INTAKE, DIGESTIBILITY AND NITROGEN UTILIZATION OF TROPICAL NATURAL GRASS HAY BY GOATS AND SHEEP 1. University of Zambia 3, Lusaka

Transcription

1 INTAKE, DIGESTIBILITY AND NITROGEN UTILIZATION OF TROPICAL NATURAL GRASS HAY BY GOATS AND SHEEP 1 E. A. Gihad 2 University of Zambia 3, Lusaka SUMMARY Digestibility and metabolism trials were conducted to study the performance of goats and sheep fed tropical natural grass (Hyparrbenia spp.) hay. Animals were fed hay ad libitum and allowed free access to water. Goats consumed more (P~.05) dry matter (gdm/kgw.7s) than sheep. The water intake (ml/gdm) by goats was lower (P<.05) than that by sheep. With the exception of crude fiber, goats and sheep exhibited similar patterns in their ability to digest the various nutrients in hay. Crude fiber digestibility was 60.25% for goats and 56.50% for sheep (P<.05). Nutritive evaluation of hay by using goats and sheep showed similar values indicating that goats were as reliable in predicting the nutritive value as were sheep. Both goats and sheep were in negative nitrogen balance. Nitrogen losses were similar for goats and sheep. Hay was not adequate to provide the animals energy and protein for maintenance. The goats' nutritional requirements were comparable to those of sheep. The advantages of higher dry matter intake, lower water consumption and higher digestive ability of crude fiber give goats a special ecological niche in the tropics. (Key Words: Intake, Digestibility, Nitrogen Utilization, Goats, Sheep, Tropical Grass Hay.) INTRODUCTION Goats differ from other ruminants in their feeding habits. The special feeding habits of goats are particularly significant in areas where quantity and quality of feeds are low, as occurs in many parts of the tropics (Devendra and Burns, 1970). Goats can subsist on what would be sub-standard levels of nutrition for other 1 Financial assistance, gratefully acknowledged, was provided by the Research and Higher Degrees Committee, University of Zambia. 2 Permanent address: Faculty of Agriculture, Cairo University, Giza, Egypt. 3School of Agricultural Sciences, P. O. Box 2379, Lusaka, Zambia. ruminants (Malechek and Leinweber, 1972). In view of its special feeding habits there is no evidence whether the goat has a digestive efficiency superior to that of other ruminants which might account for its successful adaptation to poor environments. Available literature suggests that very few digestibility trials have been conducted with goats. This is evident in a review of the digestibility of tropical grasses (Butterworth, 1967). Schneider (1947), Bell and Lawn (1957) and Devendra (1967b) showed that the digestibility of feeds by goats is similar to that by other ruminants. Despite the above reports on the goat's similarity to other ruminants in general digestive efficiency, there is considerable evidence that it is exceptionally efficient at digesting crude fiber (Hossain, 1960; Mia et al., 1960a,b; Jang and Majumdar, 1962 ; Pant et al., 1962). The objective of this study was to compare (1) the voluntary intake of dry matter and water, (2) digestibility and (3) nitrogen utilization of natural grass hay by goats and sheep in the tropics. EXPERIMENTAL PROCEDURE This study was carried out in Zambia, at an altitude of 1,200 m and of a summer-rainfall, with an average precipitation of 750 millimeters. Adult males of indigenous "Small East African" goats and "Dorper" sheep (Mason and Maule, 1960) were used in this study. The feed used in this study was hay made from natural grass growing in Zambia, which is dominated by Hyparrbenia spp. Grass was cut during the flowering stage, field dried and machine baled. Hay was of low quality and its chemical composition is presented in table 1. In this experiment twelve goats and twelve sheep were used. The design was completely randomized. Animals were weighed at the beginning and end of the experiment. The average of the two weights was used to calculate metabolic size (kg W "7s) on which voluntary dry matter intake and nitrogen 879 JOURNAL OF ANIMAL SCIENCE, Vol. 43, No. 4 (1976)

2 880 GIHAD TABLE 1. CHEMICAL COMPOSITION OF HAY Air dry Dry matter Nutrients basis basis Dry matter, % Organic matter, % Crude protein, % Crude fiber, % Ether extract, % N-free extract, % Ash, % utilization was based. The average initial weights for goats and sheep were 25.3 and 60.8 kg, respectively. Animals were confined in individual metabolism crates during the entire period of the experiment. Hay was chopped into approximately 2.5 cm lengths. Animals were fed twice daily and allowed free access to water. Voluntary dry matter intake and water con- sumption were determined for each animal during a 10-day preliminary period. Ninety percent of the daily voluntary intake was then weighed into plastic bags for each animal for a 10-day collection period and a sample saved for later analysis. Procedures for sampling of feed and collection, handling and sampling of feces and urine were similar to those