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Comparison of dry matter intake and digestibility of sun-cured pigeon pea, alfalfa and coastal bermudagrass by growing dairy goats
Small Ruminant Research, 2 (1989)11-18 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
11
Comparison of Dry Matter Intake and Digestibility of Sun-Cured Pigeon Pea, Alfalfa and Coastal Bermudagrass by Growing Dairy Goats Y.W. PARK, G.A° REYNOLDS and T.L. STANTON International Dairy Goat Research Center, Prairie View A&M University, Texas A&M University System, Prairie View, TX 77446 (U.S.A.)
(Accepted 15 August 1988)
ABSTRACT
Park, Y.W., Reynolds, G.A. and Stanton, T.L., 1989. Comparison of dry matter intake and digestibility of sun-cured pigeon pea, alfalfa and coastal bermudagrass by growing dairy goats. Small Rumin. Res., 2: 11-18. Dry matter intake and digestibility of sun-cured pigeon pea (Cajanus cajan), alfalfa (Medicago sativa) and coastal bermudagrass (Cynodon dactylon) were studied in thirty growing Alpine dairy goats, age 7 to 9 months, assigned to three groups of ten each. The forages were offered ad libitum with supplementation of 0.454 kg yellow corn grain per animal per day. A control group of an additional 9 doelings of the same age were fed a complete ration to compare its intake with the three forage groups. In a digestion trial, six Nubian and six Alpine bucks, age 7 to 9 months were fed the three forages for three weeks. Respective average daily dry matter intake for pigeon pea, alfalfa, bermudagrass and complete ration were 61.2, 61.3, 57.8 and 79.9 gDM/day/W°'75.Respective apparent digestibility coefficients of dry matter for pigeon pea, alfalfa and bermudagrass were 51.5, 67.3 and 49.6; of crude protein 69.7, 79.4 and 43.2; and of crude fiber 30.1, 55.4 and 48.3.
INTRODUCTION T h e world goat p o p u l a t i o n is growing especially in developing c o u n t r i e s a n d t h e i r e c o n o m i c i m p o r t a n c e is b e c o m i n g m o r e a p p a r e n t . R e s e a r c h on feed values a n d digestibility of forages for goats has b e e n lagging b e h i n d o t h e r rumin a n t s (Devendra, 1980). Reviews o f t h e literature on dry m a t t e r intake ( D M I ) , b y n u t r i e n t r e q u i r e m e n t s for d i f f e r e n t classes of goats, n u t r i t i v e values a n d digestibilities of feedstuffs for goats indicate t h a t m a n y have b e e n t r a n s p o s e d f r o m cattle a n d sheep d a t a ( N R C , 1981; Kearl, 1982). B r o w s e is a m a j o r p o r t i o n o f goat diets ( H a r r i s et al., 1982). T h e browsing h a b i t o f goats can be a t t r i b u t e d to t o l e r a n c e of b i t t e r c o m p o u n d s ( G o a t c h e r a n d C h u r c h , 1970; M a l e c h e k a n d P r o v e n z a , 1981 ). A n g o r a goats on r a n g e l a n d s t r a v e l a p p r o x i m a t e l y twice t h e daily d i s t a n c e t h a t c a t t l e do in s e a r c h o f forage
0921-4488/89/$03.50
© 1989 Elsevier Science Publishers B.V.
