & Biobehavioral Reviews 23: 925-935.
Kutzer, T., B. Bünger, J. B. Kjaer, and L. Schrader. 2009. Effects of early contact between
non-littermate piglets and of the complexity of farrowing conditions on social
behaviour and weight gain. Applied Animal Behaviour Science 121: 16-24.
Lallès, J.-P., P. Bosi, H. Smidt, and C. R. Stokes. 2007. Weaning - a challenge to gut
physiologists. Livestock Science 108: 82-93.
Li, Y., and L. Wang. 2011. Effects of previous housing system on agonistic behaviors of
growing pigs at mixing. Applied Animal Behaviour Science 132: 20-26.
Manteuffel, G. 2002. Central nervous regulation of the hypothalamic-pituitary-adrenal axis
and its impact on fertility, immunity, metabolism and animal welfare-a review. Archiv
für Tierzucht 45: 575-595.
Mason, G. J. 1991. Stereotypies: A critical review. Animal Behaviour 41: 1015-1037.
Moinard, C., M. Mendl, C. J. Nicol, and L. E. Green. 2003. A case control study of on-farm
risk factors for tail biting in pigs. Applied Animal Behaviour Science 81: 333-355.
SAS. 2008. SAS Institute Inc. Cary, NC, USA.
Schrøder-Petersen, D. L., and H. B. Simonsen. 2001. Tail biting in pigs. The Veterinary
Journal 162: 196-210.
Schwarz, G. 1978. Estimating the dimension of a model. The annals of statistics 6.2: 461-464.
82
Sinisalo, A., J. K. Niemi, M. Heinonen, and A. Valros. 2012. Tail biting and production
performance in fattening pigs. Livestock Science 143: 220-225.
Stukenborg, A. et al. 2012. Heritabilities of agonistic behavioural traits in pigs and their
relationships within and between different age groups. Livestock Science 149: 25-32.
Taylor, N. R., D. C. J. Main, M. Mendl, and S. A. Edwards. 2010. Tail-biting: A new
perspective. The Veterinary Journal 186: 137-147.
Taylor, N. R., R. M. A. Parker, M. Mendl, S. A. Edwards, and D. C. J. Main. 2012.
Prevalence of risk factors for tail biting on commercial farms and intervention
strategies. The Veterinary Journal 194: 77-83.
TierSchNutztV. 2006. Tierschutz-Nutztierhaltungsverordnung in der Fassung der
Bekanntmachung vom 22. August 2006 (BGBL. I s. 2043), die zuletzt durch Artikel 1
der Verordnung vom 5. Februar 2014 (BGBL. I s. 94) geändert worden ist.
Wechsler, B. 1995. Coping and coping strategies: A behavioural view. Applied Animal
Behaviour Science 43: 123-134.
Westfall, P. H., R. D. Tobias, and R. D. Wolfinger. 2011. Multiple comparisons and multiple
tests using SAS. SAS Institute.
Widowski, T. M., S. Torrey, C. J. Bench, and H. W. Gonyou. 2008. Development of ingestive
behaviour and the relationship to belly nosing in early-weaned piglets. Applied
Animal Behaviour Science 110: 109-127.
Zonderland, J. J., M. B. M. Bracke, L. A. den Hartog, B. Kemp, and H. A. M. Spoolder.
2010a. Gender effects on tail damage development in single- or mixed-sex groups of
weaned piglets. Livestock Science 129: 151-158.
Zonderland, J. J., B. Kemp, M. B. M. Bracke, L. A. den Hartog, and H. A. M. Spoolder. 2011.
Individual piglets' contribution to the development of tail biting. Animal 5: 601-607.
Zonderland, J. J. et al. 2010b. Characteristics of biter and victim piglets apparent before a tail-
biting outbreak. Animal 5: 767-775.
Zonderland, J. J. et al. 2008. Prevention and treatment of tail biting in weaned piglets.
Applied Animal Behaviour Science 110: 269-281.
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GENERAL DISCUSSION
Working hypotheses
The aim of the present thesis was the evaluation of tail-biting behaviour in pigs in order to
gain further information on the causes and the underlying mechanism of this abnormal
behaviour. Therefore, two different experimental set-ups concerning environmental
enrichment and weaning management were carried out under practical conditions. In the first
study, the focus was on the effect of manipulable material provided to piglets. In contrast to
former studies in this research field, the focus was on the farrowing and rearing phase instead
of the fattening period. The assumption was made that a daily provision of raw material from
the second week of life until the end of rearing could help to prevent tail-biting behaviour in
pigs. In the second study, the concern was weaning management since reliable information on
optimal weaning management and its effects is still insufficient. The hypothesis was proposed
that the rearing of siblings and, thus, a renunciation of mixing after weaning can prevent tail-
biting during rearing. The data in both studies were collected with a scoring scheme taking
into consideration both tail lesions and tail losses. Additionally, video observations in the
environmental enrichment study delivered data on the activity behaviour of the piglets at
group level and occupation with the material provided. The focus of the video analysis in the
weaning management study was on manipulative behavioural patterns and the piglets’
behaviour prior to a tail-biting outbreak, thereby providing further information on character
differences at individual level.