described by Gihad (1976). Proximate analyses of these samples were determined by standard A.O.A.C. (1965) methods. Gross energy of feed and feces were determined by an adiabatic oxygen bomb calorimeter. Data were analysed by analysis of variance for a completely randomized design as described by Steel and Torrie (1960). RESULTS AND DISCUSSION Results of voluntary dry matter (DM) intake are shown in table 2. The data of DM intake expressed as g/kg W -75 or g/100 kg live weight showed that goats consumed more (P<.05) DM TABLE 2. INTAKE, DIGESTIBILITY AND NUTRITIVE EVALUATION OF HAY BY GOATS AND SHEEP Item Goats Mean values Sheep SE of means No. of animals Initial wt, kg Intake/day Dry matter, g (g/kgw.75) 40.5 a 35.0 b (g/100 kg live wt) 1817 a 1263 b Water, ml (ml/g DM) 1.63 a 1.97 b Digestible crude protein, g/kgw TDN, g/kgw Starch equivalent, g/kgw Apparent digestibility, % Dry matter Organic matter Crude protein Crude fiber Ether extract N-free extract Gross energy a a a a a a a b oa a a a a a.66 Nutritive value Digestible crude protein (% of DM) Digestible energy (kcal/kg DM) TDN (% of DM) Starch equivalent (% of DM) 2.86 a 2.91 a 2212 a 2211 a a a a a a'bmeans on the same line having unlike superscripts differ significantly (P<.05).

3 GOATS AND SHEEP ON TROPICAL GRASS HAY 881 than sheep. These results were similar to those reported by Majumdar (1960b), Mackenzie (1967) and Devendra (1967a) who suggested that higher dry matter intake of goats indicated their capacity to utilize food. To arrive at the amounts of water consumed by goats and sheep to satisfy their requirements, the water intake has been related to DM consumed (Koes and Pfander, 1975). The water intake of goats was lower (P<.05) than sheep, as shown in table 2. This data can be used as a realistic assessment of the minimum amounts of water that should be available to goats and sheep (A.R.C., 1965). The apparent digestion coefficients of hay nutrients when evaluated by feeding to goats and sheep are also shown in table 2. Goats and sheep exhibited similar patterns in their ability to digest the various nutrients present in hay, except goats exhibited a higher ability to digest crude fiber than sheep. The digestibility of crude fiber by goats was higher (P<.05) than that of sheep. Differences in the digestive ability between goats and sheep for all other nutrients were not significant. These results were in agreement with the findings of Jang and Majumdar (1962) and Pant et al. (1962) and conflict with the results reported by Baumgardt et al. (1964) and Jones et al (1972). The low digestibility coefficients of crude fiber by sheep may be partially attributed to high water consumptions which may have promoted faster rumen washout and hence a faster passage (Koes and Pfander, 1975). Increased water intake may also have diluted the bacterial population, hindering substrate-enzyme contact and reducing crude fiber digestion (Baker and Harris, 1947). Supporting this hypothesis, water intake by sheep was 21% higher than goats. Furthermore, the fecal fiber from sheep was higher than goats (36.29% for sheep and 34.01% for goats). This. result also aligned with the findings of Koes and Pfander (1975). However, evidence on higher crude fiber digestibility by goats than sheep in relation to water intake need further investigations. Nutritive evaluation of hay by goats and sheep showed similar values, as predicted in table 2. The differences between digestible energy (DE), digestible crude protein (DCP), total digestible nutrients (TDN) and starch equivalent (SE) values predicted by goats and sheep were not significant. The results of this study indicate that goats were as reliable as sheep in predicting the nutritive value of hay as were sheep, agreeing with Chaudhary and Majumdar (1962); Baumgardt et al. (1964) and Jones et al. (1972). Nitrogen utilization data are presented in table 3. Both goats and sheep were in negative nitrogen balance. Overall, nitrogen losses (g/kg W -7s) were similar for goats and sheep. The differences in nitrogen losses expressed as percent of nitrogen intake and digested nitrogen consumed between goats and sheep were not significant. Both goats and sheep lost weight throughout the trial because of poor energy and nitrogen intake supplied by hay. Energy intake expressed as gse/kgw "Ts by goats and sheep (table 2) was lower than the maintenance level by others (22.2 and 23.0 g for goats, Webster and Wilson (1966) and Devendra (1967a), respectively, and 24.6 for sheep, McDonald et al. (1973). The DCP intake (table 2) was also lower than the maintenance level. Reclaculating the goat's requirements TABLE 3. NITROGEN UTILIZATION OF HAY BY GOATS AND SHEEP Item Goats Sheep per per per per S E goat kg W.75 sheep kg W.75 of means Nitrogen intake, g/day Nitrogen excretion, g/day Fecal Urinary Total Nitrogen retention Gram per day Percent of intake Percent of digested a a a a ameans on the same line having unlike superscripts differ significantly (P<.05).

