ENSILING CHARACTERISTICS, DIGESTIBILITY ANDPALATABILITY OF TROPICAL GRASSES AS AFFECTED BY GROWTH STAGE, CHOPPING LENGTH AND ADDITIVES by Sujatha Panditharatne Dissertation submitted to the Graduate Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Animal Science (Forage Management and Utilization) APPROVED: J. H. Fontenot, Co-chairman V. G. Allen, Co-chairman R. E. Blaser M. c. N. ~ayasuriya K. E. Webb, Jr. L.A. Swiger, Department Head December, 1984 Blacksburg, Virginia
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ENSILING CHARACTERISTICS, DIGESTIBILITY AND PALATABILITY OF TROPICAL GRASSES AS AFFECTED BY GROWTH
STAGE, CHOPPING LENGTH AND ADDITIVES
by
Sujatha Panditharatne
Dissertation submitted to the Graduate Faculty of the Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy
in
Animal Science (Forage Management and Utilization)
APPROVED:
J. H. Fontenot, Co-chairman V. G. Allen, Co-chairman
R. E. Blaser
M. c. N. ~ayasuriya
K. E. Webb, Jr.
L.A. Swiger, Department Head
December, 1984
Blacksburg, Virginia
ACIC)JOWLEDGEMENTS
The author wishes to express her sincere thanks to all
individuals for their assistance and encouragement
throughout this study and her entire graduate program.
To the members of her graduate committee, Dr. J. P.
Fontenot, Dr. V. G. Allen, Dr. R.E. Blaser, Dr. K. E. Webb,
Jr., Dr. M. C. N. Jayasuriya and Dr. L. A. Swiger, the
author expresses her appreciation for their assistance.
The . .... ass1.s1..ance, guidance, patience and understanding
Dr. J. P. Fontenot has extended throughout this study is
especially appreciated. The encouragement~ guidance and
patience of Dr. V. G. Allen in conducting this study is also
appreciated. Special thanks are extended to Dr. M. C. N.
Jayasuriya, to whom the author is indebted for his technical
assistance, patience and counselling.
The author wishes to extend her special thanks to Mr.
Hugh Chester-Jones for many hours of assistance. Special
thanks are expres3ed to Professor A. S. B. Rajaguru and his
staff at Mawela Farm, Univer3ity of Peradeniya, Peradeniya,
Sri Lanka for many hours of 21.ssi sta:i.ce. Thar.ks are al so
extended to Miss Sandya Illep2ruma for her technical
assistance throughout the study.
Appreciation is expressed to the consortium for
International Agricultural Eo.ucation Development for the
scholarship awarded to the autl1cr, which made this study
ii
possible.
The author wishes to extend her sincere thanks to Miss
Laura Coater and Mrs. E. Stephens for their patience and
effort in typing this manuscript.
Finally, the author wishes to
appreciation to her parents and family,
moral support throughout this project.
convey her
for their
warmest
love and
The author lovingly
dedicates this dissertation to her parents.
iii
TABLE OF CONTENTS
ACKNOWLEDGEMENTS •
LIST OF TABLES ••
LIST OF FIGURES ••
CHAPTER I. INTRODUCTION ••
CHAPTER II. REVIEW OF LITERATURE.
Guinea Grass. • • • • . • . . Effect of Cutting Frequency on Yield Effect of Cutting Frequency on Composition Digesti~ility of Guinea Grass.
TABLE 5, COMPOSITION OF PRE-ENSILED MIXTURES OF GUINEA-'A' AND NB-21 AS AFFECTED BY ADDITIVES, SMALL SILO STUDYa
Additive Cassava Coconut Formic
Grass Component None tuber meal oil meal acid
Gui.nea-'A' Dry matter, %b,c 17.7 20.6 21. 2 18.8 C d e Crude protein,% ' ' 13.9 13.4 15.5 ]2,6
NB-21 Dry matter,% C ]6,3 18.4 ]8,4 16.0
Crude protein, %d,e 18.1 17.8 19.6 18.3
a Averaged over growth periods.
bNone vs additives (P < .01) for Guinea-'A'.
cFormic acid vs cassava tuber meal and coconut oil meal (P < .01) for Guinea-'A' and NB-21. d Dry basis.
eCassava tuber meal vs coconut oil meal (P < • 01) for Guinea-' A'.
SE
.54
.54
-"' w .48
.52
44
(P<.01) for forages cut after 2-wk growth, but was increased
in the forage after 3-wk growth for Guinea-'A' and NB-21,
however, the differences were small (table 6). Lengthened
growth period linearly increased (P<.01) the water-soluble
carbohydrate content of the pre-ensiled Guinea-'A' and NB-21
mixtures. Ensiling decreased the water-soluble carbohydrate
content of the post-ensiled mixtures of Guinea-'A' and NB-21
almost by one half or more. There were no significant
differences in water-soluble carbohydrate content among the
three growth periods of NB-21. Amount of lactic acid
present in post-ensiled mixtures was highest for 1 wk growth
for Guinea-' A' and lowest for 3 wk. Growth period had a
linear effect (P<.01) on lactic acid content of Guinea-'A'.
Fermentation characteristics of pre- and post-ensiled
mixtures as affected by additives are presented in table 7.
Addition of formic acid decreased (P<.01) the initial pH to
4.5 and 4.2 in Guinea-'A' and NB-21, respectively. The pH
of the material decreased by one or more uni ts in all
treatments following ensiling, except for formic acid
treated silage. Addition of cassava tuber meal and coconut
oil meal had a more pronounced effect in decreasing the pH
of the post-ensiled material than formic acid. Addition of
cassava tuber meal decreased ( P<. 01) the pH of the post-
ensi led material more than coconut oil meal.
Water-soluble carbohydrate content of pre-ensiled
TABLE 6. FERMENTATION CHARACTERISTICS OF PKE- AND l'OST-ENSILED MIXTURES OF GUINEA-'A' AND NB-21 AS AFFECTED BY STAGE OF GROWTH,
SMALL SILO STUDY a ·
Growth period, wk,
Item 1
pH Pre-ens ile<l b 6.2 Post-ensile<lc,d 5.0
Water-solublebctrbohydrates, %e 5.6 Pre-ensiled b
Post-ensiled 3.1
L . "d % e actic ac1 , " Post-e11siled h 2.5
a Averaged over additives.
bLinear effect (P < .01) for Guinea-'A'. c Quadratic ef feet (P < . 01) for Guinea-' A' • dQuadratic effect (P <.01) for NB-21. e Dry basis. fLinear effect (P < .01) for NB-21.
