Selection on BLUP of breeding values in a South African Merino stud [Best Linear Unbiased Prediction; sheep]. [Congress paper]
1994
van Wyk, J.B. | Erasmus, G.J. | Olivier, J.J. (Orange Free State Univ., Bloemfontein (South Africa))
Direct and maternal variance components and resulting heritabilities were estimated by DFREML-procedures for clean fleece weight (CFW), body weight (BW) and mean fibre diameter (MFD) in the Grootfontein Merino stud. The maternal additive variance estimates were low, resulting in heritabilities of 0.013 for BW, 0.027 for CFW and 0.012 for MFD. It is concluded that the maternal component can be ignored due to its relative small effect on these traits. The second part of the study was to estimate the response to selection on BLUP of breeding values for the traits considered over a period of 26 years. The selection policy was to increase BW, decrease MFD and maintain CFW. The observed annual trends were plus 0.63 kg for BW, minus 0.16 micron for MFD and zero for CFW. It was found that selection on BLUP of breeding values leads to a marked increase in genetic progress in spite of present practical limitations post by high culling rates on visual appearance.
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