-
Negative impacts dueto infectious diseasesare considerablein
various types ofaquaculture, and. cost millions ofdollars in lost
revenues due tomortality and reduced productionefficiency.
Therefore, interest continues indeveloping alternatives to
traditionalmeans of combating diseases. Although theconcept of
functional feeds is relatively newto the aquaculture industry, it
representsan emerging new paradigm to developdiets that extend
beyond satisfying basicnutritional requirements of the cultured
organism to improving health and resistanceto stress and
disease-causing organisms(Gatlin 2002).
Disease prevention and treatmentstrategies, such as use of
vaccines and drugs,ar.e generally limited in most
aquaculturaloperations due to regulatory constraints orinconvenient
administration options.
Therefore, our laboratory has
Cumulative Survival (%)
investigated the effects of various dietaryfactors on disease
resistance as well asimmunostimulation of various fish species.
This research has focused on selectednutrients such as arginine,
vitamin C, vitaminE and selenium, as well as various
naturalfeedstuffs and synthetic compounds whichmay enhance immunity
and fish health.
181 INTERNATIONAL AQUAFEED I November-December 08
PrebioticsPrebiotics are defined as non-digesti
food ingredients which beneficially affectthe host by
selectively stimulating thegrowth of and/or activating the
metabolisof one or a limited number of healpromoting bacteria in
the intestinal tract,thus improving the host's intestinal
balance(Gibson and Roberfroid 1995).
Some researchersalso have suggested thatthe interaction
betweenintestinal microflora anenterocytes may triggerrelease of
biologically-active substances aninfluence host immunity(reviewed
by Pattersoand Burkholder 2003)_The health-promotingbacteria most
commonlyaugmented by prebioticsinclude those of thegenus
.Lactobacillus andBifidobacter which tendto limit the presence
ofharmful bacteria.
Examples of prebiotics includemannanoligosaccharides (White et
al2002), lactose (Szilagyi 2002), as well asoligofructose and
inulin (Teitelbaum andWalker 2002). These natural compoundsare
generally not altered by diet processingand require limited
regulatory approsuch that their incorporation into diets is
-
much simpler than required for drugs orchemical therapeutic
agents.
EvaluationTo explore potential use of a specialised
prebiotic preparation in aquaculture, ourlaboratory first
evaluated the commercialproduct GroBiotic®-A in three
separatefeeding trials with hybrid striped bass(Morone chrysops x
M. saxatilis).
This product is a mixture of partiallyautolyzed brewers yeast,
dairy ingredientcomponents and dried fermentationproducts
containing 35.2 percent crudeprotein, 1.7 percent crude lipid and
-53percent simple and complex carbohydratesincluding
oligosaccharides. Hybrid stripedbass is an important aquacultured
fish inthe United States and is negatively impactedby various
bacterial pathogens, such asStreptoccocus iniae and
Mycobacteriummarinum (Plumb 1997).
In each of the three trials with hybridstriped bass, a basal
diet was formulatedto contain 40 percent crude protein,· 10percent
lipid and 14.6kJ digestible energy/g.
Experimental diets were supplementedwith GroBiotic®-A at either
onepercent or two percent of dry weightand maintained
isonitrogenous andisoenergetic by adjusting the amount offishmeal
and dextrin. After a seven-weekperiod in the first feeding trial,
Significantlyenhanced weight gain (percent of initialweight) and
feed efficiency (gram weight
gain/g feed) were observed in juvenile fish(initial weight of
seven glfish) fed dietssupplemented with one or two
percentGroBiotic®-A compared to those fed thebasal diet (Li and
Gatlin 2004). Survivalduring the first feeding trial was high andno
significant differences were observedamong treatments.
In the second feeding trial, survival ofjuvenile fish (initial
weight of 19.7g/fish)fed diets containing GroBiotic®-A for
fourweeks and then exposed by immersion to a
The shortness of the trial did not allowfor separation of
juvenile hybrid stripedbass performance as influenced by
dietaryGroBiotic®-A, thus no significant differenceswere observed
in this regard.
Further studyTo further explore possible age/size-
related responses, a 2 I-week feeding trialwas conducted to
evaluate GroBiotic®-Ain the diet of sub-adult hybrid striped
bass(initial weight of 65-1 IBg/fish) exposed to.
o protein• organic mattero lipid8 energy
Figure 2: Digestibilitycoefficients of diets fedto the red drum.
Basaland GroBiotic-A dietscontained 40 percentcrude protein
fromapproximately halfdehulled soybean mealand half
menhadenfishmeal while thecontrol diet had all ofits protein
provided bymenhaden fishmeal (FMcontrol)
Digestibility coefficients of diets fed to red drum
gOf~~~~lfit3rjf~~8580C ~~~ 65'" 60Q. 55
504540
f--f--
IBurr et a!. (2008\ Aquaculture Res. In press
standardized dose of Streptococcus iniae wassignificantly (P
< 0.0 I) higher than fish fedthe basal diet (Li and Gatlin
2004).
