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Effect of plane of nutrition on body weight and birth weight of pregnant Gwembe Valley goats in Zambia
SmallRuminant Research, 9 (1992) 201-208
201
© 1992 Elsevier Science Publishers B.V. All rights reserved. 0921-4488/92/$05.00
Effect of plane of nutrition on body weight and birth weight of pregnant Gwembe Valley goats in Zambia E.M. Aregheore, C.O.C. Chibanga and J.C.N. Lungu Department of Animal Science, School of Agricultural Sciences, Universityof Zambia, Lusaka, Zambia (Accepted 20 January 1992)
ABSTRACT Aregheore, E., Chibanga, C.O.C. and Lungu, J.C.N., 1992. Effect of plane of nutrition on body weight and birth weight of pregnant Gwembe Valley goats in Zambia. SmallRumin. Res., 9: 201-208. Pregnant Gwembe Valley goats, aged 18-24 months, with an average BW of 23.2+0.82 kg were used. In addition to hay, they were fed concentrate mixtures for 12 weeks that contained 12.2, 13.3 or 13.7 MJ GE/kg and 14.3, 13.4 and 12.2% CP. Three dietary treatments were high protein-low energy (HL), medium protein-medium energy (MM) and low protein-energy (LH). Voluntary daily intake of concentrate before kidding was 0.53 + 0.08, 0.62 + 0.10 and 0.48 + 0.08 kg/doe for HL, MM and LH, respectively;and intake was more (P< 0.05) in MM. Average daily live weight gains were 25 + 0.08, 43 + 0.53 and 24 + 0.08 g/doe forHL, MM and LH groups. Intakes of concentrates after kidding were not significantly different (P> 0.05 ); however, hay intakes differed (P< 0.05) between groups. Mean birth weights of kids were 1.24+0.41, 1.60+0.13 and 1.63+0.09 kg for HL, MM and LH groups. Birth weights of kids were not different (P> 0.05) between MM and LH, but they differed slightly from the HL group. Apparent digestibility coefficients were significantly influenced (P< 0.05) by levels of protein and energy. From these results, the estimated optimal protein and energy requirements in concentrate supplements for pregnant Gwembe Valley goats is 13.4% CP and 13.3 MJ GE/ kg, since body weight and birth weight were best at that level.
INTRODUCTION
Information on the nutrition of tropical goats is scant, except for some recent attempts to determine nutritional requirements of some tropical breeds of goats for growth, maintenance, reproduction and lactation (Akinsoyinu, 1974; Akinsoyinu et al., 1975; Mba et al., 1975; NRC, 1981; Onwuka and Akinsoyinu, 1989; Abate, 1989; Hassan, 1989; Osuagwuh and Akinsoyinu, 1990). In tropical Africa, there is a variety of breeds of goats, each adopted to Correspondence to and present address: E.M. Aregheore, School of Sciences, College of Education, P.M.B. 1251, Warri, Nigeria.
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E.M. AREGHEOREET AL.
particular environmental conditions, and having differing nutritional requirements. Norton (1984) provided information on protein requirements of cashmere-bearing goats, and estimates of protein and energy requirements of goats have been reported by Akinsoyinu et al. (1975) and Osuagwuh (1984). At present, no information is available on the protein and energy requirements of Gwembe Valley goats, a predominant breed found in the Southern province in Zambia. The population of the Gwembe Valley goats is 340 000 (Kasonde, 1990). An estimate of dietary protein, and energy levels at which efficiency of utilization is optimal, is essential for the understanding of the nutritional requirements of pregnant Gwembe Valley goats in Zambia. This study was intended to contribute to this knowledge, particularly when goats were fed diets of different protein and energy levels, with a view to determining optimal levels for pregnancy and growth. MATERIALS A N D M E T H O D S
Nine pregnant Gwembe Valley goats were divided, on the basis of weight into three groups in a completely randomized design experiment. The goats, aged 18-24 months and weighing 23.2_ 0.82 kg, were subjected to synchronized mating and were in week 9 of pregnancy at the start of the experiment. They were housed in individual pens that had been previously disinfected. Pens had concrete floors covered with woodshavings as litter. Feed and water troughs for individual feeding and watering were in each pen; attached to each pen was a metal rack for hay. The nine does were fed concentrates at three protein and energy levels, 14.3, 13.3 or 12.2% CP, and 12.2, 13.3 and 13.7 MJ GE/kg, for 12 weeks. Components of concentrates are shown in Table 1. Each doe was fed 1.5 kg concentrate plus 1.0 kg hay (Hyparrhenia spp. ) in two equal portions at 8:30 and 17:30 h. Weekly records of individual feed intake and body weight were kept. Feeds not consumed within 24 h, were weighed and sampled for subsequent analysis. During week 11, digestibility studies were carried out with the total collection method. Daily consumption of experimental concentrates and hay were recorded for each goat. Faeces were collected for 7 days, weighed, and a 25% sample was removed for DM determination. Faeces were dried in a forced air oven at 70°C for 24 h. Daily samples of faeces, concentrates and hay were bulked, sampled and milled with a Christy and Norris hammer mill (Process Engineers, Chelmsford, UK) to pass through a 1.7-mm sieve. Samples were stored in air-tight bottles until chemical analysis. During kidding, assistance was available to the doe if required. Immediately after kidding, both the doe and kids were weighed.