Raw material
Nowadays, animal welfare receives more public attention and is widely discussed on farms.
The five freedoms of animal welfare declared by the UK Farm Animal Welfare Council
(FAWC, 1979) are the freedom from hunger and thirst, from discomfort, from pain, injury
and disease, from fear and distress and the freedom to express normal behaviour. Especially
the last point is important regarding the development of behavioural disorders, because barren
environments of intensive housing systems do often not meet the natural demands of the
animals. If the aversive situation for the piglets consists of the absence of a stimulus to release
a specific behaviour (e.g. rooting), exploratory behaviour is the adaptive coping response
84
(Wechsler, 1995). Unsatisfied foraging behaviour could lead to more manipulation of the tail
of a pen mate, resulting in tail wounds as described by Taylor et al. (2010). The results of
Douglas et al. (2012) show that pigs have more optimistic judgement biases in enriched
environments indicative of a more positive affective state. Also, pigs that have spent time in
an enriched environment react more negatively to being subsequently housed in a barren
environment. Several aspects of a realisation of environmental enrichment in intensive
husbandry are discussed below.
A problem in the environmental enrichment study was that in pens housing 24 piglets (two
litters combined) one piglet bowl resulted in a piglet to occupation ratio of 2.4:1, which
implied that not every piglet reached the provided material at the same time. The limited size
of a point source may restrict access to enrichment causing competition, aggression or
restlessness in groups of animals (Van de Weerd et al., 2006). Pigs’ feeding behaviour
follows a synchronic pattern, a reason why a ratio which exceeds 1:1 is unfavourable. Hansen
et al. (1982) showed a clear connection between the frequencies of aggression, tail- and ear-
biting comparing piglets with access to one feeder in comparison to several feeders.
Nevertheless, there were no significant differences regarding tail-biting in the raw material
groups between the pens housing 24 piglets and the pens housing 12 piglets.
A point of discussion should be the fibre length, which was relatively short (about 50 mm) in
both materials. Day et al. (2008) concluded that the number of tail-biting incidents was higher
in groups with short-chopped straw (mostly 1 to 40 mm) in comparison to partially chopped
(mostly 40 to 70 mm) or long fibre straw (mostly over 70 mm). Nevertheless, based on
experiences from other on-farm studies in which long fibre straw (over 70 mm) led to massive
problems with the slurry system the decision was made to find a trade-off between suitable
materials for piglets and intensive housing systems (Van de Weerd and Day, 2009).
Furthermore, the offering scheme per day should be discussed. In the environmental
enrichment study an effort was made to provide the material twice a day, whereas the offering
scheme in the weaning management study was only once per day. In this study, only small
pens were used and the offering scheme was a relief for the stable staff in order to save time.
Nevertheless, the material did often not last throughout the day and empty piglet bowls can
also be seen as a frustrating factor in the pen. Munsterhjelm et al. (2009) concluded that
moderate bedding of farrowing pens reduces agonistic behaviour later in life, although
85
removal of it increases redirected behaviour, including tail-biting. This might have been
problematic in the environmental enrichment study; the piglets from the raw material groups
did not receive alfalfa hay and corn silage during fattening. The results show that piglets
which received raw material from the second week of life until the end of rearing lost their
tails to a larger extent during fattening (20 %) than piglets out of the control groups (5 %).
Thus, as stated by Munsterhjelm (2009), the withdrawal of material provided in former stages
of life can be interpreted as a frustration factor which could have provoked tail-biting in the
subsequent fattening period. Additionally, Day et al. (2002) proved that moving pigs from
previously straw-bedded accommodation to not straw-bedded accommodation increases the
occurrence of adverse pen-mate-directed behaviour.
Moreover, it is important to mention the renewing aspect of raw material provision as
described by Moinard et al. (2003) and Hunter et al. (2001). The material remained of interest
to the animals as long as it was renewed regularly and did not smell like the pen surroundings
or the piglets themselves. This cannot be guaranteed by occupation material which is
permanent available in the pen such as chains, plastic balls or wooden sticks. Wood-Gush and
Vestergard (1991) proved piglets’ preference for novelty when offered a familiar object in
comparison to a novel object. This emphasises piglets’ curiosity and the value of frequent
renewal of manipulable material. Especially dried corn silage seemed to be suitable to
stimulate the exploratory behaviour of the piglets for a certain length of time. This finding
contributes to Studnitz et al. (2007), who concluded that if the material is complex and if it is
changeable as well as destructible, the novelty value will be maintained. Furthermore, if the
materials contain edible parts, the foraging behaviour as well as the curiosity of the pigs will
be stimulated.
