Some Options for Improving Desert Sheep Productivity under Range Conditions in North Kordofan, Sudan.

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El Hag Faisal Mohamed Ahmed
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Sheep production situation was surveyed under sedentary systems in North Kordofan, Sudan, through a pre-tested structured questionnaire, using purposive random sampling technique. A data set on the nomadic sheep flock of EI-Obeid Research Station was also analyzed to study seasonal trends on Desert sheep productivity and to estimate some genetic parameters, using least squares mixed models procedures. Strategic supplementary feeding practices were then imposed on Desert (Hamari subtype) ewes at breeding (flushing) and at late pregnancy (steaming-up) and on ewe Iambs post weaning. The objective was to improve desert sheep productivity under range conditions. The results of the survey showed that over 97% of farmers in the area depended on open rangelands as the main feed resource for their flocks. More than 90% of sedentary farmers controlled breeding (mating) time in their sheep flocks as a strategy to match lambing with the rainy season. However, low reproductive performance and high mortality rates characterize sheep production operations under traditional sedentary systems. Major constraints to production, as reported by farmers in the area, are poor rangelands and feed resources, diseases and water scarcity. Breeding season had a highly significant effect (P<0.01) on nomadic flocks reproductive performance, ewe mortality, lamb growth and survival. Heritability estimates for Iamb weight at birth and at weaning and for weight gain from birth to 150, days were 0.27±0.113, 0.14±0.098 and 0.17±0.103, respectively. This suggested that significant improvements could be achieved through selection for high lamb weight at birth and at weaning. Genetic, environmental and phenotypic correlations were highly variable. Genetic correlations ranged from -0.86 (between lamb weight at birth and at 120 days) to 0.89 (between lamb weights at 90 and 120 days). Environmental correlations among weight traits were from 0.01 (between lamb weights at birth and 30 days) to 0.73 (between lamb weights at 120 and 150 days). Phenotypic correlations lowest estimate was 0.04 (between lamb weight at birth and at 60 days) and highest estimate was 0.86 (between lamb weights at 120 and 150 days) Prepartum supplementary feeding had a highly significant (P<0.01) effect on ewe reproductive performance. Lambing rates for control, flushed, steamed- up and flushed +steamed-up ewes were 44.0, 68.4, 87.6 and 99.0%, respectively. Respective litter weights at birth in these groups were 3.96, 4.07, 4.96 and 5.76±0.27 kg (P<0.05). Steamed-up ewes recorded lower (P<0.05) abortion and mortality rates compared to ewes that were not supplemented prepartum. Twining rate had increased from 10.0% in unsupplemented ewes to over 27.0% in flushed+ steamed-up ones. Monitoring seasonal milk progesterone profile in lambing ewes revealed significant (P<0.01) variations in concentrations. Progesterone concentrations were higher (> 2.0 ng/ml) in rainy and winter lambers compared to those lambing during summer. This indicated that ewe nutritional status during pregnancy had a marked effect on postpartum resumption of cyclicity. It also suggested that early weaning and supplementary feeding practices could be tried as an option to improve productivity through shortening of postpartum interval. Supplementary feeding of early-weaned ewe Iambs (4 months of age), during the summer months, had improved their growth rate and enhanced sexual maturity. Ewe lambs conceived at ten months of age when they reached 84.9% of their mature body weight. Higher (P<0.01) conception (92.0%) and lambing (88.0%) rates (P<0.01) and reduced mortality rates were observed in supplemented ewe Iambs in comparison with the controls. It was concluded that prepartum and post weaning supplementary feeding proved to be effective options for improving Desert sheep productivity under-range conditions in North Kordofan, Sudan. Other options could be through selection for high weight at birth and at weaning, and through alleviating dry season nutrition and water constraints. However, more data should be collected to estimate genetic parameters for reproductive performance. In addition, breeding ram characteristics should be evaluated.
Sheep Productivity Range Conditions North Kordofan Sudan
El Hag Faisal Mohamed Ahmed,Amir Mohamed Salih- Mohamed Khair Abdalla Ahmed/Some Options for Improving Desert Sheep Productivity under Range Conditions in North Kordofan, Sudan ._ Khartoum :unsisterly of Khartoum,1999._28cm._ ph.D