EFFECTOF NUTRITIONON BODYWEIGHTAND BIRTHWEIGHTOF GOATS
203
TABLE 1
Composition of experimental diets ~ fed to goats Treatments2
Ingredients (%) Maize Malt Screenings Maize bran Sunflower meal Mineral-Vitamin Mix 3 Salt Chemical composition (%) 4 DM CP Ash EE NDF ADF ADL Hemicellulose Cellulose GE (MJ/kg)
HL
MM
LH
19.90 29.90 30.70 17.50 1.50 0.50
19.90 32.70 29.90 15.50 1.50 0.50
25.90 35.90 23.90 12.50 1.50 0.50
91.70 14.30 4.70 5.70 30.90 22.50 4.00 8.40 23.20 12.20
92.70 13.40 5.20 5.50 32.50 23.40 5.20 9.10 23.40 13.30
92.70 12.20 6.60 5.20 37.90 25.50 6.70 12.40 25.40 13.70
lAir dry basis: hay contained 92.9% DM, 3.9% CP, 5.4% ash, 78.7% NDF, 41.1% ADF, 11.50% ADL, 37.6% hemicellulose, 35.0% cellulose, and 9.1 MJ GE/kg. 2First letter in each treatment designates protein level, and the second letter designates energy level: H, high, M, medium, L, low. 3Supplied the following: 0.5 milli IU vitamin A; 125 milli IU vitamin Da, 1.33 g cobalt, 250 g calcium, 22.57 g copper, 41.73 g iron, 44.18 g manganese, 38.22 g zinc and 11.34 g magnesium. aDM basis.
Analytical methods Proximate chemical analyses of concentrates, hay and faecal samples were done according to AOAC (1980). GE values were determined by a bomb calorimeter (Adiabatic bomb, Parr Instrument Co., Moline, IL) using thermochemical benzoic acid as standard. Samples of concentrates, hay and faeces were analyzed for NDF and ADF according to Goering and Van Soest (1970). Hemicellulose and cellulose were estimated by differences between NDF and ADF, and ADF and ADL plus ash, respectively. Apparent digestibility coefficients were calculated by difference. All data on voluntary feed intake, body weight and birth weight of does, kid's birth weight and apparent digestibility coefficients of nutrients were subjected to analysis of variance (Steel and Torrie, 1980). Duncan's New Multiple Range Test was used to test differences between means.
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RESULTS
Data on voluntary feed intake and body weight of does before kidding are shown in Table 2. Voluntary concentrate intake fluctuated from the start to week 9 (week 18 of pregnancy) of the trial. Mean daily concentrate intake values of 0.53 + 0.08, 0.62 _ 0.10 and 0.48 + 0.08 kg/day/doe were obtained for HL, MM and LH treatments, respectively. Voluntary concentrate intake was higher (P< 0.05 ) in the does that received the MM diet, while the least intakes were of the LH diet. Hay intake was not significantly different (P> 0.05) among the three dietary treatments. Average daily feed intake (concentrate+hay) did not differ among does on the three treatments (P> 0.05 ). Final average live weights of does were 25.47 _+0.90, 27.07 _+0.10 and 24.83 _ 0.78 kg for HL, MM and LH treatments, respectively. Daily live weight gains were 25 _+0.08, 43 + 0.52 and 24 ___0.08 g for HL, MM and LH, respectively. There were significant differences (P< 0.05 ) in the final average live weight and average daily live weight gain. Feed efficiency values were not significantly different (P>0.05) between does on HL and LH treatments; however, the best feed efficiency was obtained in does that received the MM dietary treatment. Data on doe performance after kidding are given in Table 3. Voluntary intake of concentrates during this period was slightly above intake before kidding (P< 0.05 ). However, concentrate intake did not differ among does in the three dietary treatments. Hay intakes were lower (P< 0.05) than before kidding. Average BW after kidding was 21.42___0.18, 22.57_+0.01 and 20.23 _+0.35 kg for HL, MM and LH dietary treatments, respectively, and were significantly different (P< 0.01 ). Total number of kids born and their mean weight expressed according to sex and treatment group are listed in Table 4. A total of three kids were lost TABLE2 Effects of dietary protein level and energy density on feed intake and BW of does before kidding Parameters
Initial average BW (kg) Final average BW (kg) 12 weeks Average daily gain (g/day) Hay intake (kg/day) Concentrate intake (kg/day) Average daily feed intake (kg/day) (concentrate + hay ) Feed efficiency (feed/gain)
Treatments HL
MM
LH
23.33 + 0.98 25.47 + 0.90 25 + 0.08 0.68 + 0.02 0.53 + 0.081'2 1.21 +0.10
23.50 + 0.62 27.07 + 0.10 43 + 0.52 0.65 + 0.10 0.62 + 0.101 1.27+0.20
22.83 + 0.86 24.83 + 0.78 24 + 0.08 0.68 + 0.06 0.48 + 0.082 1.16+0.14
4.84_+ 1.252
2.25 _+0.041
4.83_+ 1.75 2
~'2Values on the same row with different superscripts differ significantly ( P < 0.05 ).