Guinea-'A' 2 3 SE
6.0 5.9 .09 4.8 4.9 .02
9.1 10.0 • 72 3.9 4.5 .20
1.8 1.5 .13
Growth period, wk, NB-21 -1 2 3
5.9 5.8 5.9 4.9 ,, .8 5.1
11.8 12.2 14.4 5.2 4.9 4.5
3.0 3.1 2.7
SE
.04
.05 p. VI
.50
.42
.29
TABLE 7. FERMENTATION CHARACTERISTICS OF PRE- AND POST-ENSILED MIXTURES OF GUINEA-'A' AND NB-21 AS AFFECTED BY ADDITIVES, SMALL SILO STUDYa
Control vs additives (P< .01) for Guinea-'A' and NB-21. ~Formic acid vs cassava tuber meal and coconut oil meal (P< .01) for Guinea-'A' and NB-21. 'Cassava tuber meal vs coconut oil meal (P < • 01) for Guinea-' A' and NB-21. ;Dry basis.
Formic acid vs cassava tuber meal and coconut oil meal (P < • 05) for Guinea-' A'. gCassava tuber meal vs coconut oil meal (P < .05) for Guinea-'A'.
SE
.11
.03
.83
.23
.15
.05
.06
.58
.47
. 35
"' °'
47
mixtures were increased (P<.01) with the addition of
additives ( table 7) . The effect was especially prominent
with the addition of cassava tuber meal. Cassava tuber meal
is a source of energy with a nitrogen-free extract content
of about 90% ( Oke, 1978) which consists of 80% starch and
20% sugars (Vogt, 1966). According to the analysis done in
this study, it had about 72% water-soluble carbohydrate
content (table 3). Coconut oil meal also increased (P<.01)
the water-soluble carbohydrate content of the pre-ensiled
mixture, when compared to the control ( table 7) . Water-
soluble carbohydrate content of post-ensiled mixtures were
less than half of the pre-ensiled mixtures (table 7). The
post-ensiled cassava tuber meal mixture contained the
highest water-soluble carbohydrate level.
Addition of cassava tuber meal resulted in the highest
post ensiled level of lactic acid for both grasses. The
higher lactic acid is probably due to the higher water-
soluble carbohydrate of that additive (table 3). The lactic
acid in formic acid treated silages was not increased,
compared to the control.
Coconut oil meal did not have a substantial effect on
lactic acid in Guinea-' A' silage ( table 7). Addition of
coconut oil meal markedly increased the lactic acid content
of the NB-21 silage, but, the effect was much less than
addition of cassava tuber meal.
48
Increasing length of the growth period linearly
increased (P<.01) the percentage dry matter in silages
( table 8). Lengthened growth period linearly decreased
( P<. 01) acetic acid of the Guinea-' A' silages. A similar
trend was observed for NB-21 silages but the effect was
quadratic (P<.01). This may be due to the better packing of
younger material in
fermentation.
the . 1 Sl.-0, thereby enhancing
Table 9 presents the effects of various additives upon
dry matter percentage and VFA concentration in the small
silos.
matter
Additives increased (P<.01) the percentage dry
of silage. However, formic acid did not
substantially change dry matter, compared to control.
Increased lactic acid was involved with lower acetic acid in
silage (table 9). In control and . formic acid treatments,
fermentation of forages produced mainly acetic acid and(or)
propionic acid, and not lactic acid as in the case of most
temperate silages.
As shown in table 10, dry matter content of the grass
used in the chopping length study was 19.8% and crude
protein was 12. 4%, dry basis. The pH of the post-ensiled
mixture was low, compared to pre-ensiled mixture (table 11).
Average post ensi led pH was lower ( P<. 05) for the silage
chopped to 1.5 cm vs 7.5 and 15 cm. A higher (P<.01) water-
soluble carbohydrate content of post-ensiled material was
TABLE 8. EFFECT OF PERIOD OF GROWTH OF GUINEA-'A' AND NB-21 UPON DRY MATTER CONTENT AND VOLATILE FATTY ACID PRODUCTION, SMALL SILOa
aAveraged over additives. hLinear effect (P < .01) for Guinea-'A'. cLinear effect (P < • 01) for NB-21. dory basis. eQuadratic effect (P < .05) for NB-21.
3 SE
17.99 .22
4.03 .26 2.78 .40 1.16 .21
.86 .24
.13 .07
.56 .09
Growth period, wk2 NB-21 1 2 3
12.89 14.59 15.32
5.56 4. 72 4.28 3.90 2.90 2.24
.83 .97 .99
.38 .82 .49 0 .21 .18
.35 . 51 .14
SE
.17
.42
.75
. 38 .i:-
.32 ,o
.07
. ] 4
TABLE 9. EFFECT OF ENSILING VARIOUS ADDITIVES UPON DRY MATTER CONTENT AND VOLATILE FATTY ACID CONCENTRATION, SMALL SILO STUUYd
Grass
Guinea-'A'
NB-21
I tern
Dry matter, %b,c
Volatile fatty acids, %d Aceticb,e Propionic c,e Isobutyri.c b ,c Butyricb,e Isovaleric b, c Valerich,c
Dry matter, %b,c,e
Volatile fatty acids, %d Aceticc Propionic c Isobutyric c Butyric Isovalericb Valericc
None
14.93
5.39 3.03 1.90 1.51
.48 1.09
12.10
5.28 3.93 1.26 1.23
.38
.81
Additives Cassava
tuber meal
19.31
3.49 .98 .11
0 0 0
16.22
3.40 .54 .19 .01
0 0
Cocortut oil meal
19.02
4.62 2.91
.56 1.40
.12
.10
17.09
3.45 1.84
,07 .18 .03 .02
aAveraged over growth periods. b Control vs additives (P < • 01) for Guinea-' A' and NB-21.
Formic acid
15. 77
4.69 3.40 1.25
.83
.29 1.13
11.67
7.30 5.70 2.20
.85
.12
. 53
cFormic acid vs cassava tuber meal and coconut oil meal (P < .01) for Guinea-' A' and NB-21. dory basis. eCassava tuber meal vs coconut oil meal (P < • 01) for Guinea-' A' and 1m-21.
SE
.25
.30 , l+6
.24
.28
.08
. 11
.20
.so
.89
.45
.39
.09
.17
\Jl 0
51
TABLE 10. COMPOSITION OF INITIAL SAMPLES OF GUINEA-'A' GRASS USED IN CHOPPING
matter basis. However, in this study, pH value of silages
ranged from 4.8 to 5.9, lactic acid concentrations of .05 to
2.9%, acetic acid concentration of 2.64 to 5.99% and butyric
acid concentration of .31 to 6.59% were observed, except in
addition of cassava tuber meal. When cassava tuber meal was
added those values were 4. 2, 7. O~~' 3. 4% and . 007% for pH,
lactic acid, acetic acid and butyric acid, respectively. It
is noteworthy, that in silages with added cassava tuber
meal, fermentation of forages was mainly due to lactic acid,
as in most temperate forage silages. In all the other
treatments, fermentation of forages was mainly due to acetic
acid and (or) propionic acid but, not due to the lactic
acid. According to the standard values mentioned above, all
silages except that with the addition of cassava tuber meal
treatment would be classified as poor quality silages.