4 882 GIHAD from the data reported by Majumdar (1960a,b) with a biological value (BV) of 65% gives maintenance DCP of 1.97 g and 2.51 g per kg W "75 for the factorial values and the feeding trials, respectively. The A.R.C. (1965) factorial values of maintenance DCP was 1.88 g per kg W '75 for sheep. Hay as the sole source of energy and protein was not adequate and provided only half the maintenance requirements. The nitrogen balance data obtained from this experiment was compared with the protein maintenance values reported by Majumdar (1960a,b) and A.R.C. (1965) for goats and sheep, respectively. It was recognized that the nitrogen balance data are not a reliable measure of protein maintenance (Duncan, 1966). Also, on low energy diets the protein content will not be efficiently utilized (Elliott and Topps, (1963a,b). However, the minimum g DCP/kg W -75 required to cause nitrogen equilibrium, calculated as DCP intake (lost N x 100/ BV), merits some consideration, because of the lack of appropriate conclusive measures for tropical application. These values were 2.18 and 1.95 g DCP/kg W "75 for goats and sheep, respectively. Therefore, it is of interest to note that goats' requirements of protein were comparable to that of sheep and the factorial values are a reliable measure of protein maintenance for both goats and sheep. The information herein is inconclusive, but for the present purpose, may nevertheless be useful to serve as a guide in the nutrition management of goats and sheep in the tropics. This study shows that goats consumed more poor quality tropical hay with lower intake of water and digested fiber more efficiently than sheep. These advantages give goats a special ecological niche in the tropics. On the other hand, it is often suggested that goats are destructive grazers, grazing more closely on bushes as well as on the grass, thereby reducing the chances of plant regeneration from seedlings (Maher, 1945; Harvey and Rigg, 1964; Knight, 1965). However, in most cases no scientific system of goat husbandry has been applied and these criticisms of the goat are really a result of overstocking and lack of good management. LITERATURE CITED A.O.A.C Official Methods of Analyses (loth Ed.). Association of Official Agricultural Chemists. Washington, D.C. A.R.C The Nutrient Requirements of Farm Livestock, No. 2 Ruminants. Agricultural Research Council, London. Baker, F. and S. T. Harris Microbial digestion in the rumen (and caecum) with special reference to decomposition of structural cellulose. Nutr. Abstr. and Rev. 17:3. Baumgardt, B. R., W. J. Byer, H. F. Jumah and C. R. Krueger Digestion in the steer, goat and artificial rumen as measures of forage nutritive value. J. Dairy Sci. 47:160. Bell, F. R. and A. M. Lawn The pattern of rumination behaviour in housed goats. Brit. J. Anim. Behav. 5:85. Butterworth, M. H The digestibility of tropical grasses. Nutr. Abstr. and Rev. 37: 349. Chaudhary, H. P. S. and Majumder, B. N Comparative usefulness of the indicator technique in digestibility determinations of different species of animals. Annu. Biochem. Exp. Med. 22:297. Devendra, C. 1967a. Studies in the nutrition of the indigenous goat of Malaya. III. The requirements of live-weight gains. Malaysia Agr. J. 46:98. Devendra, C. 1967b. The studies in the nutrition of the indigenous goat of Malaya. V. Food conversion efficiency, economic efficiency and feeding standards for goats. Malaysia Agr. J. 46:204. Devendra, C. and M. Bums Goat Production in the Tropics. Tech. Commun. No. 19. Commonwealth Agricultural Bureaux. England. p Duncan, D. L The Balance Trial and its Limitations. In J. T. Abrams (Ed.) Recent Advances in Animal Nutrition. J. and A. Churchill Ltd. London. p Elliott, R. C. and J. H. Topps. 