12 (Cory, 1927 ). Goats have a greater tendency to change their diet with changing seasons, compared to cattle and sheep, and to be more selective in taking plant parts palatable to them (Fraps and Cory, 1940 ). Goats have been described as different in diet selection and gastrointestinal physiology from other domestic ruminants and similar to deer (Huston, 1978). Intake and apparent digestibility of pigeon pea compared to napier grass by lactating goats has been reported (Brown et al., 1988). Semi-arid tropical grass hay was consumed more by goats than sheep, but digestibility coefficients were similar between species except for crude fiber, which appeared to be digested better in goats (Gihad, 1976; Devendra, 1978; Gihad et al., 1980). However, crude fiber digestibility of grasses was not better in goats in other studies (Locua et al., 1982). Sheep, goats, and deer ranked in that order, but differences among them were not significant (Huston, 1976). Antoniou and Hadjipanayiotou (1985) observed higher digestibility of dry matter, organic matter and gross energy in goats when barley straw was offered alone, while sheep exceeded in digestibility of roughages when they were supplemented with concentrates. Since most of the digestion of roughage occurs in the reticulorumen, there is a close relationship between rumen size, retention time, extent of digestion, and voluntary intake (Campling, 1964). The purpose of this study was to compare dry matter intake and digestibility of sun-cured pigeon pea, alfalfa and coastal bermudagrass hay by growing goats. MATERIALAND METHODS
Preparation of forage and concentrates Pigeon peas, planted at Prairie View A&M University Cooperative Agricultural Research Farm, were harvested when 1.5 to 2 m tall as first cutting in the late vegetative stage. The hay was dried in the sun for 96 h and stored in a greenhouse. Pigeon pea stems less than 0.75 cm in diameter with intact leaves were cut into lengths of approximately 15 to 20 cm each day before feeding. Stems greater than 0.75 cm in diameter were discarded and not tested. Coastal bermudagrass was 2nd cutting with very mature stage, sun dried and baled from the same Prairie View A&M University Agricultural Research Farm. Alfalfa hay was commercially purchased from Kansas, 2nd cutting field-cured, baled at early bloom stage. The complete ration consisted of: 14.5% cottonseed meal, 13.7% No. 2 yellow corn, 10.0% oats, 10.0% alfalfa pellets, 39.6% cottonseed hulls, 10% molasses, 1.0% trace mineral salt, 1.0% CaCO3, and 0.2% of a vitamin A, D and E supplement. The complete ration was not pelleted.
13
Experimental design In a four-week feeding trial, thirty growing Alpine does of 7 to 9 months of age were randomly assigned to three forage groups (pigeon pea, alfalfa and coastal bermudagrass). Ten animals were in each treatment. An additional nine doelings of the same age, five Alpines and four Nubians, were in a complete ration for control. Animals were individually housed, fed in mangers and allowed exercise for 2 h per day. The three forage groups were fed 0.454 kg of No. 2 yellow corn per head at 9:00 a.m. every day to maintain minimum energy requirements and to simulate usual feeding conditions on goat farms. Forages and complete ration were offered twice daily at 10:00 a.m. and 4:00 p.m. for four weeks. Forages and water were offered ad libitum. Every morning, at 8:30 a.m., orts and spills were weighed and recorded. Twelve growing bucks, 7 to 9 months of age, six Alpines and six Nubians were randomly assigned to a digestion trial for three weeks with a two-week adjustment and a one-week collection period. Each buck was individually housed in a metabolism crate, and three groups of four animals each (two Alpines and two Nubians) were fed three different forages. Forages were offered ad libitum for the adjustment period and 90% of the ad libitum intake for the collection period. Forages, corn, complete ration and orts samples were collected during the entire two experimental periods, pooled, dried, ground in a 1 mm screen Wiley Mill, packed in plastic bags and sent to a laboratory for chemical analysis. Feces were collected for 7 days; 20% of the feces output for each day were sampled and stored in a freezer, pooled for each animal and about 300 g for each goat was freeze dried and chemically analyzed.
Chemical analysis Proximate analysis of feeds, orts and feces was according to AOAC procedures (1980). Tannin analyses on the three forages were done by the AOAC method (1980). Estimated total digestible nutrient (TDN) values were calculated by the equation of the Pennsylvania State University (Adams, 1975). Mineral contents were determined by atomic absorption spectroscopy (AOAC, 1980). Percent moisture, crude protein, crude fiber, and estimated T D N for sun-cured pigeon pea, alfalfa and coastal bermudagrass are shown in Table 1. Levels of five minerals (S, P, K, Mg and Ca) are also listed in Table 1.
Statistical analysis Experimental data were analyzed by analysis of variance and mean differences among levels of intake and digestibility for the three forages and complete ration as described by Steel and Torrie (1960) and Duncan (1955).