Several workers have shown that the fermentation
pathway of tropical forage silages was different from
temperate forage silages (Miller et al., 1966; Catchpoole,
1968; Catchpoole and Williams, 1969; Catchpoole and Henzell,
1971; Tosi, 1973; Aguilera, 1975; Xande, 1978). According
to these workers, the factors responsible for preservation
of tropical forage, silages are not
have concluded that this process is
production of high concentration of
known. However, they
not related with the
lactic acid. Several
workers have suggested that acetic acid rather than lactic
63
acid is the main preservative in tropical forage silages
(Catchpoole, 1968; Catchpoole and Williams, 1969; Catchpoole
and Henzell, 1971; Tosi, 1973; Aguilera, 1975; Xande, 1978).
Silages made in this study had more acetic than lactic
acid, except when cassava tuber meal was added. It appears
that conservation of silages was not due to lactic acid but
may have been due to acetic acid. Addition of cassava tuber
meal in the mixture followed the normal procedure for
temperate forage silages and produced lactic acid
fermentation. Several workers have shown that formic acid
could inhibit undesirable fermentation in silage made from
temperate grasses (McDonald, 1981). However, addition of 3%
formic acid had no significant effect, compared to control
silages.
64
Literature Cited
R. 1975. Dynamics grass silage. 1. without additives.
Aguilera, G. tropical purpureum) 9(2):227.
of the fermentation of Elephant grass ( P.
Cuban J. of Agric. Sci.
A.O.A.C. 1980. Official Methods of Analysis ( 12th Ed. ) . Association of Official Analytical Chemists. Washington, D.C.
Anderson, R. 1982. Effect of stage of maturity and chop length on the chemical composition and utilization of formic acid-treated ryegrass and formic acid silage by sheep. Grass and Forage Sci. 27:139.
Barker, S. B. and W. H. Summerson. determination of lactic d.Cid J. Biol. Chem. 138:535.
1941. The colorimetric in biological material.
Carpintero, M. C., A. J. Fermentation studies 20:677.
Holding and P. McDonald. 1969. on lucerne J. Sci. Food Agr.
Catchpoole, V. R. 1965. Laboratory ensilage of sphacelata (Nandi) and Chloris gayana (C.P.I. Australian J. Agr. Res. 16:391.
Setaria 16144) .
Catchpoole, V. R; 1966. Laboratory sphacelata (Nandi) with molasses. Agr. Anim. Husb. 6:76.
ensilage of Setaria Australian J. Exp.
Catchpoole, V. R. 1968. Effect rate of nitrogen fertilizer sphacilata. Australian J. 8:569.
of season, maturity and on ensilage of Setaria Exp. Agr. Anim. Husb.
Catchpoole, V. R. and E. F. Henzell. 1971. Silage and silage making from tropical herbage species. Herbage Abstr. 41:213.
65
Catchpoole, V. R. and N. T. Williams. 1969. pattern of silage fermentation in two grasses. J. Brit. Grassland Soc. 24:317.
The general subtropical
Dubois, M., K. A. Gilles, J. K. Hamilton, P. A. Rebers and F. Smith. 1956. Colorimetric method for determination of sugars and related substances. Anal. Chem. 28:350.
Erwin, E. S., G. J. Marco and E. M. Emery. 1961. Volatile fatty acid analyses of blood and rumen fluid by gas chromatography. J. Dairy Sci. 44:1768.
Goonewardene, L.A. and R. R. Appadurai. 1971. Changes in feeding value with growth in three important fodder grasses of Ceylon. Trop. Agriculturist 127(3 and 4):145.
Johnson, R. R., T. L. Balwani, L. H. Johnson K. E. McClure and B. A. Dehority. 1966. Corn plant maturity. II. Effect on in vitro cellulose digestibility and soluble carbohydrate content. J. Anim. Sci. 25:617.
Markham, R. 1942. A steam distillation apparatus suitable for micro-Kjeldahl analysis. Biochem. J. 36:790.
McDonald, P. 1981. The Biochemistry of Silage. and Sons. New York.
John Wiley
Miller, W. J., C. M. Clifton and N. W. Cameron. 1963. Ensiling characteristics of coastal Bermudagrass harvested at the pre-head and full-head stages of growth. J. Dairy Sci. 46:727.
Miller, W. J., Cameron. Sudangrass 49:477.
C. M. Clifton, P. R. Fowler and 1966. Ensiling characteristics of and Coastal Bermudagrass. J. Dairy
N. W. Tift Sci.
Oakes, A. J. 1966. Ef feet of nitrogen fertilization and harvest frequency on yield and composition of Panicum
66
maximum, Jacq. in dry tropics. Agron. J. 58:75.
Oke, 0. L. 1978. feed. Anim.
Problems in the use of cassava as animal Feed. Sci. Tech. 3:345.
Oyenuga, V. A. 1960. Effect of stage of growth and frequency of cutting on the yield and chemical composition of some Nigerian fodder grasses - Panicum maximum Jacq. J. Agr. Sci. {Cambridge) 55:339.
Pennington, R. J. and T. M. Sutherland. 1956. production from various substrates by epithelium. Biochem. J. 63:353.
Ketone-body sheep-rumen
SAS. 1982. SAS User's Guide. Statistical Analysis System Institute Inc., Cary, NC.
Thomas, P. C., N. C. Kelly and M. K. Wait. effect of physical form of a silage on its consumption and digestibility by sheep. Grassland Soc. 31:19.
1976. The voluntary J. Brit.
Tosi, H. 1973. Ensilage differentes tratamentos. Sao Paulo - Brazil.
de Gramineas tropicais sob Ph.D. Dissertation, Estado de
Van Soest, P. J. 1963. The use of analysis of fibrous feeds: I I. determination of fiber and lignin. Agr. Chem. 48:829.
detergents in the A rapid method for
J. Assoc. Official
Van Soest, P. J. and R. H. Wine. 1967. Use of detergents in the analysis of fibrous feeds. IV. The determination of plant cell wall constituents. J. Assoc. Official Anal. Chem. 50:50.
Van Soest, P. J. and R. H. Wine. 1968. Determination of lignin and cellulose in acid-detergent fiber with permanganate. J. Assoc. Official Anal. Chem. 51:780.
67
Vicente-Chandler, J., S. Silva and J. Figarella. 1959. The effect of nitrogen fertilization and frequency of cutting on the yield and composition of three tropical grasses. Agron. J. 51:202.
Vogt, H. 1966. The use of tapioca meal in poultry rations. World Poultry Sci. J. 22:113.
Xande, A. 1978. L'ensilage d'herb, une technique de conservation d l'herbe permettant de pallier au deficit alimentaire des ruminants durant la periode du careme. 1. Aspects theorique et pratique particulari te des fourrage. (Ensilage of grass, a conservation technique for obviating the food shortage of ruminants during the dry season. 1. Theoretical and practical aspects -particularities of tropical forages.) J. Nouvelles Agronomiques des Antilles et de la_Guyane 4(2):63 (Via Herbage Abstr. 51(2):62, 1981).
