Genetic environmental trends for first lactation milk traits in the South African Ayrshire breed

Author: G.J. Hallowell, J. van der Westhuizen and J.B. van Wyk
Year: 1998
Issue: 1
Volume: 28
Page: 38 -

Estimated breeding values and genetic trends were obtained in Ayrshire cattle by using DFREML procedures for 9 050 first lactation records calving down from 1977 to 1992. Environmental trends were calculated as the difference between the phenotypic and genetic values. The Ayrshire breed showed a positive trend of 19 kg per year for milk yield, with similar trends for fat and protein yield, while the trends for fat and protein percentage were negative.

Keywords: Ayrshire, fat, genetic trends, milk protein
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