Weaning management
The starting point of tail-biting was detected in both studies in the second week after weaning,
which implicates a relation to the weaning process. Martin (1984) defined weaning as the
period when the drop in parental investment per unit time is the largest. Under “natural
conditions” weaning is a gradual process and in piglets is not completed until 10–12 weeks of
age (Lallès et al., 2007). The piglets are taught how to feed and to root and learn to establish
their hierarchy in the group (Oostindjer et al., 2014). In a current study the effect of a
86
prolonged suckling period in a group farrowing system is being tested in order to evaluate
whether the piglets’ behaviour is positively influenced by the longer presence of the sow.
What needs to be evaluated here is whether abnormal behaviour re-surfaces in connection
with the weaning process as in previous studies or at another point of time. Nevertheless, the
abrupt change in housing environment and separation from the sow as well as the
confrontation with unfamiliar pen mates requires a high coping ability of the piglets. Stress
physiology is often called physiology of adaption. Any challenge facing an animal leads to a
modification of the functioning of that animal, and this change prepares the animal to better
cope with further challenges (Veissier and Boissy, 2007). Tail-biting as a stress-induced
behavioural disorder (Sinisalo et al., 2012) is caused by several risk factors which can
accumulate and influence the overall risk of an individual piglet to show abnormal behaviour
(EUWelNet, 2013). Wiepkema and Van Adrichem (1987) described that conflict behaviour
arises during acute stress, whereas chronic stress brings about disturbed behaviour such as
stereotypes. An animal is said to be in a state of stress if it is required to make abnormal or
extreme adjustments concerning its physiology or behaviour in order to cope with the adverse
aspects of its environment and management (Fraser et al., 1975). Coping is defined as a
behavioural response that aims at reducing the effect of aversive stimuli (Wechsler, 1995).
Welfare is defined as the state of physical and mental health resulting from the process of
behavioural and physiological adaptation when coping successfully with environmental
challenges (Puppe et al., 2012). In intensive housing systems, however, the animals often fail
to counteract aversive situations by using these evolved coping strategies, and it is argued that
abnormal behaviour can originate from unsuccessful coping behaviour (Wechsler, 1995).
Both failure to cope with the environment and difficulty in coping are indicators of poor
welfare (Broom, 1991).
Is the weaning process one of the triggering factors which can provoke subsequent tail-biting
behaviour or does the weaning process occupy the piglets with the exploration of new
environmental surroundings, as well as the meeting of new pen mates? Expressing it in more
abstract manner: Are the piglets’ overwhelmed by today’s management practices (such as
regrouping, rehousing…) and do we overtax their adaptive abilities or, have the piglets with
their individual coping strategies which enable them to react to environmental changes
developed such a flexibility that a “standstill”, which is provoked e.g. by barren rearing pens,
87
results in frustration and boredom? Korte et al. (2007) assumed that not constancy or
freedoms, but capacity to change is crucial to good physical and mental health and good
animal welfare.
Underlying mechanisms and coping strategies
Tail-biting occurred in both studies regardless of the treatment groups. The variable results
suggest a connection between the behavioural disorder and the individual character of the
piglets, which was detected by video analysis in the weaning management study. Dantzer and
Mormède (1983) stated that behavioural responses follow two opposite modes, a passive
mode (e.g. freezing) vs. an active mode (e.g. fight/ flight), which (both) depend on the
individual’s genetic background and prior experience. Hessing et al. (1993) found proof of the
existence of behavioural strategies to cope with conflict situations in piglets. Koolhaas et al.
(1999) concluded that there are distinct phenotypes (proactive and reactive coping styles)
which are more or less stable over time in their response to stressors and, thus, may adapt
differentially to environmental conditions. Transferring this assumption to the results of the
video analysis, the coping style of receivers of tail-biting would be classified as passive since
they stop to perform overt behaviour when exposed to an aversive situation and wait for a
change (Wechsler, 1995). Performers on the other hand could be seen as active coping types,
which react to aversive situations with abnormal behaviour. Korte et al. (2009) assumed that
artificial genetic selection (fast growth, leaner meat, larger muscle volume) results in the
production of farm animals that prefer the aggressive hawkish behavioural strategy and, thus,
have a higher risk of developing violence and stereotypes. Nevertheless, focusing on welfare
aspects in breeding, it needs to be kept in mind that breeding against behavioural measures of
welfare could inadvertently result in resilient animals that do not show behavioural signs of
low welfare yet may still suffer (D'Eath et al., 2010).