CHAPTER IV JOURNAL ARTICLE II
EFFECT OF STAGE OF GROWTH AND CHOPPING LENGTH ON DIGESTIBILITY AND PALATABILITY OF GUINEA-'A' GRASS
Experiments were
Summary
conducted to investigate the
digestibility and palatability of Guinea-'A' grass silage by
sheep. Two- and 3-wk growth of Guinea-'A' grass was
harvested and ensiled chopped or unchopped in 210 liter
metal drums. Animals averaging 20 kg initially were used,
and feces were collected by means of light harness and
canvas bag. Apparent digestibility of dry matter, crude
protein, neutral detergent fiber (NDF) and acid detergent
fiber (ADF) were higher (P<. 01) for 2-wk, compared to the
3-wk growth. Chopping the grass before ensiling increased
( P<. 01) the apparent digestibility of dry matter, crude
protein, NDF, ADF and hemicellulose by sheep. In the
palatability trial, no significant differences were observed
for dry matter intake by sheep due to growth stage.
However, chopping increased ( P<. 01) dry matter intake by
sheep by almost 17%. The effect of chopping on increasing
silage intake by sheep may be associated with the better
Lignin 37.2 38.7 32.8 35.1 1.6 --a b 2-wk vs 3-wk (P < .01).
Unchopped vs chopped (P < .01). cGrowth period x chopping (P < • 01).
76
ratio and high fiber in those forages. Leaf to stem ratios
were 1.98 and 1.22 whereas plant heights were 72 cm and 86
cm for 2- and 3-wk growth Guinea grass, respectively.
Chopping increased ( P<. 01) the apparent digestibility
of dry matter, CP, NDF, ADF and hemicellulose by sheep
(table 19). Dulphy and Demarquilly (1973) have found a
negative correlation between increasing chop length and
fermentation quality in temperate grass silage. According
to their results, the main advantage of short chop length
would appear to lie in the possibility of more efficient
compaction of the ensiled material and the release of
fermentable substrates for fermentation by microorganisms.
They noted that while fermentation quality differed with
chopping length, there were no significant differences in
the digestibility coefficients of different length temperate
forage silages offered to sheep. In trials with steers and
cows Balch et al. (1955) and Murdock (1965) found that
chopping increased the digestibility of the temperate forage
silage. Thomas et al. (1976) found that the digestibility
was unchanged for chopped temperate forage silage, but
significantly reduced for minced silage by sheep. On the
contrary, Grant et al. (1974) reported that chopping
increased the apparent and true digestibilities of dry
matter of Napier grass during wet season in Philippines.
Devendra ( 1977) also reported that chopping increased the
77
digestibility of nutrients of Guinea grass compared to long
forage.
was
Interaction between growth
observed for apparent
stage and chopping length
digestibility of CP.
Digestibility of CP increased more at 3-wk than 2-wk growth
due to chopping forage.
Palatability. No significant differences were observed
for dry matter intake of silage by sheep due to the growth
stage (table 20). Chopping increased (P<.01) the dry matter
intake by sheep by almost 17% ( table 20). The effect of
chopping on increasing feed intake by sheep may be
associated with the better fermentation of the chopped
forage. It may also be possible that the effective
breakdown with long silage was delayed, thus, the mean
retention time in the reticule-rumen of the undigestible
fraction would be longer and cause a lower level of
voluntary feed intake. Several workers have reported that
chopping had a significant beneficial effect on feed intake
during the dry season (Grant et al., 1974; Devendra, 1977).
According to Devendra (1977) the higher intake of dry matter
in chopped Guinea-'A'
the diet, compared
grass was due to the physical form of
to unchopped forages. Moore (1964)
stated that the effects of grinding and pelleting on forage
utilization are due to increased rate of passage, decreased
digestibility, increased rate of intake, decreased
TABLE 20. DRY MATTER INTAKE OF SHEEP FED GUINEA-'A' SILAGE
Growth period, wk 2
Item Unchopped Chopped Unchopped
Grams per day a 425 513 410
G w.75 d a rams per kg per ay 44.9 51.6 42.9
a Unchopped vs chopped (P < .01).
3 Chopped
540
53.4
SE
24.3
2.2
....... CX>
79
rumination and change in some physiological conditions in
the rumen. In particular, they reported that processing
helps the breakdown of the structural components of the
grass so that the structural inhibition of intake is reduced
and the grass is more accessible to the digestive processes.
Between chopping and pelleting, chopping is probably the
more common, and maximum benefits appears to be associated
with this method.
The intake data obtained from the palatability trial
(table 20) support the well documented conclusion that short
chopping of forages improves the intake of silage by sheep
(Dulphy and Demarquilly, 1973; Dulphy and Michalet, 1975;
Thomas et al., 1976; Deswysen et al., 1978; Anderson, 1982).
Several workers have reported that this increased intake is
associated with an improvement in the fermentation
characteristics of short chopped silage (Murdoch et al.,
1955; Balch et al., 1955; Murdoch, 1965; Dulphy and
Demarquilly, 1973; Deswysen et al., 1978; Anderson, 1982).
However, no significant effect of stage of maturity on
intake of Guinea 'A' silage (table 20) was observed. This
seems surprising in view of the effect of stage of maturity
on the fermentation quality of silage. However, Anderson
( 1982) has shown that there was no significant effect of
stage of maturity on silage intake by sheep.
In conclusion, the results presented here indicate that
80
the stage of maturity of the forages significantly affect
the digestibility of silages but had no effect on the
voluntary feed intake. Furthermore, chopping the forages
before ensiling increased the digestibility as well as the
feed intake of silage by sheep. The data indicate that
stage of growth influences digestibility and particle size
of forages is a prime factor influencing intake and
digestibility in sheep.
81
Literature cited
Anderson, R. 1982. Effect of stage of maturity and chop length on the chemical composition and utilization of formic acid-treated ryegrass and formic acid silage by sheep. Grass and Forage Sci. 27:139.
A.O.A.C. 1980. Official Methods of Analysis (12th Ed.). Association of Official Analytical Chemists. Washington, D.C.
Balch, C. C., J. C. Murdoch and J. Turner. 1955. The effect of chopping and lacerating before ensiling on the digestibility of silage by cows and steers. J. of the Brit. Grassland Soc. 10:326.
Catchpoole, V. R. 1965. Laboratory ensilage of sphacelata (Nandi) and Chloris gayana (C.P.I. Australian J. Agr. Res. 16:391.
Setaria 16144).
Catchpoole, V. R. 1966. Laboratory ensilage of Setaria sphacelata (Nandi) with molasses. Australian J. Exp. Agr. Anim. Husb. 6:76.
Catchpoole, V. R. 1968. Effect rate of nitrogen fertilizer sphacilata. Australian J. 8:569.
of season, maturity and on ensilage of Setaria Exp. Agr. Anim. Husb.
Catchpoole, V. R. and E. F. Henzell. 1971. Silage and silage making from tropical herbage species. Herbage Abstr. 41:213.
Catchpoole, V. R. and N. T. Williams. 1969. pattern of silage fermentation in two grasses. J. Brit. Grassland Soc. 24:317.
The general subtropical
Deswysen, A., M. Vanbelle and M. Focant. 1978. The effect of silage chop length on the voluntary intake and rumination behaviour of sheep. J. Brit. Grassland Soc. 33:107.