205
EFFECTOF NUTRITIONON BODYWEIGHTAND BIRTHWEIGHTOF GOATS TABLE 3 Effects of dietary protein level and energy density on feed intake and BW of does after kidding Parameters
Treatments
Average BW before kidding (kg) Final average BW after kidding (kg)* Average BW change (kg) Hay intake (kg/day) Concentrate intake (kg/day) Average daily feed intake (kg/day) (concentrate + hay )
HL
MM
LH
25.47 _+0.90 21.42-+0.181'2 4.05_+ 0.92 0.46-+2.982 0.65-+ 1.08
27.07 -+0.10 22.57-+0.011 4.50-+ 0.09 0.58"+ 1 . 1 5 1 0.70-+0.18
24.83 -+0.78 20.23"+0.352 4.60-+ 0.43 0.49+_0.062 0.65"+0.48
1.11 -+4.06
1.28 -+ 1.33
1.14-+0.54
"2Values on the same row with different superscripts differ significantly (P< 0.05, °P< 0.01 ).
TABLE 4 Effects of dietary protein and energy density on BW of does and birth weight of kids Parameters
Treatments
Final BW of does after kidding (kg) No. of kids Mean birth weight of female kids (kg) Mean birth weight of male kids (kg)
HL
MM
LH
21.42"+0.18 5 0.96 "+0.002,3 1.24+0.412
22.57"+0.01 6 1.12_+ 0.032 1.60+_0.131
20.23_+0.35 5 1.50 "+0.00 L 1.63+0.09 ~
L2,3Values on the same row with different superscript differ significantly (P< 0.05 ).
TABLE 5 Apparent digestibility coefficients of nutrients Nutrients (%)
DM CP NDF ADF Hemicellulose Cellulose GE
Treatments HL
MM
LH
73.63 73.61 64.23 62.92 63.23 58.52 67.02
77.01 70.82 70.2' 68.11 73.8' 67.8' 75.8'
74.52 66.33 68.52 69.0' 67.82 68.8' 77.3'
1,2,Walues in the same row with different superscript differ significantly (P< 0.05 ).
206
E.M. AREGHEORE El" AL.
at birth or soon after, one from treatment HL and two from treatment LH. Mean birth weights of male kids were significantly higher (P< 0.05 ); for female kids; birth weight was highest (P< 0.05 ) in the LH treatment. Mean BW for both sexes were 1.24___0.41, 1.60___1.13 and 1.63_+0.09 kg for HL, MM and LH, respectively. There was no statistically significant difference (P> 0.05 ) between MM and LH kids, but they were different (P< 0.05 ) from HL kids in birth weight. Apparent digestibility coefficients (Table 5 ) for CP and GE were significantly higher (P< 0.05) for does on HL and LH. However, for fibres they were significantly lower (P< 0.05 ) in does on HL treatment.