Prediction of tail-biting events on commercial farms
One part of animal behaviour important for the prediction of tail-biting outbreaks is tail
posture. In the course of both studies, no data on this trait were collected, but direct
observations made during the weekly scoring gave an indication that tail posture is linked
with tail-biting outbreaks. In case of an incidence in a pen, the piglets waved their tails more
88
frequently and piglets which had already received bites, tucked their tails under to prevent
further manipulation. This contributes to the study of Zonderland et al. (2009), who concluded
that a piglet’s tail posture is strongly related to tail damage at the same moment and can
predict tail damage two to three days later. Thus, long tails in piglets can be used as an “early
alert” system, since any management problem which causes tail-biting, such as dysfunction in
feed- or water accessibility as well as climate deficiency, could then be detected.
Another observation that could be made was the piglets’ behaviour when entering the pen in
order to score the tails. In pens with tail-biting outbreaks, the piglets showed different
behaviour towards the observer. This trait was subjectively evaluated and not consequently
documented during the studies. In the case of a tail-biting outbreak, piglets were more
obtrusive, searched contact with the observer more quickly, and manipulated the observer
more frequently. The most possible objective way of assessing this is probably the human
approach test. In this test, a human enters a pen and documents the latency until the piglets
perform their first physical contact with the observer (Brown et al., 2009).
Furthermore, there is evidence that changes in feeding patterns are connected with tail-biting
outbreaks. Wallenbeck and Keeling (2013) showed that low frequencies of daily feeder visits
observed at group level can predict future tail-biting in the pen as early as nine weeks before
the first tail injuries. Therefore, feed consumption could be a parameter which should be
considered in further studies.
Recommendations for further research
In both studies, the animal to feeding place ratio was 2:1, which inhibited stress-free feed
intake for the piglets. An insufficient animal to feeding place ratio increases the risk for tail-
biting (Hansen et al., 1982; Moinard et al., 2003). Evaluations should be carried out as to
whether a ratio of 1:1 has positive effects on the development of the behavioural disorder.
Another aspect could be feed composition (especially crude fibre content) and the dosage
form of feed (liquid vs. dry), since information available in literature is inconsistent.
A further focus should be put on genetics since there is an indication that a higher lean meat
content and decreasing back fat thickness is connected with increasing frequencies of tail-
biting (Moinard et al., 2003). In the last few decades, consumers have shown a growing
interest in higher lean meat content due to fitness aspects, which have resulted in a more
89
targeted selection. It needs to be clarified whether the breeding in turn affected the piglets’
behaviour as mentioned above.
Individuals which showed the obsessive form of tail-biting, as described by Taylor et al.
(2010), could be detected by direct and video observation in both studies. If these animals
tail-biting as a stereotype developed due to chronic stress probably caused by health problems
or malnutrition cannot be sufficiently clarified. A point of interest in identified biters would
be the analysis of blood and brain serotonin measures, which are related to dietary tryptophan
supply and play an important role in stress metabolism (Koopmans et al., 2006). The results
of Ursinus et al. (2013) suggest a role of serotonin in biological traits underlying the
behavioural responses of pigs during a challenging situation.
Moreover, diseases such as infections caused by E.coli and Streptococcus suis occurred in
both studies and probably led to increasing tail-biting behaviour in affected pens and units,
subsequently. There are indications that a proper health status is of crucial importance in the
prevention of tail-biting (Moinard et al., 2003; Walker and Bilkei, 2006); pigs which are
infected may be more reluctant to defend themselves against being bitten (Kritas and
Morrison, 2004). The serum acute phase proteins haptoglobin, respectively C-reactive protein,
as indicators of inflammatory reactions can provide an important marker for swine health
status in further studies (Chen et al., 2003).
References
Broom, D. M. 1991. Animal welfare: Concepts and measurement. Journal of Animal Science
69: 4167-4175.
Brown, J. A. et al. 2009. Reliability of temperament tests on finishing pigs in group-housing
and comparison to social tests. Applied Animal Behaviour Science 118: 28-35.
Chen, H.-H. et al. 2003. Serum acute phase proteins and swine health status. Canadian Journal
of Veterinary Research 67: 283-290.
D'Eath, R. B., J. Conington, A. B. Lawrence, I. A. S. Olsson, and P. Sandøe. 2010. Breeding
for behavioural change in farm animals: Practical, economic and ethical
considerations. Animal Welfare 19: 17-27.
Dantzer, R., and P. Mormède. 1983. Stress in farm animals: A need for reevaluation. Journal
of Animal Science 57: 6-18.
90
Day, J. E. L. et al. 2002. The effects of prior experience of straw and the level of straw
provision on the behaviour of growing pigs. Applied Animal Behaviour Science 76:
189-202.