14 TABLE 1 Chemical composition (% dry matter basis) of forages,complete ration and corn grain Moisture Crude Crude TDNf Minerals protein fiber Sulphur Phos- Potas- Magne- Calcium phorus sium sium Pigeon peaa Alfalfab Bermudagrassc Complete rationd Corn graine
8.36 10.08 8.64 11.4 14.3
21.7 21.7 6.21 18.0 9.73
26.1 27.6 31.5 26.7 2.10
66.0 61.7 58.5 59.1 75.3
0.25 0.42 0.32 0.31 0.10
0.89 0.39 0.30 0.42 0.33
1.26 2.92 1.28 1.82 0.52
0.32 0.35 0.23 0.35 0.10
0.89 1.09 0.59 0.70 0.17
aVegetative first cutting, includesall leaves and 0.75 cm or less diameter stems from Prairie View A&M UniversityFarm. bCommerciallypurchased secondcutting sun-curedbaled hay. cSecondcutting baled mature stage from Prairie ViewA&M UniversityFarm. dComplete ration contained cottonseedmeal and hulls, alfalfapellets, oats, corn, molasses, minerals and vitamin supplements. eYellowNo. 2 corn harvested from Prairie View A&M UniversityFarm. fTDN values were estimated using regression equation (Adams, 1975); TDN = 93.53 - 1.03 ADF or ( - 1.29 CF) for forage and grain rations. RESULTS AND DISCUSSION Goats fed alfalfa hay had highest intake for the three forages tested (Table 2 ). However, level of feed intake for the complete control ration exceeded alfalfa and the difference was significant (P < 0.05). Highest intake for the complete ration may have been due to the smaller particle size of the complete diet, since it has been demonstrated t h a t feed intake increases as particle size of the feed is reduced (Blaxter and Graham, 1956). It is also possible the complete ration contained more palatable nutritional components t h a n the three experimental forages. It was observed t h a t goats consumed less forage when the weather was rainy or during changes of ambient temperature. Results of this study showed t h a t both alfalfa and pigeon pea were more palatable t h a n bermudagrass hay (P < 0.05 ) (Table 2). Differences between alfalfa and pigeon pea were not significant, agreeing with other reports (Dehority and Grubb, 1977) (Table 1 ). The bermudagrass contained significantly lower crude protein and higher crude fiber contents (Table 1 ) which may have contributed to the lowest feed intake among the three forages (Table 2). Bermudagrass also had lower concentrations of minerals (Table 1) wich often cause anorexia for animals {Underwood, 1977). None of the three forages contained detectable levels of t a n n i n which may alter palatability of forages, even if goats have a tolerance to bitter substances compared to other ruminants (Goatcher and Church, 1970). Average daily intake for alfalfa was again highest in the digestion trial, next
15 TABLE 2 Average daily dry matter intake ( g D M / d a y / W °'75) of pigeon pea, alfalfa, bermudagrass hay and complete ration by growing dairy goats for 4 weeks experimental period D M I n t a k e / d a y / W °'Ts
Pigeon pea" Alfalfaa Bermudagrass a Complete ration
Week 1
Week 2
Week 3
Week 4
58.5 p 61.7 q 60.3 q 85.7 r
64.3 q 61.1 q 59.9 p 76.5 r
62.2 q 58.8 p 55.4 p 79.8 r
59.8 p 61.6 q 56.3 p 77.2 r
OveralP
s.e. b
61.2 q 61.3 q 57.8 p 79.9 r
1.28 0.68 1.24 2.09
aDMI values of pigeon pea, alfalfa and bermudagrass groups include 0.454 kg yellow corn per head per day. Overall mean D M I for four weeks. Means with different superscripts within a same column are significantly different (P<:0.05). bStandard error of overall mean. TABLE 3 Comparison of apparent digestibility coefficients of dry matter (DM), crude protein (CP), crude fiber (CF) and CP absorption for goat groups fed pigeon pea, alfalfa and bermudagrass hay Hay Pigeon pea c D M intake (kg/day)" 0.693 Apparent digestibility coefficients DM 51.6 CP 69.7 CF 30.1 CP retention (g/day) CP intake 150 CP retained b 104
s.e. e Alfalfad 0.703
Bermudagrass d 0.564
0.05
67.3 79.3 55.4
49.6 43.2 48.3
5.61 10.79 7.53
153 121
35.0 15.1
38.8 32.8
"DM intake were 90% of ad libitum for each animal. bCP retained = CP i n t a k e - fecal CP. CObservations are means of 2 goats due to unavailability of pigeon pea. dObservations are means of 4 goats. ~Standard error.