DISCUSSION
The relative fluctuation in voluntary intake of concentrates may be due to the enlargement of the uterus during pregnancy which eventually competes with the digestive organs for space within the abdomen. Forbes (1987) reported that in situations where the physical capacity of the stomach is an important limit to intake, this competition will lead to depression in intake in pregnant ruminants. Another possible reason for fluctuation or reduction in concentrate intake could be reduction in rumen contents, which occurs during mid and late pregnancy. The lower intake obtained in LH treatment could be associated with the energy level of the concentrate mixture. It has been observed that ruminants on high energy diets consume less to meet their energy requirements for growth and reproduction (Aregheore et al., 1988; Hassan, 1989). Variations observed in BW before and after kidding are probably a result of the weight of foetus and the physiological state of the goats. BW gains differed from Hassan (1989) who reported increased BW for does as digestible energy increased. In this trial, final BW was less in the LH dietary treatment which had the highest level of digestible energy; however, BW data for LH and HL dietary treatments indicated that protein and energy requirements of the does, were not met, while MM dietary treatment was sufficient in protein and energy for maintenance and growth of does. Results of the LH and HL dietary treatments suggested that high energy and high protein fed separately have an effect on growth of pregnant Gwembe Valley goats. Dietary energy and protein should be in equilibrium at a particular level, as obtained in the MM group to meet requirements of the pregnant doe for growth. In the HL group, irrespective of protein level, birth weights of kids were lower. This indicated the importance of energy over protein for reproductive performance, supporting earlier reports of Sachdeva et al. ( 1973 ) with Bar-
EFFECT OF NUTRITION ON BODY WEIGHT AND BIRTH WEIGHT OF GOATS
207
bari and Jamunapari kids from does on different planes of nutrition. Thomson and Thomson ( 1948 ) found that ewes on a low plane of nutrition produced smaller and weaker lambs, most of which died at birth or soon after, compared with vigorous lambs, with fewer deaths, from ewes on a high plane of nutrition. Does on the MM and LH dietary treatments produced more healthy kids than the HL does, indicating that goats responded more to dietary energy concentration rather than protein. On the basis of mean birth weight of kids, the MM and LH groups were higher, indicating that concentrate diets with 13.3 MJ GE/kg BW and 13.4% CP could meet the requirements of pregnant Gwembe Valley goats for body weight gain and production of healthy kids on average birth weight. Although birth weights of kids obtained in this trial are lower than the values of Hassan (1989) for SomaliArabian kids, the birth weight of kids increased as the digestible energy fed to the does increased. This indicated that does responded to higher digestible energy treatments. Apparent digestibility coefficients reflected nutrient components of the concentrates fed, their level and efficiency of utilization. Increased protein intake is often associated with high DM intake, resulting in a faster rate of passage of digesta through the gastro-intestinal tract. Depression in fibre digestibility with increased dietary protein has been reported (Adeneye and Oyenuga, 1976). Depression in fibre fractions in the HL concentrate seems to implicate the role of high protein intake. The results on crude protein and energy digestibility showed that does responded to the utilization of the two critical nutrients. In conclusion, the estimated protein and energy requirements of 13.4% CP plus 13.3 MJ GE/kg BW in this trial are lower than the recommendations of Akinsoyinu et al. ( 1975 ), Osuagwuh and Akinsoyinu (1990) for pregnant West African dwarf goats, and Hassan (1989) for Somali-Arabian goats. However, the breed, size, and ecological zones (Lambourne, 1984) may be implicated in the requirements. This suggests that breed and mature weight should be considered when nutrient requirements of pregnant goats are estimated. This study recommends that for a maximum performance of pregnant Gwembe Valley goats, in terms of BW, healthy birth weight, survival rate and healthy kids, a concentrate supplement that contains 13.4% CP and 13.3 MJ GE/kg BW best meets the animal's requirements and a MM dietary treatment is recommended.
ACKNOWLEDGEMENT
The authors are grateful for the financial support of IAEA Vote No. D3ZAM-5039 of the University of Zambia, Great East Road Campus, Lusaka, Zambia.
