Calving Ease and Growth Rate of Simmental-Sired Calves. II. Genetics Parameter Estimates

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Abstract
Records from 17,297 half and three-quarter Simmental calves sired by 287 purebred Simmental bulls were used to estimate the heritability of calving ease score, percent assisted births, birth weight, 205-day weight and average daily gain from birth to weaning. Data were analyzed by the least-squares mixed model procedure with management unit (herd weaning weigh data group) and sire within management unit as the random effects and percent Simmental of the calf (50 or 75%), sex of calf (bull or heifer), age of dam and certain two-factor interactions as the fixed effects. In some analyses, birth weight was used as a covariate. Heritability estimates were .32, .21, .31, .22 and .16 for calving ease score, percent assisted births, birth weight, 205-day weight and ADG, respectively. The genetic correlations indicated that calving ease and percent assisted births were positively correlated with birth weight but not related to 205-day weight and ADG. When birth weight was included in the model as a covariate, calving ease score and percent assisted birth had a negative genetic correlation with 205-day weight and ADG. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science