highest was pigeon pea (Table 3). This observation followed the same trend in the feeding trial. Dry matter digestibility (Table 3) was positively related to levels of feed intake for the 3 forages. Crude protein digestibility of bermudagrass was significantly ( P < 0.05 ) lower than those of pigeon pea and alfalfa (Table 3 ). Gihad (1976) fed poor quality roughage of semi-arid natural grass hay of Zambia and rice straw to two breeds of goats (Small East African and Egyptian Baladi), and found that goats and sheep were in negative nitrogen balance, and the hays were not adequate to provide energy and protein necessary for animal maintenance. Similarly, the bucks in our study tended gradu-
16 ally to decrease in body weight as the digestion trial progressed. The hays, as the sole source of energy and protein, were not adequate for meeting the buck's maintenance requirements of energy and protein. Therefore, insufficient levels of protein and energy in the diet were probably not efficiently utilized as suggested by Elliott and Topps (1963). Alfalfa hay was superior to pigeon pea and bermudagrass in the digestibility of dry matter, crude protein and crude fiber by the goats (Table 3 ). Published feed composition tables (NRC, 1971; Gohl, 1981; Harris et al., 1982; Kearl, 1982) do not list in vivo digestibility data by goats of pigeon pea, alfalfa and bermudagrass hays. Crude protein (CP) digestibility of sun-cured alfalfa hay by sheep was reported as 76% and 48% for crude fiber (CF) (NRC, 1971). Digestibility coefficients for CP and CF of bermudagrass by sheep were higher than for the goats in this study. This might be due to: (a) the goats prefer legumes over grass; (b) bermudagrass in this study was too mature compared with the other forages; (c) a lower N content in bermudagrass created a negative N balance which could have affected a lower digestibility of bermudagrass. However, few studies (Hossain, 1960; Jang and Majumdar, 1962; Gihad, 1976) reported that certain breeds of goats were more efficient in digesting crude fiber than others which may deserve further investigation. Crude fiber digestibility of pigeon pea at the fresh milk stage by sheep was 38% (NRC, 1971 ), while in the present study for first cutting sun-cured hay it was 30.1%. Drying process can cause reduction of digestibility (Dehorty and Grubb, 1977 ). Digestibility of roughages can also vary with rumen size, retention time, extent of digestion and voluntary intake (Campling, 1964). Although goats had reportedly higher fiber digestibilities in a few studies, it is apparent that more research is required. Further investigations are also needed to determine differences in digestibility with different stages of maturity, species, cutting and processing of forages, using different breeds and ages of goats. ACKNOWLEDGEMENTS The authors wish to thank Dr. F. Pinkerton for his personnel and administrative support, Ms. Teresa Iglesias for her assistance in the experiment, and Ms. Loretta Glover for typing the manuscript.
REFERENCES Adams, R.S., 1975. Equations and Conversions used by the Penn State Forage Testing Service. Cooperative Extension Service, Pennsylvania State University, College Park, PA, IDF Bull. 169, pp. 55-63. Antoniou, T. and Hadjipanayiotou, M., 1985. The digestibilityby sheep and goats of five roughages offered alone or with concentrates. J. Agric. Sci. Camb., 105: 663-671.
17 AOAC, 1980. Official Methods of Analysis. Association of Official Analytical Chemists, Washington, DC, 13th ed., 738 pp. Blaxter, K.L. and Graham, N.McC., 1956. The effect of the grinding and cubing process on the utilization of the energy of dried grass. J. Agric., 47: 207-217. Brown, D., Salim, M., Chavalimu, E. and Fitzhugh, H., 1988. Intake, selection, apparent digestibility and chemical composition of Pennisetum purpureura and Cajanus Cajan foliage as utilized by lactating goats. Small Rumin. Res., 1: 59-65. Campling, R.C., 1964. Factors affecting the voluntary intake of grass. Proc. Nutr. Soc., 23: 80-88. Cory, V.L., 1927. Activity of livestock on the range. Texas Agric. Experiment Station, College Station, TX, Bull. 367. Dehority, B.A. and Grubb, J.A., 1977. Characterization of the predominant bacteria occurring in the rumen of goats (Capra hircus). Appl. and Envir. Microbiol., 33: 1030-1036. Devendra, C., 1978. The digestive efficiency of goats. World Rev. of Anita. Prod., 14: 9-11. Devendra, C., 1980. Feeding and nutrition of goats. In: D.C. Church (Editor), Digestive Physiology and Nutrition of Ruminants, Vol. 