Extra cellular superoxide anionproduction of head kidney
macrophagesfrom fish fed GroBiotic®-A or brewersyeast also was
Significantly higher than thatof fish fed the basal diet.
November-December 081 INTERNATIONAL AQUAFEED 119
1'=0.001
a chronic mycobacterial infection causedby Mycobacterium marinum
(Li and Gadin2005).
Enhanced growth performancewas generally observed in fish fed
dietssupplemented with GroBiotic®-A comparedto fish fed the basal
diet throughout thefeeding trial with Significantly (P <
0.05)
-
Prebioticenhanced weight gain observed after 12weeks of feeding.
The in situ mycobacterialchallenge employed in this
experimentresulted in overall cumulative mortality ofapproximately
25 percent.
Fish fed two percent Grobiotic®-Ahad a significantly (P <
0.05) enhancedsurvival (80 percent) compared to theother treatments
(72-73 percent) at theend of 21 weeks. It is known that ingestionof
feed is a port of entry for mycobacteriain fish such as the
snakehead Channa striatus(Chinabut et al. 1990). This could
possiblybe a factor contributing to the positiveresponse associated
with the GroBiotic®-Asupplement.
In vivo experimentsBased on the positive results obtained
with hybrid striped bass, we evaluatedGroBiotic®-A in a series
of in vitro and invivo experiments with red drum
(Sciaenopsocel/atus), a marine sciaenid cultured forfood and stock
enhancement along the Gulfand Atlantic coasts of the United
States.
An in vitro experiment revealed thatGroBiotic®-A altered the
microbialcomposition of GI tract inoculum fromred drum, and the
predominant microbialspecies was of the genus Lactococcus based
on DNA sequencing (Burr et al. 2008a).In a subsequent study, red
drum
fed a diet containing 40 percent crudeprotein provided equally
from soybeanmeal and fishmeal and supplementedwith GroBiotic®-A at
one percent hadsignificantly elevated digestibility coefficientsfor
crude protein, organic matter, lipid andenergy compared to a basal
diet withoutprebiotic supplementation (see Figure 2)(Burr et al.
2008b). The prebiotic-inducedenhanced digestibility of the
soybeanmeallfishmeal diet was comparable to thatobserved for the
control diet in which all ofits protein originated from
fishmeal.
Another feeding trial was then conductedwith red drum to
evaluate their growthperformance, non-specific immune responsesand
resistance to Amyloodinium ocel/atum,a parasitic dinoflagellate
which may causesevere losses to various marine fishes.
In this feeding trial, red drum werefed soybean meal/fish
meal-based dietsas previously described, and exposed toAmyloodinium
ocel/atum after four weeksof feeding. Fish fed GroBiotic®-A at
onepercent of diet had significantly enhancedweight gain, feed
efficiency and survival(see Figure 3) after week six (Buentello
etal. 2008).
Survival of red drum exposed toAmyloodinium ocellatus for 2
weeks
Basal GroBiotic-A
Diet
Cumulative Mortality of Rainbow TroutExposed to Infectious
Hematopoietic
Necrosis Virus
~Ar~ __ -----------------'
70
it 60~50
i:"'20100~L-~~~~~~~~===7
Diet IP injection after 9 w'Ic feeding
seaiev et at, (2007) N. Am. J. Acuecutt, 69:400-406
20 I INTERNATIONAL AQUAFEED I November-December 08
In addition, red drum fed the dietsupplemented with GroBiotic®-A
hadsignificantly elevated non-specific immumeresponses including
serum lysozyme andintracellular superoxide anion production.The
evaluation of GroBiotic®-A also hasbeen extended to other fish
species such asrainbow trout Oncorhynchus mykiss (Sealeyet al.
2007) and golden shiner Notemigonuschrysoleucus, the predominant
minnowspecies cultured in the United States for bait(Sink et al.
2007, Sink and Lochmann 2008).
In the study with rainbow trout,supplementation of GroBiotic®-A
at twopercent of diet significantly increased feedefficiency at
week three, although thedifference was not statistically distinct
byweek nine.
However, fish fed the diet supplementedwith GroBiotic®-A had
significantly greatersurvival after exposure to
infectioushematopoietic necrosis virus (see Figure 4).
Two separate feeding trials have beenconducted with golden
shiners in which theywere fed various practical diets
includingthose supplemented with GroBiotic®-Aat two percent by
weight. In one trial,golden shiners were fed diets containingfour
or 10 percent lipid without prebioticsupplementation and one with
10 percentlipid and supplemented with GroBiotic®-Afor 16 weeks
(Sink et al. 2007).
After the feeding trial, fish were subjectedto a Flavobacterium
columnare challengeby immersion. Fish fed the
prebiotic-supplemented diet had significantly lowermortality
compared to fish fed the otherdiets (see Figure 5).
In another subsequent experiment(Sink and Lochmann (2008),
goldenshiners were fed diets with or withoutsupplemental
GroBiotic®-A for 10 weeks.Groups of fish fed each diet were
eithersubjected to handling stress or directlyexposed to
Flavobacterium columnareby immersion. Handling stress prior
todisease exposure significantly increasedmortality of fish, but
those fed the dietsupplemented with GroBiotic®-A hadreduced
mortality compared to fish fedthe basal diet.
