Browsing by Author "Olivier, Willem J."

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    The evaluation of a South African fine wool genetic resource flock
    (Stellenbosch : Stellenbosch University, 2014-04) Olivier, Willem J.; Cloete, Schalk W. P.; Van Wyk, J. B.; Snyman, M. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: This study set out to determine (co)variance components for the important production, reproduction and conformation traits of a South African fine wool resource flock that was established at the request of the South African wool industry. A secondary aim was to assess progeny of these animals under pastoral conditions in areas where the production of fine wool is uncommon. The Cradock fine wool Merino stud was established in 1988 with ewes bought from producers with the finest clips in South Africa. Data collected from 1988 to 2010 were used to estimate the (co)variances for the genetic fine wool resource flock. The quantification of the interdependencies of fibre diameter (FD) with production, reproduction and subjective traits were the main objective of this study. It is evident from the results of this study that FD is a highly heritable (0.63 ± 0.03) trait, which can lead to marked genetic progress provided that there are adequate levels of phenotypic variation available during selection. Fibre diameter was unfavourably correlated with body weight (0.30 ± 0.05), clean fleece weight (0.24 ± 0.05) and reproduction (0.59 ± 0.18), which implies that selection for reduced FD can have a detrimental effect on all these traits. Despite these unfavourable genetic correlations genetic gain in the other economical important traits was achievable in the stud (-0.129 ± 0.033). These results were supported by the results obtained during the evaluation of progeny of this stud under pastoral conditions where the production and reproduction of the fine wool animals were comparable with medium wool animals. It can therefore be concluded that selection for reduced FD can be practiced without detrimental effects on the economically important traits and subsequently the profitability of the sheep enterprise, as long as breeders have a reasonable selection objective based on economic considerations.