3. Practical Nutrition, 2nd ed. O&B Books, Corvallis, OR, p. 261-274. Duncan, D.B., 1955. Multiple range and multiple t-Test. Biometrics, 11: 1-42. EUiott, R.C. and Topps, J.H., 1963. Studies of protein requirements of ruminants. Two protein requirements of three breeds of cattle. Brit. J. Nutr., 17: 549-556. Fraps, G.S. and Cory, V.L., 1940. Composition and utilization of range vegetation of Sutton and Edwards Counties. Texas Agricultural Experiment Station, College Station, TX, Bull. 568. Gihad, E.A., 1976. Intake, digestibility and nitrogen utilization of tropical natural grasshay by goats and sheep. J. Anim. Sci., 43: 879-883. Gihad, E.A., E1-Bedawy, T.M. and Mehrez, A.Z., 1980. Fiber digestibility by goats and sheep. J. Dairy Sci., 63: 1701-1706. Goatcher, W.D. and Church, D.C., 1970. Taste response in ruminants. Reactions of pygmy goats, normal goats, sheep and cattle to acid and quinine. J. Anim. Sci., 31: 373-381. Gohl, B., 1981. Feed information summaries and nutritive value. Food and Agriculture Organization, United Nations, Rome. Harris, L.E., Lech, T.F.H., Kearl, L.C., Fonnesbeck, P.V. and Lloyd, H., 1982. Central and South East Asia Tables of Feed Composition. International Feedstuffs Institute, Utah Agricultural Experiment Station, Utah State Univ., Logan, UT. Hossain, W., 1960. Evaluation of Pipal leaves as a feed for goats. Agric. Pakistan, 11: 139-147. Huston, J.E., 1976. Relative digestive capacities of cattle, sheep, goats and deer for a common feed. Texas Agricultural Experiment Station, San Angelo, TX, PR-3400, p. 36. Huston, J.E., 1978. Forage utilization and nutrient requirements of the goats. J. Dairy Sci., 61: 988-993. Jang, S. and Majumdar, B.N., 1962. A study of comparative digestibilities in different species of ruminants. Ann. Biochem. Exp. Med., 22: 303-308. Kearl, L.C., 1982. Nutrient requirements of ruminants in developing countries. International Feedstuffs Institute, Utah Agricultural Experiment Station, Utah State Univ., Logan, UT. Locua, A., Antoniou, T. and Hadjipanayiotou, M., 1982. Comparative digestibility of feedstuffs by various ruminants, specially goats. 3rd. Int. Conf. Goats Prod. Dis. 10-15 January, 1982. Tucson, AZ, pp. 122-132. Malechek, J.C. and Provenza, F.D., 1981. Feeding behavior and nutrition of goats on rangelands. In: P. Morand-Fehr, A. Bourbouze and M. de Simiane (Editors), Int. Syrup. Nutr. Syst. Goats Feeding, Vol. I. Tours, pp. 411-428. NRC, 1971. In: Atlas of Nutrition Data on United States and Canadian Feeds. Subcommittee on Feed Composition Committee. Anita. Nutr. Agric. Board, National Academy of Science Press, Washington, DC.
18 NRC, 1981. Nutrient Requirements of Goats; Angora, Dairy and Meat Goats in Temperate and Tropical Countries. National Academy of Science Press, No. 15, Washington, DC. Steel, R.G.C. and Torrie, J.G., 1960. Principles and Procedures of Statistics. McGraw-Hill, New York, NY. Underwood, E.J., 1977. Trace elements in human and animal nutrition. Academic Press, New York, NY, 4th ed.
11
Comparison of Dry Matter Intake and Digestibility of Sun-Cured Pigeon Pea, Alfalfa and Coastal Bermudagrass by Growing Dairy Goats Y.W. PARK, G.A° REYNOLDS and T.L. STANTON International Dairy Goat Research Center, Prairie View A&M University, Texas A&M University System, Prairie View, TX 77446 (U.S.A.)
(Accepted 15 August 1988)
ABSTRACT
Park, Y.W., Reynolds, G.A. and Stanton, T.L., 1989. Comparison of dry matter intake and digestibility of sun-cured pigeon pea, alfalfa and coastal bermudagrass by growing dairy goats. Small Rumin. Res., 2: 11-18. Dry matter intake and digestibility of sun-cured pigeon pea (Cajanus cajan), alfalfa (Medicago sativa) and coastal bermudagrass (Cynodon dactylon) were studied in thirty growing Alpine dairy goats, age 7 to 9 months, assigned to three groups of ten each. The forages were offered ad libitum with supplementation of 0.454 kg yellow corn grain per animal per day. A control group of an additional 9 doelings of the same age were fed a complete ration to compare its intake with the three forage groups. In a digestion trial, six Nubian and six Alpine bucks, age 7 to 9 months were fed the three forages for three weeks. Respective average daily dry matter intake for pigeon pea, alfalfa, bermudagrass and complete ration were 61.2, 61.3, 57.8 and 79.9 gDM/day/W°'75.Respective apparent digestibility coefficients of dry matter for pigeon pea, alfalfa and bermudagrass were 51.5, 67.3 and 49.6; of crude protein 69.7, 79.4 and 43.2; and of crude fiber 30.1, 55.4 and 48.3.