82
Devendra, C. 1977. Studies in the intake and digestibility of two varieties (Serdang and Coloniao) of Guinea grass (Panicum maximum) by goats and sheep. Mardi Res. Bull. 5(2):110.
Dulphy, J. P. and C. Demarqui lly. 1973. Influence de la machine de recolte et de la finesse de hachage sur la valeur alimentaire des ensilage. (Influence of harvesting machine and chop length on the alimentary value of silage.) Ann. Zootechnie 22:199.
Dulphy, J. P. and B. Michalet. 1975. Influence comparee de la machine de recolte sur le quantities d'ensilage ingerees par de genisses et des moutons. (Comparative effect of harvesting machine on silage intake by heifers and sheep.) Ann. Zootechnie 24:757.
Fontenot, J. P. and H. A. Hopkins. physical form of different parts rations of feedlot performance and Anim. Sci. 24(1):62.
1965. Effect of of lamb fattening digestibility. J.
Grant, R. J., P. J. Vansoest, R. E. McDowell and C. B. Perez, Jr. 1974. Intake, digestibility and metabolic loss of Napier grass by cattle and buffaloes when fed wilted, chopped and whole. J. Anim. Sci. 39(2):423.
Miller, W. J., C. M. Clifton and N. W. Cameron. 1963. Ensiling characteristics of coastal Bermudagrass harvested at the pre-head and full-head stages of growth. J. Dairy Sci. 46:727.
Miller, W. J., Cameron. Sudangrass 49:477.
C. M. Clifton, P. R. Fowler and N. W. 1966. Ensiling characteristics of Tift and Coastal Bermudagrass. J. Dairy Sci.
Moore, J. A. 1964. Symposium on forage utilization: Nutritive value of forage as affected by physicalform. 1. General principles involved with ruminants and effect of feeding pelleted or wafered forage to dairy
83
cattle. J. Anim. Sci. 23:230.
Murdoch, J. C. 1965. The effect of length of silage on its voluntary intake by cattle. J. Brit. Grassland Soc. 20: 54.
Murdoch, J. C., D. A. Balch, M. C. Holdsworth and M. Wood. 1955. The effect of chopping, lacerating and wi 1 ting of herbage on the chamical composition of silage. J. Brit. Grassland Soc. 10:181.
SAS. 1982. SAS User's Guide. Statistical Analysis System Institute Inc., Cary, NC.
Thomas, P. C., N. C. Kelly and· M. K. Wait. effect of physical form of a silage on its consumption and digestibility by sheep. Grassland Soc. 31:19.
1976. The voluntary J. Brit.
Tosi, H. 1972. Efei to da adicao de ni vei s crescentes de melaco na ensilagem do capim elefante (Penniseturn purpureurn, Schum) variedade. Napier. M.S. Thesis. Estado de Sao Paulo - Brazil.
Van Soest, P. J. 1963. The use of analysis of fibrous feeds: I I. determination of fiber and lignin. Agr. Chern. 48:829.
detergents in the A rapid method for
J. Assoc. Official
Van Soest, P. J. and R. H. Wine. 1967. Use of detergents in the analysis of fibrous feeds. IV. The determination of plant cell wall constituents. J. Assoc. Official Anal. Chern. 50:50.
Van Soest, P. J. and R. H. Wine. 1968. Determination of lignin and cellulose in acid-detergent fiber with permanganate. J. Assoc. Official Anal. Chern. 51:780.
Xande, A. 1978. L'ensilage d'herb, une technique de conservation d l'herbe permettant de pallier au deficit alimentaire des ruminants durant la periode du carerne.
84
1. Aspects theorique et pratique - particularite des fourrage. (Ensilage of grass, a conservation technique for obviating the food shortage of ruminants during the dry season. 1. Theoretical and practical aspects -particularities of tropical forages.) J. Nouvelles Agronomiques des Antilles et de la Guyane 4(2):63 (Via Herbage Abstr. 51(2):62, 1981).
CHAPTER V EFFECT OF CUTTING FREQUENCY ON YIELD OF GUINEA-'A'
(PANICUM MAXIMUM) AND NB-21 (PENNISETUM PURPUREUM X PENNISETUM AMERICANUM)
FODDERS IN SRI LANKA
Summary
Research was undertaken in Sri Lanka to study the
effect of cutting frequency on yield of Guinea-'A' and NB-21
grasses. All plots were cut uniformly to a height of 12.5
cm from ground level prior to the commencement of the trial.
Plots were harvested l, 2 and 3 wk after new foliage emerged
and yields were recorded. Plots were arranged in a
randomized block design with three replications, harvested
twice more at 30-d intervals and regrowth measurements were
taken. Lengthening the cutting interval resulted in linear
increase ( P<. 01) in the dry matter yield of both grasses.
It was also shown that the regrowth of Guinea-'A' and NB-21
were affected by the length of period of the previous
growth.
(Key Words: Frequency of Cutting, Yield, Guinea Grass,
NB-21, Regrowth)
Introduction
The main objective of pasture management is to secure
the highest output of animal products per hectare.
Intensive management involves the production of high yields
of high quality forage per hectare, while maintaining the
integrity of the sward. Several factors control and
85
86
contribute to high production of pastures. Frequency of
defoliation is a primary factor which governs the yield and
quality of forages.
Stored reserves are important for regrowth of perennial
grasses. The storage organs may be roots, rhizomes or the
bases of the stems. Defoliation which results in new top
growth decreases the plant stored reserves. Excessive
defoliation can result in a drastic reduction of herbage
yields both during and after the cutting treatment due. to
carbohydrate starvation (Appadurai, 1968). On the other
hand, as soon as adequate leaf areas are reached
p~otosynthesis begins and storage of carbohydrates will
occur.
The objective of this study was to study the effect of
cutting frequency on yield of Guinea-'A' and NB-21 grasses.
Materials and Methods
Dry Matter Yield. Two fodder grasses namely Guinea-'A'
and NB-21, established in 1980, were grown at the Mawela
Farm, Peradeniya (Longitude 80° 29'E, latitude 7° 13'N,
elevation 485m), Sri Lanka in a reddish brown latasolic soil
with pH values of 5. 8 for the Guinea-' A' and 4. 9 for the
NB-21 areas. Plots measuring 17. 4 x 2. 8 rn for Guinea-' A'
and 10 x 8.2 rn for NB-21 were arranged in a randomized block
design with three replications. Phosphorous (P) as triple
super-phosphate and N as urea were applied at the rate of
87
112 and 168.5 kg/ha, respectively, uniformly to the entire
area at the beginning of the trial in May, 1983. Guinea-'A'
plots were irrigated during the trial. Each forage was
harvested at three stages of plant growth, corresponding to
l, 2 and 3 wk after cutting the foliage. The grasses were
cut uniformly to a height of 12.5 cm from ground level, at 1
wk intervals, prior to the commencement of the trial so that
all plots were harvested on the same day for ensiling.
