Genetic and environmental trends of early growth traits in the Elsenburg Dormer sheep stud

Author: J.B. van Wyk, G.J. Erasmus and K.V. Konstantinov
Year: 1993
Issue: 3
Volume: 23
Page: 85 - 87

Data from the Elsenburg Dormer sheep stud were used to estimate genetic and environmental change in early growth traits from 1943 to 1990. Best linear unbiased predictions (BLUP) of breeding values were obtained by Restricted Maximum Likelihood (REML) procedures fitting a direct additive and maternal additive genetic model. Environmental change, calculated as the difference between phenotypic and genetic values, was found to be negative for all traits studied. Genetic trends were smaller but significantly positive. The higher maternal trends reveal that the biggest genetic improvement was in the additive genetic ability of ewes to produce faster growing or heavier lambs. The relative low but linear genetic trends suggest that selection pressure on these traits was low during the 48 years, probably owing to higher selection emphasis on traits other than the growth traits studied.


Keywords: Dormer sheep, early growth traits, genetic and environmental trends
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