Day, J. E. L., H. A. Van de Weerd, and S. A. Edwards. 2008. The effect of varying lengths of
straw bedding on the behaviour of growing pigs. Applied Animal Behaviour Science
109: 249-260.
Douglas, C., M. Bateson, C. Walsh, A. Bédué, and S. A. Edwards. 2012. Environmental
enrichment induces optimistic cognitive biases in pigs. Applied Animal Behaviour
Science 139: 65-73.
EUWelNet. 2013. http://euwelnet.hwnn001.topshare.com/. 10 November 2015.
FAWC. 1979. First press notice, 5/ 12. MAFF, London, England, UK.
Fraser, D., J. S. Ritchie, and A. F. Fraser. 1975. The term" stress" in a veterinary context. The
British Veterinary Journal 131: 653.
Hansen, L. L., A. M. Hagelsø, and A. Madsen. 1982. Behavioural results and performance of
bacon pigs fed ad libitum from one or several self-feeders. Applied Animal Ethology
8: 307-333.
Hessing, M. J. C. et al. 1993. Individual behavioural characteristics in pigs. Applied Animal
Behaviour Science 37: 285-295.
Hunter, E. J., T. A. Jones, H. J. Guise, R. H. C. Penny, and S. Hoste. 2001. The relationship
between tail biting in pigs, docking procedure and other management practices. The
Veterinary Journal 161: 72-79.
Koolhaas, J. M. et al. 1999. Coping styles in animals: Current status in behavior and stress-
physiology. Neuroscience & Biobehavioral Reviews 23: 925-935.
Koopmans, S. J. et al. 2006. Effects of supplemental -tryptophan on serotonin, cortisol,
intestinal integrity, and behavior in weanling piglets. Journal of Animal Science 84:
963-971.
Korte, S. M., B. Olivier, and J. M. Koolhaas. 2007. A new animal welfare concept based on
allostasis. Physiology & Behavior 92: 422-428.
Korte, S. M., J. Prins, C. H. Vinkers, and B. Olivier. 2009. On the origin of allostasis and
stress-induced pathology in farm animals: Celebrating darwin's legacy. The Veterinary
Journal 182: 378-383.
91
Kritas, S. K., and R. B. Morrison. 2004. An observational study on tail biting in commercial
grower-finisher barns. Journal of Swine Health and Production 12: 17-22.
Lallès, J.-P., P. Bosi, H. Smidt, and C. R. Stokes. 2007. Weaning - a challenge to gut
physiologists. Livestock Science 108: 82-93.
Martin, P. 1984. The meaning of weaning. Animal Behaviour 32: 1257-1259.
Moinard, C., M. Mendl, C. J. Nicol, and L. E. Green. 2003. A case control study of on-farm
risk factors for tail biting in pigs. Applied Animal Behaviour Science 81: 333-355.
Munsterhjelm, C. et al. 2009. Experience of moderate bedding affects behaviour of growing
pigs. Applied Animal Behaviour Science 118: 42-53.
Oostindjer, M., B. Kemp, H. van den Brand, and J. E. Bolhuis. 2014. Facilitating "Learning
from mom how to eat like a pig" To improve welfare of piglets around weaning.
Applied Animal Behaviour Science 160: 19-30.
Puppe, B., M. Zebunke, S. Düpjan, and J. Langbein. 2012. Kognitiv-emotionale
Umweltbewältigung beim Hausschwein - Herausforderung für Tierhaltung und
Tierschutz. Züchtungskunde 84: 307-319.
Sinisalo, A., J. K. Niemi, M. Heinonen, and A. Valros. 2012. Tail biting and production
performance in fattening pigs. Livestock Science 143: 220-225.
Studnitz, M., M. B. Jensen, and L. J. Pedersen. 2007. Why do pigs root and in what will they
root?: A review on the exploratory behaviour of pigs in relation to environmental
enrichment. Applied Animal Behaviour Science 107: 183-197.
Taylor, N. R., D. C. J. Main, M. Mendl, and S. A. Edwards. 2010. Tail-biting: A new
perspective. The Veterinary Journal 186: 137-147.
Ursinus, W. W. et al. 2013. Relations between peripheral and brain serotonin measures and
behavioural responses in a novelty test in pigs. Physiology & Behavior 118: 88-96.
Van de Weerd, H. A., and J. E. L. Day. 2009. A review of environmental enrichment for pigs
housed in intensive housing systems. Applied Animal Behaviour Science 116: 1-20.
Van de Weerd, H. A. V. d., C. M. Docking, J. E. L. Day, K. Breuer, and S. A. Edwards. 2006.
Effects of species-relevant environmental enrichment on the behaviour and
productivity of finishing pigs. Applied Animal Behaviour Science 99: 230-247.