At each harvesting the herbage was cut to 12.5 cm from
ground level, as at commencement, and the forages from the
three replicates were collected and weighed separately. The
sub-samples taken were dried in an Unitherm oven at 55 C for
24 h and used for the determination of dry matter. The
remaining fresh material was used for ensiling in small
silos (Chapter III).
All plots were harvested again twice, at 30-d
intervals, and yield measurements were taken. Effects of
the three cutting frequencies on plant growth were measured
by measuring the plant height, and determining leaf to stem
ratio.
Statistical Analysis. Statistical analyses were
performed using the analysis of variance by the general
linear model procedure described by SAS (1982). Comparisons
were made to test linear and quadratic effects of stage of
growth.
88
Results and Discussion
Dry matter yields of Guinea-'A' and NB-21 as affected
by frequency of cutting are presented in table 21.
Lengthening the cutting interval resulted in a linear
increase (P<.01) in dry matter yield of both grasses. Dry
matter yield of Guinea-' A' was increased almost two- and
three-fold with 2- and 3-wk, compared to the 1-wk cutting
interval. This increase in yield with less frequent cutting
is in ~eneral agreement with previous research (Watkins and
Lewy, 1951; Vicente-Chandler et al., 1959; Oyenuga, 1960;
Goonewardene and Appadurai, 1971; Mani and Kothandaraman,
1980; Sanghi and Raj, 1983).
Table 22 presents the dry matter yield of Guinea-' A'
and NB-21 after two consecutive 30-d regrowth periods. It
is important to note that the regrowth on all treatments
occurred during the same time period and the ref ore, under
the same environmental conditions. The dry matter yield of
Guinea-' A' for the first 30 d tended to increase with the
length of period of previous growth. Dry matter yield
during the second 30 d regrowth was linearly increased
(P<.01) with the length of the initial growth periods. Poor
dry matter yield in 1 wk cut fodder may be associated with
the less available leaf area for photosynthesis and less
carbohydrate reserves in roots and stems. Dry matter yield
89
TABLE 21, DRY MATTER YIELD OF GUINEA-'A' AND NB-21 AS AFFECTED BY LENGTH OF GROWTH PERIOD
Grass 1 Growth period, wk
2 3
-1 -1 ------- kg•ha •cut -------
Guinea-'A'a
NB-2la
760
137
aLinear effect (P < .01).
1892
214
2449
274
SE
136
9
90
TABLE 22. REGROWTH DRY MATTER YIELD OF GUINEA-'A' AND NB-21 AS AFFECTED BY GROWTH PERIOD
Days of Previous growth 2eriod, wk Grass regrowth 1 2 3 SE
-1 -1 ------ kg•ha •cut
Guinea-'A' First 30 d 1285 1330 1611 340 Second 30 da 1801 2358 2849 56
NB-21 First 30 da 150 212 352 18 Second 30 da 371 452 661 43
~inear effect (P < .01).
91
for regrowth of NB-21, for both 30 d periods were linearly
increased with length of the initial growth periods.
There was no significant effect of frequency of cutting
on the plant height or leaf to stem ratio of regrowth of
Guinea-'A' and NB-21 (tables 23 and 24).
TABLE 23. LEAF TO STEM RATIO AND PLANT HEIGHTS OF GUINEA-'A' AS AFFECTED IlY GROWTH PERIOD
Days of Previous growth ~eriod, wk Item regrowth 1 2 3
Leaf/stem First 30 d 5.98 8.07 4.00
Second 30 d 2.44 2.44 2.61 '° N
Plant height, cm First 30 d 78 77 71
Second 30 d 92 92 9J
TABLE 2/•. LEAF TO STEM RATIO AND PLANT HEIGHTS OF NB-21 AS AFFECTED BY GROWTH PERIOD
Days of Previous growth eeriod! wk Item regrowth 1 2 3
Leaf/stem First 30 d 8.05 4.85 5.05
Second 30 d 2.25 2.09 2.54 \0 \.,)
Plant height, cm First 30 d 77 79 76
Second 30 d 94 94 92
94
Literature Cited
Appadurai, R. R. 1968. Grassland Farming in Ceylon. T.B.S. Godamunne and Sons Ltd., Kandy, Ceylon.
Goonewardene, L. A. and R. R. Appadurai. 1971. Changes in feeding value with growth in three important fodder grasses of Ceylon. Trop. Agriculturist 127(3 and 4):145.
Mani, A. K. and G. V. Kothandaraman. 1980. Influence of nitrogen and stages of cutting on the yield of hybrid napier grass varieties. Madras Agric. J. 67(12):797.
Omaliko, C. P. E. 1980. Influence of initial ~utting date and cutting frequency on yield and quality of star, elephant and Guinea grasses. Grass and Forage Sci. 35:139.
Oyenuga, V. A. 1960. Effect of stage of growth and frequency of cutting on the yield and chemical composition of some Nigerian fodder grasses - Panicurn maximum Jacq. J. Agr. Sci. (Cambridge) 55:339.
Sanghi, A. K. and M. F. Raj. 1983. Performance and phenotypic stability in pearlmillet and Napier hybrids. Indian J. Agr. Sci. 53(2):105.
SAS. 1982. SAS User's Guide. Statistical Analysis System Analysis, Inc., Cary, NC.
Vicente-Chandler, J., S. Silva and J. Figarella. 1959. The effect of nitrogen fertilization and frequency of cutting on the yield and composition of three tropical grasses. Agron. J. 51:202.
Watkins, J. W. and M. Lewy-Van Severin. 1951. Effect of frequency and height of cutting on the yield,, stand and protein content of some forages in El Salvador. Agron. J. 43(6):291.
GENERAL DISCUSSION
The rapid increase in costs and the shortage of
concentrate feeds in recent years have highlighted the
importance of herbage as a cheap source of food for farm
animals in Sri Lanka. Traditionally, forage for livestock
of low quality and was provided by indigenous grasses
nutritive value. In view of the poor performance of animals
in these natural grazing lands, improved varieties have been
developed.
the years
These improved varieties have been tried over
and recommendations for different agro-climatic
zones have been made.
The rainfall in Sri Lanka is seasonal, and as a result,
excess amounts
seasons, which
unavailability
quantity is a
of forages are
are not properly
of good quality
general problem
available in the rainy
utilized. However, the
forage in the required
and in absence of any
conserved forage, this problem becomes more serious during
the drier months when there is little or no growth of the
forage. Therefore, forage conservation could be used as an
insurance against the scarcity of feed during the dry
season.
Forage could be conserved either as hay or silage,
however, none of these practices are commonly practiced in
Sri Lanka. There are various advantages in making silage
over making hay. Hay making is a problem in Sri Lanka,
95
96
because the periods of maximum forage production coincide
with the periods of frequent rains. The effect of rain on
cut herbage results in loss of soluble carbohydrates and
other nutrients, and loss of dry matter by microbial
decomposition. Prolonged wet weather results in complete
loss of the material. High relative humidity is also a
problem in hay making which will permit the drying of grass
only to a certain moisture content and this may be too high
for safe storage of grass as hay. Therefore, silage making
appears to be more feasible than making of hay.
