Genetic trends in a South African Mutton Merino nucleus breeding scheme

Author: H.Q. Gray, F.W.C. Neser, G.J. Erasmus and J.B. van Wyk
Year: 1999
Issue: 1
Volume: 29
Page: 48 - 53

Genetic parameters and trends were estimated for 2296 lambs from a SA Mutton Merino nucleus breeding scheme using multiple trait mixed model procedures. Direct heritability estimates obtained for the traits were 0.32 for weaning weight, 0.03 for post-weaning average daily gain (PWADG) and 0.05 for post-weaning Kleiber ratio (KL). Maternal heritability for weaning weight was estimated as 0.15, while the estimate for permanent maternal environment as a proportion of the total variance was 0.07. The genetic correlations between weaning weight and PWADG and weaning weight and KL were –0.12 and 0.02 respectively. The estimated genetic trends for all the traits were disappointingly low, probably owing to the low heritabilities and unfavourable genetic correlations.

Keywords: genetic parameters, genetic trends, nucleus breeding scheme, SA Mutton Merino sheep
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