INTRODUCTION T h e world goat p o p u l a t i o n is growing especially in developing c o u n t r i e s a n d t h e i r e c o n o m i c i m p o r t a n c e is b e c o m i n g m o r e a p p a r e n t . R e s e a r c h on feed values a n d digestibility of forages for goats has b e e n lagging b e h i n d o t h e r rumin a n t s (Devendra, 1980). Reviews o f t h e literature on dry m a t t e r intake ( D M I ) , b y n u t r i e n t r e q u i r e m e n t s for d i f f e r e n t classes of goats, n u t r i t i v e values a n d digestibilities of feedstuffs for goats indicate t h a t m a n y have b e e n t r a n s p o s e d f r o m cattle a n d sheep d a t a ( N R C , 1981; Kearl, 1982). B r o w s e is a m a j o r p o r t i o n o f goat diets ( H a r r i s et al., 1982). T h e browsing h a b i t o f goats can be a t t r i b u t e d to t o l e r a n c e of b i t t e r c o m p o u n d s ( G o a t c h e r a n d C h u r c h , 1970; M a l e c h e k a n d P r o v e n z a , 1981 ). A n g o r a goats on r a n g e l a n d s t r a v e l a p p r o x i m a t e l y twice t h e daily d i s t a n c e t h a t c a t t l e do in s e a r c h o f forage
0921-4488/89/$03.50
© 1989 Elsevier Science Publishers B.V.
12 (Cory, 1927 ). Goats have a greater tendency to change their diet with changing seasons, compared to cattle and sheep, and to be more selective in taking plant parts palatable to them (Fraps and Cory, 1940 ). Goats have been described as different in diet selection and gastrointestinal physiology from other domestic ruminants and similar to deer (Huston, 1978). Intake and apparent digestibility of pigeon pea compared to napier grass by lactating goats has been reported (Brown et al., 1988). Semi-arid tropical grass hay was consumed more by goats than sheep, but digestibility coefficients were similar between species except for crude fiber, which appeared to be digested better in goats (Gihad, 1976; Devendra, 1978; Gihad et al., 1980). However, crude fiber digestibility of grasses was not better in goats in other studies (Locua et al., 1982). Sheep, goats, and deer ranked in that order, but differences among them were not significant (Huston, 1976). Antoniou and Hadjipanayiotou (1985) observed higher digestibility of dry matter, organic matter and gross energy in goats when barley straw was offered alone, while sheep exceeded in digestibility of roughages when they were supplemented with concentrates. Since most of the digestion of roughage occurs in the reticulorumen, there is a close relationship between rumen size, retention time, extent of digestion, and voluntary intake (Campling, 1964). The purpose of this study was to compare dry matter intake and digestibility of sun-cured pigeon pea, alfalfa and coastal bermudagrass hay by growing goats. MATERIALAND METHODS
Preparation of forage and concentrates Pigeon peas, planted at Prairie View A&M University Cooperative Agricultural Research Farm, were harvested when 1.5 to 2 m tall as first cutting in the late vegetative stage. The hay was dried in the sun for 96 h and stored in a greenhouse. Pigeon pea stems less than 0.75 cm in diameter with intact leaves were cut into lengths of approximately 15 to 20 cm each day before feeding. Stems greater than 0.75 cm in diameter were discarded and not tested. Coastal bermudagrass was 2nd cutting with very mature stage, sun dried and baled from the same Prairie View A&M University Agricultural Research Farm. Alfalfa hay was commercially purchased from Kansas, 2nd cutting field-cured, baled at early bloom stage. The complete ration consisted of: 14.5% cottonseed meal, 13.7% No. 2 yellow corn, 10.0% oats, 10.0% alfalfa pellets, 39.6% cottonseed hulls, 10% molasses, 1.0% trace mineral salt, 1.0% CaCO3, and 0.2% of a vitamin A, D and E supplement. The complete ration was not pelleted.