Veissier, I., and A. Boissy. 2007. Stress and welfare: Two complementary concepts that are
intrinsically related to the animal's point of view. Physiology & Behavior 92: 429-433.
92
Walker, P. K., and G. Bilkei. 2006. Tail-biting in outdoor pig production. The Veterinary
Journal 171: 367-369.
Wallenbeck, A., and L. J. Keeling. 2013. Using data from electronic feeders on visit
frequency and feed consumption to indicate tail biting outbreaks in commercial pig
production. Journal of Animal Science 91: 2879-2884.
Wechsler, B. 1995. Coping and coping strategies: A behavioural view. Applied Animal
Behaviour Science 43: 123-134.
Wiepkema, P. R., and P. W. M. Van Adrichem. 1987. Behavioural aspects of stress biology of
stress in farm animals: An integrative approach. Current topics in veterinary medicine
and animal science No. 42. p 113-133. Springer Netherlands.
Wood-Gush, D. G. M., and K. Vestergaard. 1991. The seeking of novelty and its relation to
play. Animal Behaviour 42: 599-606.
Zonderland, J. J. et al. 2009. Tail posture predicts tail damage among weaned piglets. Applied
Animal Behaviour Science 121: 165-170.
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Christina Veit: Influence of raw material and weaning management on the occurrence
of tail-biting in undocked pigs
GENERAL SUMMARY
The aim of the present thesis was the evaluation of tail-biting behaviour in pigs in order to
gain further information on the causes and the underlying mechanism of this abnormal
behaviour. Therefore, two different experimental set-ups concerning environmental
enrichment and weaning management were carried out under practical conditions.
The focus of the environmental enrichment study was on the effect of manipulable material
provided for long-tailed piglets. In addition to former studies in this research field, the focus
was given to the farrowing and rearing phases instead of the fattening period. Two different
substrates, dried corn silage (SG, n = 245) and alfalfa hay (AG, n = 245) were provided to the
piglets twice per day from the second week of life until the end of rearing. A control (CG,
n = 231) were kept without provision of additional raw material. The focus of the second
study was on weaning management, since reliable information of its effect on tail-biting is
still missing. The hypothesis proposed was that the avoidance of stress through mixing after
weaning has positive effects on the manifestation of behavioural disorders. In total, 478 long-
tailed piglets were divided into two groups, 240 piglets were housed in litter groups (LG),
whereas 238 piglets were mixed at least out of three different litters (MG). The data in both
studies were collected with a scoring scheme regarding tail lesions/ tail losses once per week
with a four-point score (0 = no damage/ original length of tail to 3 = severe damage/ total loss
of tail). In the environmental enrichment study, video observations of 99 piglets during
farrowing and 188 piglets during rearing delivered additional data on the activity behaviour at
group level and the piglets’ occupation with the material provided. The focus of video
observation in the weaning management study was on manipulative behavioural patterns and
piglets’ behaviour prior to a tail-biting outbreak. Recorded video material of five pens (60
piglets) was under analysis by instantaneous scan sampling and continuous observation.
Based on the frequencies of the manipulative behaviour performed, each piglet produced a
character score, which enabled it to be classified as a performer, neutral or a receiver of
manipulative behavioural patterns.
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The results in both studies were similar regarding the tested effect of week after weaning on
tail lesions and tail losses. Tail-biting started on average two to three weeks after weaning,
followed by tail losses one to two weeks later. A finding which can be explained by several
conversions piglets are faced with during the weaning process. Separation from the sow and
adaption to a new environment (social and spatial) contribute to stressful situations for the
piglets. If they fail to cope with these challenges, piglets could develop tail-biting behaviour.
In the environmental enrichment study, the amount of tail losses decreased with the number
of batches (96.4 % in batch one vs. 7.4 % in batch ten). This can be explained by an enhanced
and more precise animal observation by stable staff and points out the learning process in the
course of the study. Piglets out of all batches lost their tails to the greatest extent in CGs
(50.4 %), followed by AGs (49.2 %) and SGs (30.2 %) at the end of rearing. Curative
measures were also carried out in CGs to avoid severe injuries and welfare problems in the
case of tail-biting outbreaks. Thus, CGs were falsified, which could have led to an
approximation of raw material groups and control groups. The number of tail lesions and tail
losses in the weaning management study differed without a clear trend between the treatment
groups and the batches. This finding could be explained by the different forms of tail-biting.
Two stage tail-biting is longer lasting than sudden forceful tail-biting, thus, the first form was
probably detected more securely during weekly scoring. Furthermore, dysfunctions in water
or feed accessibility or climate variations within the units could have provoked behavioural
disorder. The daily weight gain of the piglets showed no clear trend over treatment groups and
batches and could not be connected with the weekly scoring of tail lesions and tail losses in
both studies.