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REFERENCES Abate, A., 1989. Metabolizable energy requirements for maintenance of Kenyan goats. Small Rumin. Res., 2: 299-309. Adeneye, J.A. and Oyenuga, V.A., 1976. Energy and protein requirements of West African Dwarf Sheep. I. Effect of feeding four levels of dietary energy to sheep. E. Aft. Agric. For. J., 42: 89-97. Akinsoyinu, A.O., 1974. Studies on protein and energy utilization by the West African dwarf goats. PhD Thesis, University of Ibadan, Nigeria, pp. 1-206. Akinsoyinu, A.O., Mba, A.U. and Olubajo, F.O., 1975. Studies on energy and protein utilization for pregnancy and lactation by the West African dwarf goats in Nigeria. E. Aft. Agile. For. J., 41: 167-176. AOAC, 1980. Official Methods for Analysis. 13th Edn. Association of Official Agricultural Chemists, Washington DC, pp. 1-1094. Aregheore, E.M., Job, T.A. and Aluyi, H.S.A., 1988. The maize replacement value of cassava flour in rations for growing ewe lambs. Anita. Feed Sci. Tech., 20: 233-240. Forbes, J.M., 1987. Voluntary food intake and reproduction. Proceedings of the Nutritional Society, 46:193-201. Goering, H.K. and Van Soest, P.J., 1970. Forage fibre analyses (apparatus, reagents, procedures and some applications). Agric. Handbook 379, ARS, USDA Washington DC, pp. 1-20. Hassan, H.M., 1989. Effect on Somali-Arabian goat doe body weight, birth weight and hay intake of rations of varying digestible energy fed in pregnancy. In: R.T, Wilson and A. Malaku (Editors), African Small Ruminant Research and Development, ILCA, Addis Ababa, Ethiopia, pp. 147-154. Lambourne, L.J., 1984. Research in Goat Productivity in Tropical Africa. In: Goat Production and Research in the Tropics. Proceedings of a Workshop held at the University of Queensland, Brisbane, Australia, 6-8 February, pp. 53-65. Mba, A.U., Egbuiwe, C.P. and Oyenuga, V.A., 1975. Nitrogen balance studies with red Sokoto (Maradi) goats for the minimum protein requirements. E. Afr. Agric. For. J., 40: 285-291. Norton, B.W., 1984. Nutrition of the goat: A Review. In: Goat Production and Research in the Tropics. Proceedings of a Workshop held at the University of Queensland, Brisbane, Australia, 6-8 February, pp. 75-81. NRC, 1981. Nutrient Requirements of Goats. National Research Council, National Academy of Sciences, Washington, DC, 91 pp. Onwuka, C.F.I. and Akinsoyinu, A.O., 1989. Protein and energy requirements for maintenance and gain by West African dwarf goats fed cassava (Manihot utilissima) leaves with peels as supplement. Small Rumin. Res., 2:291-298. Osuagwuh, A.I.A., 1984. Studies on the protein, energy and mineral utilization by pregnant West African dwarf (Fouta djallon) goat in humid tropical zone of Ibadan. PhD Thesis. University of Ibadan, Nigeria. Osuagwuh, A.I.A. and Akinsoyinu, A.O., 1990. Efficiency of nitrogen utilization by pregnant West African dwarf goats fed various levels of crude protein in the diet. Small Rumin. Res., 3: 363-371. Sachdeva, K.K., Sengar, O.P.S., Singh, S.N. and Lindahl, I.L., 1973. Studies on goats I. Effect of plane of nutrition on the reproductive performance of does. J. Agric. Sci. (Camb), 80: 375-379. Steel, R.G.D. and Torrie, J.H., 1980. Principles and Procedures of Statistics. 2nd Edn., McGraw Hill, New York, NY, 389 pp. Thomson, A.M. and Thomson, W., 1948. Lambing in relation to the diet of the pregnant ewe. Br. J. Nutr., 2: 290-305.
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© 1992 Elsevier Science Publishers B.V. All rights reserved. 0921-4488/92/$05.00
Effect of plane of nutrition on body weight and birth weight of pregnant Gwembe Valley goats in Zambia E.M. Aregheore, C.O.C. Chibanga and J.C.N. Lungu Department of Animal Science, School of Agricultural Sciences, Universityof Zambia, Lusaka, Zambia (Accepted 20 January 1992)
ABSTRACT Aregheore, E., Chibanga, C.O.C. and Lungu, J.C.N., 1992. Effect of plane of nutrition on body weight and birth weight of pregnant Gwembe Valley goats in Zambia. SmallRumin. Res., 9: 201-208. Pregnant Gwembe Valley goats, aged 18-24 months, with an average BW of 23.2+0.82 kg were used. In addition to hay, they were fed concentrate mixtures for 12 weeks that contained 12.2, 13.3 or 13.7 MJ GE/kg and 14.3, 13.4 and 12.2% CP. Three dietary treatments were high protein-low energy (HL), medium protein-medium energy (MM) and low protein-energy (LH). Voluntary daily intake of concentrate before kidding was 0.53 + 0.08, 0.62 + 0.10 and 0.48 + 0.08 kg/doe for HL, MM and LH, respectively;and intake was more (P< 0.05) in MM. Average daily live weight gains were 25 + 0.08, 43 + 0.53 and 24 + 0.08 g/doe forHL, MM and LH groups. Intakes of concentrates after kidding were not significantly different (P> 0.05 ); however, hay intakes differed (P< 0.05) between groups. Mean birth weights of kids were 1.24+0.41, 1.60+0.13 and 1.63+0.09 kg for HL, MM and LH groups. Birth weights of kids were not different (P> 0.05) between MM and LH, but they differed slightly from the HL group. Apparent digestibility coefficients were significantly influenced (P< 0.05) by levels of protein and energy. From these results, the estimated optimal protein and energy requirements in concentrate supplements for pregnant Gwembe Valley goats is 13.4% CP and 13.3 MJ GE/ kg, since body weight and birth weight were best at that level.
INTRODUCTION
Information on the nutrition of tropical goats is scant, except for some recent attempts to determine nutritional requirements of some tropical breeds of goats for growth, maintenance, reproduction and lactation (Akinsoyinu, 1974; Akinsoyinu et al., 1975; Mba et al., 1975; NRC, 1981; Onwuka and Akinsoyinu, 1989; Abate, 1989; Hassan, 1989; Osuagwuh and Akinsoyinu, 1990). In tropical Africa, there is a variety of breeds of goats, each adopted to Correspondence to and present address: E.M. Aregheore, School of Sciences, College of Education, P.M.B. 1251, Warri, Nigeria.