Silage making is not a common practice among livestock
farmers in Sri Lanka, however, on government farms, silage
has been made with varying success and with varying capital
outlay in towers, pits and trenches. However, information
about their fermentation characteristics, feeding value and
utilization is insufficient and often incomplete. The
objectives of the present study were, therefore, to obtain
information on the fermentation characteristics and feeding
value of two fodder grasses grown in the mid-country of Sri
Lanka for ruminants at various stages of growth and ensiled
with different additives.
Two fodder grasses, Guinea-'A' and NB-21 were harvested
at 1, 2 and 3 wk of growth, chopped and ensi led alone or
with, cassava tuber meal, coconut oil meal or formic acid.
In another study, Guinea-' A' grass was hand-chopped into
97
1.5, 7.5 and 15 cm and ensiled in small laboratory silos to
study the effect of chopping length on the ensiling
characteristics of the forage. In a third study, Guinea-'A'
grass was harvested at 2 and 3 wk of growth ensiled chopped
or unchopped in metal drums. Fermentation characteristics
of the ensiled material were studied and digestibility and
palatability trials were conducted to study the feeding
value of silages by sheep.
According to the results, the factors responsible for
preservation of these forages is not related with the high
production of high concentrations of lactic acid, as in
temperate forage silages. According to Langston et al.
(1958) as cited in Catcpoole and Henzell (1971), lactic acid
content in well preserved silage can be between 3 and 13% of
dry basis. However, in this study, pH values of silages
ranged from 4.8 to 5.9, lactic acid concentration of .05 to
2.9%, acetic acid concentration of 2.64 to 5.99% and butyric
acid concentration of .31 to 6.59% was observed, except in
addition of cassava tuber meal. In silage with addition of
cassava tuber meal, those values were 4. 2, 7%, 3. 4% and
.007% for pH, lactic, acetic and butyric acid, respectively.
The data shows that the .fermentation of forages was not due
to lactic acid but may have been due to acetic acid and (or)
propionic acid. These data are in agreement with the
previous work done with tropical forage silages (Miller et
98
al, 1966; Catchpoole, 1968; Catchpoole and Williams, 1969;
1975; Catchpoole and Henzell,
Xande, 1978). However,
1971; Tosi, 1973; Aguilera,
i~ forages with addition of cassava
tuber meal, fermentation of forages was mainly due to lactic
acid as in most temperate for age silages. Addition of 3%
formic acid had no significant effect over control silage
and followed the same type of fermentation as in the
control.
Chopping the grass into fine pieces before ensiling
increased the lactic and
butyric acid production.
digestibility and intake
acetic acid and decreased the
Chopping also increased the
of Guinea-'A' grass silage by
sheep. This may
the
be associated with the more efficient
and the release of
fermentation by
compaction of
fermentable
ensiled material
substrates for rapid
microorganisms. This is in agreement with previous work
(Murdoch et al., 1955;
Dulphy and Demarquilly,
1977; Deswysen et al. ,
Balch et al., 1955; Murdoch, 1965;
1974; Grant et al., 1974; Devendra,
1978; Anderson, 1982). However,
there was no significant effect of stage of maturity on
intake of Guinea-'A' silage. This is in agreement with
Anderson (1982), who has shown that there was no significant
effect of stage of maturity on silage intake by sheep.
According to the dry matter yield study, cutting the
grass at 3 wk growth stage is better than 1 and 2 wk and
99
resulted in a higher regrowth of forages. This higher yield
of 3 wk growth was associated with medium quality forages.
The low yields of NB-21 as compared to Guinea-' A' may be
attributed to moisture stress as Guinea-' A' was irrigated
during periods of low rainfall, whereas NB-21 was not
irrigated. Also frequent cuttings would be expected to
depress yields of NB-21 more than Guinea-' A', the former
being a tall and erect species which would have fewer leaves
after cutting and would require a longer period for
regrowth.
In conclusion, the results presenced here indicate that
the criteria of preservation quality for temperate grasses
do not apply for tropical grasses, because of a different
fermentation pathway. The fermentation of forages may have
been due to acetic acid and (or) propionic acid. Addition
of cassava tuber meal and coconut oil meal improved the
quality of the silage compared to the control. However, the
control silages had good aroma and good fermentation.
Although the silages of the two grasses may not be compared,
because of being different experiments, it may be concluded
that NB-21 produced the better silage. The soluble
carbohydrate, crude protein and lactic acid for a given
additive was higher for NB-21 than for Guinea-' A' .
NB-21 also produced a silage with the better aroma.
of maturity of the silages significantly affect
The
Stage
the
100
digestibility of silage but had no effect on the voluntary
feed intake. Chopping the forages before ensiling increased
the digestibility as well as the feed intake of silage by
sheep, however, the values obtained for intake and
digestibility of unchopped silages were good. The data
indicate that the tropical forages could be ensiled even
without additives or chopping when cut at proper stage of
growth, and obtain quality silage. However, it should be
noted that it may not be feasible to harvest very early
growth stage forage for continuous productivity of the
forages.
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Appadurai, R. R. 1968. Grassland Farming in Ceylon. T.B.S. Godamunne and Sons Ltd., Kandy, Ceylon.
Balch, C. C. , J. C. Murdoch and J. Turner. 1955. The effect of chopping and lacerating before ensiling on the digestibility of silage by cows and steers. J. Brit. Grassland Soc. 10:326.
Barker, S. B. and W. H. Summerson. determination of lactic acid J. Biol. Chem. 138:535.
1941. The colorimetric in biological material.
Barnett, A. J. G. 1954. Press, New York.
Carpintero, M. C., A. J. Fermentation studies 20:677.
Silage Fermentation. Academic
Holding and P. McDonald. 1969. on lucerne J. Sci. Food Agr.
Catchpoole, V. R. 1965. Laboratory ensilage of sphacelata (Nandi) and Chloris gayana (C.P.I. Australian J. Agr. Res. 16:391.
Setaria 16144).
Catchpoole, V. R. 1966. Laboratory ensilage of Setaria
101
102
sphacelata (Nandi) with molasses. Agr. Anim. Husb. 6:76.
Australian J. Exp.
Catchpoole, V. R. 1968. Effect rate of nitrogen fertilizer sphacilata. Australian J. 8:569.
of season, maturity and on ensilage of Setaria Exp. Agr. Anim. Husb.
Catchpoole, V. R. and E. F. Henzell. 1971. Silage and silage making from tropical herbage species. Herbage Abstr. 41:213.
Catchpoole, V. R. and N. T. Williams. 1969. pattern of silage fermentation in two grasses. J. Brit. Grassland Soc. 24:317.
The general subtropical
Chauhan, T. R. 1983. Effect of stage of maturity on nutritive value of hybrid Napier (NB-21) fodder (hay) in buffalo calves. Indian J. Anim. Sci. 53(4).
