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A study was made of the records from 177 steer calves from 23 sires at the U. S. Range Livestock Experiment Station, Miles City, Montana, to estimate the relative effect of heredity on weights, gains and efficiency of gain. Two methods were used, namely: The intra-sire correlation obtained by analysis of variance, and the sire: progeny regression obtained by covariance analysis. Heritabilities obtained from intra-sire correlations for the various weights and gain were: birth weight 23 percent; weaning weight 12 percent; final feed lot weight 81 percent; gain in the feed lot 99 percent and efficiency of gain 75 percent. Heritabilities obtained from sire: progeny regression were: birth weight 42 percent; weaning weight 0 percent; final weight 69 percent; daily gain 46 percent; and efficiency of gain 54 percent. When adjustments were made for differences in feeding for the sires each year, the heritability was found to be 34 percent for birth weight, 30 percent for weaning weight, 94 percent for final weight, 97 percent for daily gain and 48 percent for efficiency of gain. The estimates of heritability obtained from these data are higher than seems reasonable and the cause or causes of these high estimates are not known. Meanwhile, these results are interpreted to indicate that the breeder and feeder of beef cattle can take encouragement from this report with respect to selection of cattle for both rate of gain and efficiency of feed utilization.
Knapp et al. (Fri,) studied this question.