202
E.M. AREGHEOREET AL.
particular environmental conditions, and having differing nutritional requirements. Norton (1984) provided information on protein requirements of cashmere-bearing goats, and estimates of protein and energy requirements of goats have been reported by Akinsoyinu et al. (1975) and Osuagwuh (1984). At present, no information is available on the protein and energy requirements of Gwembe Valley goats, a predominant breed found in the Southern province in Zambia. The population of the Gwembe Valley goats is 340 000 (Kasonde, 1990). An estimate of dietary protein, and energy levels at which efficiency of utilization is optimal, is essential for the understanding of the nutritional requirements of pregnant Gwembe Valley goats in Zambia. This study was intended to contribute to this knowledge, particularly when goats were fed diets of different protein and energy levels, with a view to determining optimal levels for pregnancy and growth. MATERIALS A N D M E T H O D S
Nine pregnant Gwembe Valley goats were divided, on the basis of weight into three groups in a completely randomized design experiment. The goats, aged 18-24 months and weighing 23.2_ 0.82 kg, were subjected to synchronized mating and were in week 9 of pregnancy at the start of the experiment. They were housed in individual pens that had been previously disinfected. Pens had concrete floors covered with woodshavings as litter. Feed and water troughs for individual feeding and watering were in each pen; attached to each pen was a metal rack for hay. The nine does were fed concentrates at three protein and energy levels, 14.3, 13.3 or 12.2% CP, and 12.2, 13.3 and 13.7 MJ GE/kg, for 12 weeks. Components of concentrates are shown in Table 1. Each doe was fed 1.5 kg concentrate plus 1.0 kg hay (Hyparrhenia spp. ) in two equal portions at 8:30 and 17:30 h. Weekly records of individual feed intake and body weight were kept. Feeds not consumed within 24 h, were weighed and sampled for subsequent analysis. During week 11, digestibility studies were carried out with the total collection method. Daily consumption of experimental concentrates and hay were recorded for each goat. Faeces were collected for 7 days, weighed, and a 25% sample was removed for DM determination. Faeces were dried in a forced air oven at 70°C for 24 h. Daily samples of faeces, concentrates and hay were bulked, sampled and milled with a Christy and Norris hammer mill (Process Engineers, Chelmsford, UK) to pass through a 1.7-mm sieve. Samples were stored in air-tight bottles until chemical analysis. During kidding, assistance was available to the doe if required. Immediately after kidding, both the doe and kids were weighed.
EFFECTOF NUTRITIONON BODYWEIGHTAND BIRTHWEIGHTOF GOATS
203
TABLE 1
Composition of experimental diets ~ fed to goats Treatments2
Ingredients (%) Maize Malt Screenings Maize bran Sunflower meal Mineral-Vitamin Mix 3 Salt Chemical composition (%) 4 DM CP Ash EE NDF ADF ADL Hemicellulose Cellulose GE (MJ/kg)
HL
MM
LH
19.90 29.90 30.70 17.50 1.50 0.50
19.90 32.70 29.90 15.50 1.50 0.50
25.90 35.90 23.90 12.50 1.50 0.50
91.70 14.30 4.70 5.70 30.90 22.50 4.00 8.40 23.20 12.20
92.70 13.40 5.20 5.50 32.50 23.40 5.20 9.10 23.40 13.30
92.70 12.20 6.60 5.20 37.90 25.50 6.70 12.40 25.40 13.70
lAir dry basis: hay contained 92.9% DM, 3.9% CP, 5.4% ash, 78.7% NDF, 41.1% ADF, 11.50% ADL, 37.6% hemicellulose, 35.0% cellulose, and 9.1 MJ GE/kg. 2First letter in each treatment designates protein level, and the second letter designates energy level: H, high, M, medium, L, low. 3Supplied the following: 0.5 milli IU vitamin A; 125 milli IU vitamin Da, 1.33 g cobalt, 250 g calcium, 22.57 g copper, 41.73 g iron, 44.18 g manganese, 38.22 g zinc and 11.34 g magnesium. aDM basis.
Analytical methods Proximate chemical analyses of concentrates, hay and faecal samples were done according to AOAC (1980). GE values were determined by a bomb calorimeter (Adiabatic bomb, Parr Instrument Co., Moline, IL) using thermochemical benzoic acid as standard. Samples of concentrates, hay and faeces were analyzed for NDF and ADF according to Goering and Van Soest (1970). Hemicellulose and cellulose were estimated by differences between NDF and ADF, and ADF and ADL plus ash, respectively. Apparent digestibility coefficients were calculated by difference. All data on voluntary feed intake, body weight and birth weight of does, kid's birth weight and apparent digestibility coefficients of nutrients were subjected to analysis of variance (Steel and Torrie, 1980). Duncan's New Multiple Range Test was used to test differences between means.
204
E.M. AREGHEORE ET AL.