SummaryResearch to date has shown that
dietary supplementation of the prebioticGroBiotic®-A has
consistently enhancedresistance to various pathogens byseveral fish
species including hybrid
-
striped bass, red drum, rainbow trout
and golden shiners.
In addition, improvements in feed
efficiency, nutrient digestibility and
several different non-specific immune
responses also have been observed with
the supplementation of this prebiotic to
practical diets.
Thus, the combination of improved
growth performance and survival of fish
fed this prebiotic may result in considerably
augmented productivity in various
aquacultural enterprises resulting in a
beneficial return on investment.
References:Buentello, JA. Neill, W.H .• and D.M. Gatlin.III.
(2008) Effects of dietary prebioticson growth. feed efficiency and
non-specific immunity of juvenile red drumSciaenops ocellatus fed
soybean-based diets.Aquaculture Research. In press.
Burr;G..M. Hurne, S.Rickeand D.M. GatlinIII (2008a) A
preliminary in vitro assessmentof Grobiotic®-A. brewers yeast and
fructo-oligosaccharide as prebiotics for the red drumSciaenops
ocellat~s. J.Environ.Sci.Health. B 43:253-260.
Burr;G..M. Horne,W H. Neill. and D. M. GatlinIII (2008b)
Effectsof prebiotics on nutrientdigestibility of a
soybean-meal-baseddiet by reddrum Sciaenops ocellatusi. Aquaculture
ResearchIn press.
Chinabut S..LimsuwanC. and Chanratchakool.P(1990)
Mycobacteriosisin the snakehead,Channastriatus
(Fowler).JoumalofFish Disease13.531-535.
Gatlin D. M. III.(2002) Nutrition and fish health.
In:FishNutrition (ed. by J.E.Halver and R.W Hardy).pp. 67
1-702.Academic Press.SanDiego. CA. USA
Gibson G. R.and Roberfroid M. B. (1995) Dietarymodulation of the
human colonic microbiota:introducing the concept of prebiotics.
Journal ofNutrition 125. 1401-1412.
Li Pand Gatlin D. M. III (2004) Dietary brewersyeast and the
prebiotic Grobiotic TMAE infiuencegrowth performance. Immune
responsesandresistanceof hybrid striped bass(Marone chrysopsx M.
saxadlis) to Streptococcus imae infection.Aquaculture
231.445-456.
Li Pand Gatlin D. M. III (2005). Evaluation of theprebiotic
GroBiotic®-A and brewers yeast asdietary supplements for sub-adult
hybrid stripedbass(Marone chrysops _ M. saxadlis) challengedin situ
with Mycobacterium marinum. Aquaculture.248.197-205.
Patterson J.A and Burkholder K M. (2003)Application of
prebiotics and probiotics in poultry
Sealey,W M..FT Barrows.K.A Johansen.K.OverturfS.E.LaPatraand
R.WHardy (2007) Evaluationof the ability of partiallyautolyzed
yeast and GroBiotic-A to improvediseaseresistance in rainbow trout.
NorthAmerican Journal of Aquaculture 69. 400-406.
production. PoultryScience 82. 627-631.
Plumb J. A (1997)Infectious diseasesofstriped
bass.In:StripedBassand Other MoroneCulture (ed. by R.M.Harrell).
pp. 271-313.Elsevier.Amsterdam.Netherlands.
Pre 10 c
4540
it 35-30~25~ 20o 15" to
5o
Cumulative Mortality of GoldenShiners Exposed to
Flavobacterium
columnare
------- ~ J-....,4%fat 10% fat 10%fat +
GroBiotic-ABacterial challengeby immersion atter16 wk
feedingDiet
Sink at al. (2007) N. Am. J. Aquaeult. 69:305·308
Sink,T D. and R.T Lochmann (2008) Preliminaryobservation of
mortality reduction in stressed.Flavobacterium columnare -
challengedgoldenshiners after treatment with a
dairy-yeastprebiotic. North American Journal of Aquaculture70.
192-194.
SinkT D..R.T Lochmann.AE.Goodwn andE.Marecaux(2007)Mortality
ratesin goldenshinersfedhigh-fatdietswith andwithouta
dairy-yeastprebioticbeforechallengewithR(N()bocteriumcolumnae.North
AmericanJoumalof Aquaculture69.305-308.
SzilagyiA (2002)Lactose- a potentialprebiotic.
AlimentaryPharmacology andTherapeutics 16.1591-1602.
Teitelbaum J.E.andWalkerWA (2002)Nutrtional impact ofpre-and
probioticsas protectivegastrointestinalorganisms.AnnualReview of
Nutrition22. 107-138.
vvhite L.A. NewmanM. c.. Cromwell G.L.and Lindemann M.D. (2002)
Brewersdried yeast as asource of mannanoligosaccharidesforweanling
pigs.Journalof Animal Science80.2619-2628.
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November-December081 INTERNATIONALAQUAFEED 121