Cresswell, D. C. and C. C. Brooks. 1971a. Composition, apparent digestibiity and energy evaluation of coconut oil meal. J. Anim. Sci. 33:366.
Daftardar, S. Y. and G. K. Zende. 1968. Periodical changes in the protein contents of Gajraj grass. Poona Agric. Coll. Mag. 58(2-3):110.
Deswysen, A., M. Vanbelle and M. Focant. 1978. of silage chop length on the voluntary rumination behaviour of sheep. J. of Grassland Soc. 33:107.
The effect intake and the Brit.
Devendra, C. 1977. Studies in the intake and digestibility of two varieties (Serdang and Coloniao) of Guinea grass (Panicum maximum) by goats and sheep. Mardi Res. Bull. 5(2):110.
Dhanapala, S. B., J. Pathirana. 1972. Vet. J. 20(3):77.
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Dominguez, G. H. and A. Elias. 1981. Effect of age at cutting, the inclusion of urea and different levels of final molasses in coast cross No. 1 bermuda grass ( Cynodon dactylon L. Pers) silage quality. Cuban J. Agr. Sci. 15:77.
Dominguez, G. H. and C. Hardy. 1981. Effect of cutting age and final molasses on quality of pangola grass (Digitaria decurnbens Stent) silage. Cuban J. Agr. Sci. (Cuba) 15(3):333.
Dubois, M., K. A. Gilles, J. K. Hamilton, P. A. Rebers and F. Smith. 1956. Colorimetric method for determination of sugars and related substances. Anal. Chem. 28:350.
Dulphy, J. P. and C. Demarquilly. 1973. Influence de la machine de recolte et de la finesse de hachage sur la valeur alimentaire des ensilage. ( Influence of harvesting machine and chop length on the alimentary value of silage.) Ann. Zootechnie 22:199.
Dulphy, J. P. and B. Michalet. 1975. Influence comparee de la machine de recol te sur le quantities d' ensilage ingerees par de geni sses et des moutons. (Comparative effect of harvesting machine on silage intake by heifers and sheep.) Ann. Zootechnie 24:757.
Erwin, E. S., G. J. Marco and E. M. Emery. 1961. Volatile fatty acid analyses of blood and rumen fluid by gas chromatography. J. Dairy Sci. 44:1768.
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Grant, R. J., P. J. Vansoest, R. E. McDowell and C. B. Perez, Jr. 1974. Intake, digestibility and metabolic loss of Napier grass by cattle and buffaloes when fed wilted, chopped and whole. J. Anim. Sci. 39(2):423.
105
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APPENDIX
112
113
TAtL: 25. COMPOSITION OF THE MINERAL MIXTURE USED IN ANIMAL TRIALS (SUPER-MIX)
Item
Calcium Phosphorous Sodium chloride Vitamin/Trace element mixture Vitamin A, IU Vitamin D3 , IU Vitamin E, mg Magnesium, g Iron, g Zn, g
Manganese, g Copper, g Cobalt Iodine, g
Per kg Percent mixture
20.32 7.20
30.00 2.20
150,000 25,000
50 227
136.2 136.0 34.05 12.71
3.17 9.08
114
TABLE 26, EXA..'1PLE OF ANALYSIS OF VARIANCE,a SMALL SILO STUDY
Source Df
Model Error Corrected total
Model Growth stage Additive Growth stage x additive
Contrasts Linear growth stage Quadratic growth stage Control vs additives Fonnic acid vs cassava tuber
meal and coconut oil meal Cassava tuber meal vs coconut
oil meal
aGeneral linear model procedure.
11 60 71
2 3 6
1 1 1
1
1
115
TABLE 2 7. EXAMPLE OF ANALYSIS OF V ARIAi'JCE, a PALATABILITY TRIAL
Source Df
Model Error Corrected total
Model Trial Block Trial x block Growth stage Chopping Growth stage x chopping Trial x growth stage Trial x chopping Trial x growth stage x chopping Block x growth stage Block x chopping
aGeneral linear model procedure.
15 8
23
1 2 2 1 1 1 1 1 1 2 2
Item
TAHLE 28. FERMENTATION CHARACTERISTICS OF POST ENSILED MIXTURES (LARGE SILO)
Growth period, wk 2
Unchopped Chopped Unchopped 3
Chopped
- - % - - - - - - - - - -a b Water soluble carbohydrates '
Lactic acida,b
pH
~Dry basis. Growth period x chopping (P < .05).
3.15
.11
5.58
5.91
2.57
5.28
4.02
.07
5.7
4.07
.20
5.3
SE
.41
.08
.02
I-' I-'
°'
The vita has been removed from the scanned document
ENSILING CHARACTERISTICS, DIGESTIBILITY AND PALATABILITY
OF TROPICAL GRASSES AS AFFECTED BY GROWTH STAGE,
CHOPPING LENGTH AND ADDITIVES
Sujatha Panditharatne
(ABSTRACT}
Research was conducted in Sri Lanka to study the
effects of growth stage, chopping length and additives on
ensiling characteristics of Guinea-' A' (Panicum maximum -
Ecotype-'A') and NB-21 (Pennisetum purpureum Schumac x
Pennisetum americanum). The forages were harvested 1, 2 and
3 wk after growth, chopped and ensiled in small laboratory
silos (3 liter cardboard cylinders double lined with
polyethylene bags) alone or with additions of cassava tuber
meal, coconut oil meal and formic acid. Cutting grass at 1
wk increased (P<.05) acetic and lactic acid of silage,
compared to 3 wk. Addition of cassava tuber meal and
coconut oil meal increased (P<.05) lactic acid and decreased
(P<. 05) pH and acetic acid of silage, compared with the
control. The effects were greater for cassava tuber meal.
In a second study 3-wk growth of Guinea-' A' grass was
hand chopped to 1. 5, 7. 5 and 15 cm, and ensi led in small
laboratory silos. Lactic and acetic acid of silage
increased (P<.01), whereas dry matter loss and pH decreased
(P<.05) with fineness of chop. In a third study, 2 and 3 wk
growths of Guinea-' A' were harvested and ensi led in 210
l,i ter metal
chopped or
drums, double lined with
unchopped. Cutting grass
polyethylene bags,
at 2 wk decreased
(P<.05) pH and increased (P<.01) lactic acid, compared to 3
wk. Chopping decreased (P<.05) the pH and increased (P<.05)
lactic and acetic acid of silage.
Experiments were also conducted to study the
digestibility and palatability by sheep of Guinea-'A' silage
prepared in the third study. Apparent digestibility of dry
matter (DM), crude protein (CP), neutral detergent fiber
(NDF) and acid detergent fiber (ADF) were higher (P<.01) for
2 wk compared to 3-wk growth. Chopping the grass before
ensiling increased (P<.01) the apparent digestibility of DM,
CP, NDF, ADF and hemicellulose. No significant differences
were observed for DM intake by sheep due to the growth
stage, but chopping increased (P<.01) DM intake by 17%.
Lengthening the cutting interval of Guinea-'A' and
NB-21 resulted in linear increases (P<.01) in DM yield.