RESULTS
Data on voluntary feed intake and body weight of does before kidding are shown in Table 2. Voluntary concentrate intake fluctuated from the start to week 9 (week 18 of pregnancy) of the trial. Mean daily concentrate intake values of 0.53 + 0.08, 0.62 _ 0.10 and 0.48 + 0.08 kg/day/doe were obtained for HL, MM and LH treatments, respectively. Voluntary concentrate intake was higher (P< 0.05 ) in the does that received the MM diet, while the least intakes were of the LH diet. Hay intake was not significantly different (P> 0.05) among the three dietary treatments. Average daily feed intake (concentrate+hay) did not differ among does on the three treatments (P> 0.05 ). Final average live weights of does were 25.47 _+0.90, 27.07 _+0.10 and 24.83 _ 0.78 kg for HL, MM and LH treatments, respectively. Daily live weight gains were 25 _+0.08, 43 + 0.52 and 24 ___0.08 g for HL, MM and LH, respectively. There were significant differences (P< 0.05 ) in the final average live weight and average daily live weight gain. Feed efficiency values were not significantly different (P>0.05) between does on HL and LH treatments; however, the best feed efficiency was obtained in does that received the MM dietary treatment. Data on doe performance after kidding are given in Table 3. Voluntary intake of concentrates during this period was slightly above intake before kidding (P< 0.05 ). However, concentrate intake did not differ among does in the three dietary treatments. Hay intakes were lower (P< 0.05) than before kidding. Average BW after kidding was 21.42___0.18, 22.57_+0.01 and 20.23 _+0.35 kg for HL, MM and LH dietary treatments, respectively, and were significantly different (P< 0.01 ). Total number of kids born and their mean weight expressed according to sex and treatment group are listed in Table 4. A total of three kids were lost TABLE2 Effects of dietary protein level and energy density on feed intake and BW of does before kidding Parameters
Initial average BW (kg) Final average BW (kg) 12 weeks Average daily gain (g/day) Hay intake (kg/day) Concentrate intake (kg/day) Average daily feed intake (kg/day) (concentrate + hay ) Feed efficiency (feed/gain)
Treatments HL
MM
LH
23.33 + 0.98 25.47 + 0.90 25 + 0.08 0.68 + 0.02 0.53 + 0.081'2 1.21 +0.10
23.50 + 0.62 27.07 + 0.10 43 + 0.52 0.65 + 0.10 0.62 + 0.101 1.27+0.20
22.83 + 0.86 24.83 + 0.78 24 + 0.08 0.68 + 0.06 0.48 + 0.082 1.16+0.14
4.84_+ 1.252
2.25 _+0.041
4.83_+ 1.75 2
~'2Values on the same row with different superscripts differ significantly ( P < 0.05 ).
205
EFFECTOF NUTRITIONON BODYWEIGHTAND BIRTHWEIGHTOF GOATS TABLE 3 Effects of dietary protein level and energy density on feed intake and BW of does after kidding Parameters
Treatments
Average BW before kidding (kg) Final average BW after kidding (kg)* Average BW change (kg) Hay intake (kg/day) Concentrate intake (kg/day) Average daily feed intake (kg/day) (concentrate + hay )
HL
MM
LH
25.47 _+0.90 21.42-+0.181'2 4.05_+ 0.92 0.46-+2.982 0.65-+ 1.08
27.07 -+0.10 22.57-+0.011 4.50-+ 0.09 0.58"+ 1 . 1 5 1 0.70-+0.18
24.83 -+0.78 20.23"+0.352 4.60-+ 0.43 0.49+_0.062 0.65"+0.48
1.11 -+4.06
1.28 -+ 1.33
1.14-+0.54
"2Values on the same row with different superscripts differ significantly (P< 0.05, °P< 0.01 ).
TABLE 4 Effects of dietary protein and energy density on BW of does and birth weight of kids Parameters
Treatments
Final BW of does after kidding (kg) No. of kids Mean birth weight of female kids (kg) Mean birth weight of male kids (kg)
HL
MM
LH
21.42"+0.18 5 0.96 "+0.002,3 1.24+0.412
22.57"+0.01 6 1.12_+ 0.032 1.60+_0.131
20.23_+0.35 5 1.50 "+0.00 L 1.63+0.09 ~
L2,3Values on the same row with different superscript differ significantly (P< 0.05 ).
TABLE 5 Apparent digestibility coefficients of nutrients Nutrients (%)
DM CP NDF ADF Hemicellulose Cellulose GE
Treatments HL
MM
LH
73.63 73.61 64.23 62.92 63.23 58.52 67.02
77.01 70.82 70.2' 68.11 73.8' 67.8' 75.8'
74.52 66.33 68.52 69.0' 67.82 68.8' 77.3'
1,2,Walues in the same row with different superscript differ significantly (P< 0.05 ).
