Masters Degrees (Animal Sciences)
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Browsing Masters Degrees (Animal Sciences) by Author "Booysen, Vernon"
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- ItemInvestigating prolificacy as a trait to sustainability in smallholder sheep farming systems in South Africa(Stellenbosch : Stellenbosch University, 2023-03) Booysen, Vernon; Molotsi, Annelin H. ; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.ENGLISH ABSTRACT: Characterisation of genes related to prolificacy is important for sustainable genetic improvement of indigenous sheep breeds in smallholder systems in South Africa. It is known that indigenous sheep are more robust and able to reproduce in adverse conditions in comparison to exotic sheep breeds. Genetic mutations occur commonly within genes and are responsible for the observed phenotypic variation between breeds within a species. The first objective of this study was to determine whether there were any genetic mutations between indigenous breeds in known fecundity genes, growth differentiation factor 9 (GDF9) and bone morphogenetic protein receptor type 1B (BMPR1B), in four South African indigenous sheep breeds. The second objective was to elucidate the phylogenetic relationship between these breeds based on the sequence information of the two genes under investigation. A total of 52 blood samples were collected from four sheep breeds (Karakul=8; Damara=8; Zulu=18; Pedi=18). Unlabeled forward and reverse primers were used to amplify GDF9 and BMPR1B genes. The results revealed point mutations between sheep breeds in the GDF9 and BMPR1B gene compared to that of the Ovis aries consensus sequence found in GenBank. From the 52 animals sampled, there were 13 individuals that had point mutations for the GDF9 gene and 7 individuals for the BMPR1B gene. Mutations of GDF9 gene, (c.142C>T) and (c.151G>C), were detected in individuals of the Karakul, Damara, and Zulu sheep. The results also show that the BMPR1B gene has a mutation at position (c.80G>C) between individuals of the Zulu and Pedi sheep. Molecular phylogenetic analysis for both genes using the Maximum Parsimony method indicates relatedness between the Zulu and Pedi sheep. The Damara and Karakul breeds also show more relatedness based on the two gene sequences. The phylogenetic analysis provides useful information for understanding the relationships between indigenous breeds and the differences in the expression of reproduction genes. Polymorphism between and within the sheep breeds could be an indication of genetic variation that is possibly associated with higher prolificacy in indigenous sheep breeds. Prolificacy will become increasingly important for the sustainability of sheep farming systems in terms of higher reproduction performance, especially for smallholder sheep farmers with indigenous breeds that contain valuable genetic resources.