1963a. Studies of protein requirements of ruminants. I. Nitrogen balance trials on two breeds of African cattle given diets adequate in energy and low in protein. Brit. J. Nutr. 17:539. Elliot-t, R. C. and J. H. Topps. 1963b. Studies of protein requirements of ruminants. 2. Protein requirements of three breeds of cattle. Brit. J. Nutr. 17: 549. Gihad, E. A Value of dried poultry manure and urea as protein supplements for sheep consuming low quality tropical hay. J. Anim. Sci. 42:706. Harvey, D. and J. C. Rigg Some aspects of goats as livestock. Nutr. Abstr. and Rev. 34:641. Hossain, W Evaluation of Pipal leaves as a feed for goats. Agr. Pakistan. 11:139. Hossain, W Metabolic investigation of Bargad leaves on cattle. Agr. Pakistan. 12:212. Jang, S. and B. N. Majumdar A study of comparative digestibilities in different species of ruminants. Annu. Biochem. Exp. Med. 22:303. Jones, G. M., R. E. Larsen, A. H. Javid, E. Donefer and J. M. Gaudrean Voluntary intake and nutrient digestibility of forages by goats and sheep. J. Anim. Sci. 34:1972. Knight, J Some observations on the feeding habits of goats in the South Baringo District of Kenya. E. Africa Agr. For. J. 30:182. Koes, R. M. and W. H. Pfander Heat load and supplemental effects on performance and nutrient utilization by lambs fed orchard-grass hay. J. Anim. Sci. 40:313. Mackenzie, D Goat Husbandry. Faber and

5 GOATS AND SHEEP ON TROPICAL GRASS HAY 883 Faber Ltd. 2nd Ed. London. Maher, C The goat: friend or foe? E. Africa Agr. J. 11:115. Majumdar, B. N. 1960a. Studies on goat nutrition. I. Minimum protein requirements of goats for maintenance-endogenous urinary nitrogen and metabolic faecal nitrogen excretion studies. J. Agr. Sci. 54:329. Majumdar, B. N. 1960b. Studies on goat nutrition. II. Digestible protein requirements for maintenance from balance studies. J. Agr. Sci. 54:335. Maleehek, J. C. and C. L. Leinweber Chemical composition and in vitro digestibility of forage consumed by goats on lightly and heavily stocked ranges. J. Anim. Sci. 35:1014. Mason, I. L. and J. P. Maule The Indigenous Livestock of Eastern and Southern Africa. Commonwealth Agricultural Bureaux. England. McDonald, P., R. A. Edwards and J. F. D. Greenhalgh Animal Nutrition. Oliver and Boyd. Edinburgh. Mia, W. H., B. Sahai, B. N. Majumdar and N. D. Kehar. 1960a. Studies on tree leaves as cattle fodder. III. The nutritive value of Bargad leaves (Ficus bengalensis). Indian J. Dairy Sci. 13:1. Mia, W. H., B. N. Majumdar, B. Sahai and N. D. Kehar. 1960b. Studies on tree leaves as cattle fodder. IV. The nutritive value of Pipal leaves (Ficus religiosa). Indian J. Dairy Sci. 13:9. Pant, H. C., J. S. Rawat and A. Roy Studies on rumen physiology I. Growth of f'tstulated animals and standardisation of methods. Indian J. Dairy Sci. 15:167. Schneider, B. H Feeds of the World: Their digestibility and composition. West Virginia University, Morgantown, W. Va. Steel, R. G. D. and J. H. Torrie Principles and Procedures of Statistics. McGraw-Hill Book Co., New York, NY. Webster, C. C. and P. N. Wilson Agriculture in the Tropics. Longmans, Green and Co. Ltd. London. p