13
Experimental design In a four-week feeding trial, thirty growing Alpine does of 7 to 9 months of age were randomly assigned to three forage groups (pigeon pea, alfalfa and coastal bermudagrass). Ten animals were in each treatment. An additional nine doelings of the same age, five Alpines and four Nubians, were in a complete ration for control. Animals were individually housed, fed in mangers and allowed exercise for 2 h per day. The three forage groups were fed 0.454 kg of No. 2 yellow corn per head at 9:00 a.m. every day to maintain minimum energy requirements and to simulate usual feeding conditions on goat farms. Forages and complete ration were offered twice daily at 10:00 a.m. and 4:00 p.m. for four weeks. Forages and water were offered ad libitum. Every morning, at 8:30 a.m., orts and spills were weighed and recorded. Twelve growing bucks, 7 to 9 months of age, six Alpines and six Nubians were randomly assigned to a digestion trial for three weeks with a two-week adjustment and a one-week collection period. Each buck was individually housed in a metabolism crate, and three groups of four animals each (two Alpines and two Nubians) were fed three different forages. Forages were offered ad libitum for the adjustment period and 90% of the ad libitum intake for the collection period. Forages, corn, complete ration and orts samples were collected during the entire two experimental periods, pooled, dried, ground in a 1 mm screen Wiley Mill, packed in plastic bags and sent to a laboratory for chemical analysis. Feces were collected for 7 days; 20% of the feces output for each day were sampled and stored in a freezer, pooled for each animal and about 300 g for each goat was freeze dried and chemically analyzed.
Chemical analysis Proximate analysis of feeds, orts and feces was according to AOAC procedures (1980). Tannin analyses on the three forages were done by the AOAC method (1980). Estimated total digestible nutrient (TDN) values were calculated by the equation of the Pennsylvania State University (Adams, 1975). Mineral contents were determined by atomic absorption spectroscopy (AOAC, 1980). Percent moisture, crude protein, crude fiber, and estimated T D N for sun-cured pigeon pea, alfalfa and coastal bermudagrass are shown in Table 1. Levels of five minerals (S, P, K, Mg and Ca) are also listed in Table 1.
Statistical analysis Experimental data were analyzed by analysis of variance and mean differences among levels of intake and digestibility for the three forages and complete ration as described by Steel and Torrie (1960) and Duncan (1955).
14 TABLE 1 Chemical composition (% dry matter basis) of forages,complete ration and corn grain Moisture Crude Crude TDNf Minerals protein fiber Sulphur Phos- Potas- Magne- Calcium phorus sium sium Pigeon peaa Alfalfab Bermudagrassc Complete rationd Corn graine
8.36 10.08 8.64 11.4 14.3
21.7 21.7 6.21 18.0 9.73
26.1 27.6 31.5 26.7 2.10
66.0 61.7 58.5 59.1 75.3
0.25 0.42 0.32 0.31 0.10
0.89 0.39 0.30 0.42 0.33
1.26 2.92 1.28 1.82 0.52
0.32 0.35 0.23 0.35 0.10
0.89 1.09 0.59 0.70 0.17
aVegetative first cutting, includesall leaves and 0.75 cm or less diameter stems from Prairie View A&M UniversityFarm. bCommerciallypurchased secondcutting sun-curedbaled hay. cSecondcutting baled mature stage from Prairie ViewA&M UniversityFarm. dComplete ration contained cottonseedmeal and hulls, alfalfapellets, oats, corn, molasses, minerals and vitamin supplements. eYellowNo. 2 corn harvested from Prairie View A&M UniversityFarm. fTDN values were estimated using regression equation (Adams, 1975); TDN = 93.53 - 1.03 ADF or ( - 1.29 CF) for forage and grain rations. RESULTS AND DISCUSSION Goats fed alfalfa hay had highest intake for the three forages tested (Table 2 ). However, level of feed intake for the complete control ration exceeded alfalfa and the difference was significant (P < 0.05). Highest intake for the complete ration may have been due to the smaller particle size of the complete diet, since it has been demonstrated t h a t feed intake increases as particle size of the feed is reduced (Blaxter and Graham, 1956). It is also possible the complete ration contained more palatable nutritional components t h a n the three experimental forages. It was observed t h a t goats consumed less forage when the weather was rainy or during changes of ambient temperature. Results of this study showed t h a t both alfalfa and pigeon pea were more palatable t h a n bermudagrass hay (P < 0.05 ) (Table 2). Differences between alfalfa and pigeon pea were not significant, agreeing with other reports (Dehority and Grubb, 1977) (Table 1 ). The bermudagrass contained significantly lower crude protein and higher crude fiber contents (Table 1 ) which may have contributed to the lowest feed intake among the three forages (Table 2). Bermudagrass also had lower concentrations of minerals (Table 1) wich often cause anorexia for animals {Underwood, 1977). None of the three forages contained detectable levels of t a n n i n which may alter palatability of forages, even if goats have a tolerance to bitter substances compared to other ruminants (Goatcher and Church, 1970). Average daily intake for alfalfa was again highest in the digestion trial, next
