Weaning weight (WW) records of 2,160 registered Angus calves were used to compare different models of evaluation, to estimate genetic trend and to estimate the relationship between the US base for WW and the base in the two herds under study. Calves were the progeny of 55 bulls and were born during 1973 to 1984. The models analysed considered sires unrelated vs. sires related and sires nested within genetic groups vs. ignoring groups. Mixed model and REML procedures were used to obtain group and sire solutions and the variance components, respectively. The range on Expected Progeny Differences (EPDs) was between 17.7 and 19.1 kg. (2.8 to 3.1 cr) .
It was observed a positive genetic trend for the north american bulls and the home bred sires showed higher solutions with the increase in north american blood. Correlations among the four methods were between 0.646 to 0.969. Inclution of the relationship matrix resulted in decreased Standard Error of Prediction (SEP) by 3.7 to 22.9% depending on group. The relationship between the US base and the base in these herds was measured by the equation EPD local =-5.37 + 0.85 EPD-USA.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XII. Biotechnology, selection experiments, parameter estimation, design of breeding systems, management of genetic resources., , 464–468, 1986
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