Corn silage stayed attractive for the piglets during the whole observation period in the
environmental enrichment study, whereas the acceptance of alfalfa hay decreased towards the
end of rearing. This could be explained by a better palatability of corn silage due to higher
concentrations of carbohydrates and lower dry-matter content. There was no clear trend
between activity behaviour and the level of tail-biting within the batches. The pen mate-
directed behaviour tail exploration in the weaning management study increased over five days
prior to a scored tail-biting outbreak. The frequencies of belly nosing were highest in the pen
which was observed closest to weaning, which indicates a connection to the weaning process.
The receivers of nosing behaviour lay more frequently than the performers, thus, they reacted
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less defensively and tolerated manipulations with the snout more frequently, whereas
performers showed higher general activity.
A provision of raw material from the second week of life until the end of rearing and a
renunciation of mixing after weaning cannot prevent tail-biting during rearing. Rearing of
long-tailed pigs requires intensive animal observation and direct intervention in the case of
tail-biting outbreaks, provision of raw material as manipulable material is useful. There were
clear differences in individual pig characters and it needs to be taken into account that every
piglet has different coping strategies to react to environmental changes. Today’s conventional
husbandry systems could overtax this adaptive capacity of the piglets. Therefore, housing
should be adapted further in a way which meets the demands of natural behaviour in pigs.
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Christina Veit: Influence of raw material and weaning management on the occurrence
of tail-biting in undocked pigs
Zusammenfassung
Das Ziel der vorliegenden Dissertation war die Evaluierung von Schwanzbeißverhalten beim
Schwein um weitergehende Informationen über die Ursachen und zugrundeliegenden
Mechanismen des Fehlverhaltens zu erlangen. Hierfür wurden unter Praxisbedingungen zwei
verschiedene Studien mit den Schwerpunkten Beschäftigungsmaterial und
Absetzmanagement durchgeführt.
Der Fokus der ersten Studie lag auf dem Effekt von manipulierbarem Material für unkupierte
Schweine. Im Gegensatz zu früheren Studien in diesem Forschungsgebiet wurden die Säuge-
und Aufzuchtsphase, anstelle der Mastperiode untersucht. Zwei verschiedene Materialien,
getrocknete Maissilage (SG, n = 245) und Luzerneheu (AG, n = 245) wurden den Ferkeln
zweimal täglich von der zweiten Lebenswoche bis zum Ende der Aufzucht angeboten. Eine
Kontrolle (CG, n = 231) wurde ohne zusätzliches Beschäftigungsmaterial gehalten. Der Fokus
der zweiten Studie lag auf dem Absetzmanagement, weil zuverlässige Informationen zum
Einfluss auf Schwanzbeißen fehlen. Es wurde die Hypothese aufgestellt, dass die Vermeidung
von Stress durch Mischen nach dem Absetzen positive Effekte auf die Manifestierung von
Verhaltensstörungen hat. Insgesamt wurden 478 unkupierte Ferkel in zwei Gruppen geteilt,
240 Ferkel wurden wurfweise aufgestallt (LG), während 238 Ferkel aus mindestens drei
Würfen gemischt wurden (MG). In beiden Studien wurden die Daten mit Hilfe eines
Boniturschemas wöchentlich aufgenommen, dabei wurden Schwanzverletzungen
und -verluste durch einen vierstufigen Schlüssel bewertet (0 = keine Verletzungen/
Originallänge bis 3 = großflächige Verletzung/ Komplettverlust des Schwanzes). In der Studie
zum Beschäftigungsmaterial wurden zusätzlich Videobeobachtungen von 99 Ferkeln in der
Säugephase und 188 Ferkeln in der Aufzucht erhoben und lieferten Daten über das
Aktivitätsverhalten auf Buchtenebene und die Beschäftigung der Ferkel mit dem angebotenen
Material. Der Fokus der Videobeobachtungen in der Absetzmanagementstudie lag auf
manipulativen Verhaltensweisen und dem Schweineverhalten vor einem
Schwanzbeißausbruch. Aufgenommenes Videomaterial von fünf Buchten (60 Ferkel) wurde
mittels „Instantaneous scan sampling“ und kontinuierlicher Beobachtung ausgewertet. Auf
97
der Grundlage der Häufigkeiten des ausgeübten manipulativen Verhaltens erhielt jedes Ferkel
einen Charakterschlüssel, welcher eine Klassifizierung in Ausführender bzw. Empfänger von
manipulativen Verhaltensweisen oder neutraler Charakter ermöglichte.
Der Effekt der Woche nach dem Absetzen auf Schwanzverletzungen und –verluste war in
beiden Studien ähnlich. Schwanzbeißen begann im Schnitt zwei bis drei Wochen nach dem
Absetzen, gefolgt von Schwanzverlusten ein bis zwei Wochen später. Eine Erkenntnis, die
durch verschiedene Veränderungen erklärt werden kann, mit der die Ferkel durch das
Absetzen konfrontiert sind. Die Trennung von der Muttersau und die Anpassung an eine neue
Umgebung (sozial und räumlich) tragen zu einer belastenden Situation für die Ferkel bei.