15 TABLE 2 Average daily dry matter intake ( g D M / d a y / W °'75) of pigeon pea, alfalfa, bermudagrass hay and complete ration by growing dairy goats for 4 weeks experimental period D M I n t a k e / d a y / W °'Ts
Pigeon pea" Alfalfaa Bermudagrass a Complete ration
Week 1
Week 2
Week 3
Week 4
58.5 p 61.7 q 60.3 q 85.7 r
64.3 q 61.1 q 59.9 p 76.5 r
62.2 q 58.8 p 55.4 p 79.8 r
59.8 p 61.6 q 56.3 p 77.2 r
OveralP
s.e. b
61.2 q 61.3 q 57.8 p 79.9 r
1.28 0.68 1.24 2.09
aDMI values of pigeon pea, alfalfa and bermudagrass groups include 0.454 kg yellow corn per head per day. Overall mean D M I for four weeks. Means with different superscripts within a same column are significantly different (P<:0.05). bStandard error of overall mean. TABLE 3 Comparison of apparent digestibility coefficients of dry matter (DM), crude protein (CP), crude fiber (CF) and CP absorption for goat groups fed pigeon pea, alfalfa and bermudagrass hay Hay Pigeon pea c D M intake (kg/day)" 0.693 Apparent digestibility coefficients DM 51.6 CP 69.7 CF 30.1 CP retention (g/day) CP intake 150 CP retained b 104
s.e. e Alfalfad 0.703
Bermudagrass d 0.564
0.05
67.3 79.3 55.4
49.6 43.2 48.3
5.61 10.79 7.53
153 121
35.0 15.1
38.8 32.8
"DM intake were 90% of ad libitum for each animal. bCP retained = CP i n t a k e - fecal CP. CObservations are means of 2 goats due to unavailability of pigeon pea. dObservations are means of 4 goats. ~Standard error.
highest was pigeon pea (Table 3). This observation followed the same trend in the feeding trial. Dry matter digestibility (Table 3) was positively related to levels of feed intake for the 3 forages. Crude protein digestibility of bermudagrass was significantly ( P < 0.05 ) lower than those of pigeon pea and alfalfa (Table 3 ). Gihad (1976) fed poor quality roughage of semi-arid natural grass hay of Zambia and rice straw to two breeds of goats (Small East African and Egyptian Baladi), and found that goats and sheep were in negative nitrogen balance, and the hays were not adequate to provide energy and protein necessary for animal maintenance. Similarly, the bucks in our study tended gradu-
16 ally to decrease in body weight as the digestion trial progressed. The hays, as the sole source of energy and protein, were not adequate for meeting the buck's maintenance requirements of energy and protein. Therefore, insufficient levels of protein and energy in the diet were probably not efficiently utilized as suggested by Elliott and Topps (1963). Alfalfa hay was superior to pigeon pea and bermudagrass in the digestibility of dry matter, crude protein and crude fiber by the goats (Table 3 ). Published feed composition tables (NRC, 1971; Gohl, 1981; Harris et al., 1982; Kearl, 1982) do not list in vivo digestibility data by goats of pigeon pea, alfalfa and bermudagrass hays. Crude protein (CP) digestibility of sun-cured alfalfa hay by sheep was reported as 76% and 48% for crude fiber (CF) (NRC, 1971). Digestibility coefficients for CP and CF of bermudagrass by sheep were higher than for the goats in this study. This might be due to: (a) the goats prefer legumes over grass; (b) bermudagrass in this study was too mature compared with the other forages; (c) a lower N content in bermudagrass created a negative N balance which could have affected a lower digestibility of bermudagrass. However, few studies (Hossain, 1960; Jang and Majumdar, 1962; Gihad, 1976) reported that certain breeds of goats were more efficient in digesting crude fiber than others which may deserve further investigation. Crude fiber digestibility of pigeon pea at the fresh milk stage by sheep was 38% (NRC, 1971 ), while in the present study for first cutting sun-cured hay it was 30.1%. Drying process can cause reduction of digestibility (Dehorty and Grubb, 1977 ). Digestibility of roughages can also vary with rumen size, retention time, extent of digestion and voluntary intake (Campling, 1964). Although goats had reportedly higher fiber digestibilities in a few studies, it is apparent that more research is required. Further investigations are also needed to determine differences in digestibility with different stages of maturity, species, cutting and processing of forages, using different breeds and ages of goats. ACKNOWLEDGEMENTS The authors wish to thank Dr. F. Pinkerton for his personnel and administrative support, Ms. Teresa Iglesias for her assistance in the experiment, and Ms. Loretta Glover for typing the manuscript.
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