206
E.M. AREGHEORE El" AL.
at birth or soon after, one from treatment HL and two from treatment LH. Mean birth weights of male kids were significantly higher (P< 0.05 ); for female kids; birth weight was highest (P< 0.05 ) in the LH treatment. Mean BW for both sexes were 1.24___0.41, 1.60___1.13 and 1.63_+0.09 kg for HL, MM and LH, respectively. There was no statistically significant difference (P> 0.05 ) between MM and LH kids, but they were different (P< 0.05 ) from HL kids in birth weight. Apparent digestibility coefficients (Table 5 ) for CP and GE were significantly higher (P< 0.05) for does on HL and LH. However, for fibres they were significantly lower (P< 0.05 ) in does on HL treatment.
DISCUSSION
The relative fluctuation in voluntary intake of concentrates may be due to the enlargement of the uterus during pregnancy which eventually competes with the digestive organs for space within the abdomen. Forbes (1987) reported that in situations where the physical capacity of the stomach is an important limit to intake, this competition will lead to depression in intake in pregnant ruminants. Another possible reason for fluctuation or reduction in concentrate intake could be reduction in rumen contents, which occurs during mid and late pregnancy. The lower intake obtained in LH treatment could be associated with the energy level of the concentrate mixture. It has been observed that ruminants on high energy diets consume less to meet their energy requirements for growth and reproduction (Aregheore et al., 1988; Hassan, 1989). Variations observed in BW before and after kidding are probably a result of the weight of foetus and the physiological state of the goats. BW gains differed from Hassan (1989) who reported increased BW for does as digestible energy increased. In this trial, final BW was less in the LH dietary treatment which had the highest level of digestible energy; however, BW data for LH and HL dietary treatments indicated that protein and energy requirements of the does, were not met, while MM dietary treatment was sufficient in protein and energy for maintenance and growth of does. Results of the LH and HL dietary treatments suggested that high energy and high protein fed separately have an effect on growth of pregnant Gwembe Valley goats. Dietary energy and protein should be in equilibrium at a particular level, as obtained in the MM group to meet requirements of the pregnant doe for growth. In the HL group, irrespective of protein level, birth weights of kids were lower. This indicated the importance of energy over protein for reproductive performance, supporting earlier reports of Sachdeva et al. ( 1973 ) with Bar-
EFFECT OF NUTRITION ON BODY WEIGHT AND BIRTH WEIGHT OF GOATS
207
bari and Jamunapari kids from does on different planes of nutrition. Thomson and Thomson ( 1948 ) found that ewes on a low plane of nutrition produced smaller and weaker lambs, most of which died at birth or soon after, compared with vigorous lambs, with fewer deaths, from ewes on a high plane of nutrition. Does on the MM and LH dietary treatments produced more healthy kids than the HL does, indicating that goats responded more to dietary energy concentration rather than protein. On the basis of mean birth weight of kids, the MM and LH groups were higher, indicating that concentrate diets with 13.3 MJ GE/kg BW and 13.4% CP could meet the requirements of pregnant Gwembe Valley goats for body weight gain and production of healthy kids on average birth weight. Although birth weights of kids obtained in this trial are lower than the values of Hassan (1989) for SomaliArabian kids, the birth weight of kids increased as the digestible energy fed to the does increased. This indicated that does responded to higher digestible energy treatments. Apparent digestibility coefficients reflected nutrient components of the concentrates fed, their level and efficiency of utilization. Increased protein intake is often associated with high DM intake, resulting in a faster rate of passage of digesta through the gastro-intestinal tract. Depression in fibre digestibility with increased dietary protein has been reported (Adeneye and Oyenuga, 1976). Depression in fibre fractions in the HL concentrate seems to implicate the role of high protein intake. The results on crude protein and energy digestibility showed that does responded to the utilization of the two critical nutrients. In conclusion, the estimated protein and energy requirements of 13.4% CP plus 13.3 MJ GE/kg BW in this trial are lower than the recommendations of Akinsoyinu et al. ( 1975 ), Osuagwuh and Akinsoyinu (1990) for pregnant West African dwarf goats, and Hassan (1989) for Somali-Arabian goats. However, the breed, size, and ecological zones (Lambourne, 1984) may be implicated in the requirements. This suggests that breed and mature weight should be considered when nutrient requirements of pregnant goats are estimated. This study recommends that for a maximum performance of pregnant Gwembe Valley goats, in terms of BW, healthy birth weight, survival rate and healthy kids, a concentrate supplement that contains 13.4% CP and 13.3 MJ GE/kg BW best meets the animal's requirements and a MM dietary treatment is recommended.
ACKNOWLEDGEMENT
The authors are grateful for the financial support of IAEA Vote No. D3ZAM-5039 of the University of Zambia, Great East Road Campus, Lusaka, Zambia.
208
E.M.AREGHEOREETAL.
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