Falls es ihnen nicht gelingt, diese Herausforderungen zu bewältigen, könnten die Ferkel
Schwanzbeißverhalten entwickeln. In der Studie zum Beschäftigungsmaterial nahm die Zahl
der Schwanzverluste mit der Anzahl der Durchgänge ab (96.4 % im ersten Durchgang vs.
7.4 % im zehnten Durchgang). Dies kann durch eine verbesserte und präzisere
Tierbeobachtung durch das Stallpersonal erklärt werden und stellt einen Lernprozess im
Verlauf der Studie dar. Ferkel aus allen Durchgängen hatten die meisten Schwanzverluste am
Ende der Aufzucht in CGs (50.4 %) zu verzeichnen, gefolgt von AGs (49.2 %) und SGs
(30.2 %). Kurative Maßnahmen wurden im Falle von Schwanzbeißausbrüchen auch in CGs
durchgeführt, um schwerwiegende Verletzungen und Einschränkungen des Tierwohls zu
vermeiden. Dementsprechend wurden CGs verfälscht, was möglicherweise zu einer
Annährung von Raufuttergruppen und Kontrollgruppen geführt hat. Die Zahl der
Schwanzverletzungen und -verluste in der Absetzmanagementstudie unterschieden sich ohne
einen deutlichen Trend zwischen den Versuchsgruppen und den Durchgängen. Diese
Feststellung konnte durch die verschiedenen Formen von Schwanzbeißen erklärt werden.
„Zweistufiges Beißen“ stellt einen länger andauernden Prozess dar als „plötzlich-gewaltsames
Beißen“; möglicherweise war die erste Form dadurch sicherer durch die wöchentliche Bonitur
festzustellen. Darüber hinaus könnten Ausfälle in der Wasser- und Futterversorgung oder
Veränderungen im Abteilklima die Verhaltensstörung ausgelöst haben. Die täglichen
Zunahmen folgten keinem klaren Trend über die Versuchsgruppen und die Durchgänge und
konnten in keiner der beiden Studien mit der wöchentlichen Bonitur von
Schwanzverletzungen und –verlusten in Verbindung gebracht werden.
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In der Studie zum Beschäftigungsmaterial blieb Maissilage während der gesamten
Beobachtungsperiode attraktiv für die Ferkel, während die Akzeptanz von Luzerneheu gegen
Ende der Ferkelaufzucht abnahm. Dies könnte mit einer besseren Schmackhaftigkeit der
Maissilage durch eine höhere Konzentration von Kohlenhydraten und einem geringeren
Trockenmassegehalt erklärt werden. Es konnte kein klarer Trend zwischen dem
Aktivitätsverhalten und dem Schwanzbeißniveau innerhalb der Durchgänge festgestellt
werden. Das gegen Buchtengenossen gerichtete Verhalten “Tail exploration” in der
Absetzmanagementstudie stieg fünf Tage vor einem bonitierten Schwanzbeißausbruch an. Die
Häufigkeiten von „Belly Nosing“ waren am höchsten in der Bucht, die am nächsten zum
Absetzen beobachtet wurde, was eine Verbindung zum Absetzprozess vermuten lässt. Die
Empfänger von „Nosing“ lagen häufiger als die Ausüber dieses Verhaltens, dementsprechend
reagierten sie weniger defensiv und tolerierten die Manipulationen mit der Schnauze häufiger,
während die Ausführenden eine höhere Gesamtaktivität zeigten.
Ein Angebot von Raufutter ab der zweiten Lebenswoche bis zum Ende der Ferkelaufzucht
und ein Verzicht auf das Mischen von Würfen nach dem Absetzen kann Schwanzbeißen nicht
verhindern. Die Aufzucht von unkupierten Schweinen erfordert eine intensive
Tierbeobachtung und sofortiges Eingreifen im Falle von Schwanzbeißausbrüchen, das
Angebot von Raufutter, als manipulierbares Material, ist von Nutzen. Es gab klare
Unterschiede im individuellen Charakter der Schweine und es muss beachtet werden, dass
jedes Ferkel verschiedene Bewältigungsstrategien besitzt, um auf Änderungen seiner Umwelt
zu reagieren. Die heutigen Haltungssysteme könnten diese Anpassungsfähigkeit der Ferkel
überfordern. Demnach sollten die Haltungsbedingungen weiter angepasst werden, um
Schweinen ein Verhalten zu ermöglichen, das ihren natürlichen Bedürfnissen entspricht.
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