Genetic trends of selection for pelt traits in Karakul sheep. II. Correlated responses

Author: J.C. Greeff, A.S. Faure, G.J. Minnaar and S.J. Schoeman
Year: 1993
Issue: 5
Volume: 23
Page: 170 - 175

Correlated responses of curl development, hair quality, hair thickness, hair stiffness, hair length, lustre and pattern to selection for an increase in pattern and hair quality and a decrease in hair length and curl development were determined with mixed model methodology in a single trait selection experiment with Karakul sheep. No unfavourable genetic associations between pelt traits were found. The genetic relationship between pattern and hair quality was small and insignificant, which implies that pattern and hair quality can be improved together. A decrease in curl development resulted in an accompanying decrease in pattern. Selection for shorter hair resulted in an increase in pattern and vice versa. In most cases the correlations between relative breeding values were in the same direction and did not differ greatly from the estimated genetic correlations. The correlation of hair quality and its components, i.e. hair stiffness and hair thickness with some of the other pelt traits, differed from the estimated parameters. Mixed model methodology made it possible to detect more subtle correlated responses that would otherwise not have been possible.




Keywords: Correlated responses, Karakul sheep, pelt traits, selection
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