Conference Proceedings (Animal Sciences)
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- ItemDigestion and microbial protein synthesis in sheep as affected by exogenous fibrolytic enzymes(South African Society for Animal Science, 2012) Van de Vyver, W. F. J.; Useni, B. A.The aim of the study was to determine the effect of an exogenous fibrolytic enzyme (EFE) on the ruminal disappearance of dry matter (DM), neutral detergent fibre (NDF), crude protein (CP) and on the microbial protein synthesis (MPS) in sheep of a milled substrate consisting of a 50 : 50 mixture of lucerne hay (LH) and wheat straw (WS). Four cannulated Döhne-Merino sheep were randomly assigned to two groups in a 2 x 2 cross-over experiment. Additional to the in situ study, the effects of an exogenous fibrolytic enzyme (EFE) on the in vitro gas production (GP) and ANKOM digestion systems on the mixture of milled LH and WS were determined. The substrate was pre-treated with distilled water (control) or EFE (treatment) 12 hours prior to incubation to allow interaction between the substrate and enzyme. Adding EFE significantly improved the in vitro cumulative gas production (GP), but it did not affect the in vitro MPS measured as purine derivates of the GP residues. The enzyme significantly increased the in vitro DM and NDF disappearances after 36 hours. However, the in situ disappearances of DM, NDF and CP of the roughage mixture were not affected by the EFE. Further, the in situ MPS was increased significantly with the EFE treatment of the mixed substrate. It is concluded that the improved ruminal digestion of DM, NDF and CP is not only due to direct enzyme hydrolysis, but also due to the improvement of MPS.
- ItemSome insights into the phenotypic and genetic diversity of indigenous pigs in southern Africa(South African Society for Animal Science, 2012) Halimani, T. E.; Muchadeyi, F. C.; Chimonyo, M.; Dzama, K.Indigenous pigs in southern Africa are mainly owned by economically vulnerable groups in marginal areas where they are used as a source food, income and security. A study was carried out to achieve three objectives: to describe pig production systems, get a phenotypic description of the pigs and to characterize them genetically. A survey of 199 farmers in three districts in South Africa, (Vhembe, OR Tambo and Alfred Nzo) and one district in Zimbabwe (Chirumhnazu) was carried out. Additional farmers in Malawi (Dedza, Mchinji and Salima) and Zimbabwe (Mutoko) were sampled in order to meet the other two objectives. Most of the pigs (69.7%) were owned by women, with men owning 20.5% and children the remainder. Production of the pigs was constrained by several factors including disease, inadequate feeds, poor housing and lack of knowledge. The majority of the pigs were small and black with characteristics that are probably suited for thermoregulation in arid environments. The third objective was achieved through genotyping 111 pigs using 22 microsatellites. Preliminary results indicate very little differences across populations with an overall inbreeding coefficient of the subpopulation relative to the total population (FST) of 0.071. The results indicate that the indigenous pigs in southern Africa are relatively homogenous.