PATERNAL HALF-SIB HERITABILITIES AND GENETIC, ENVIRONMENTAL, AND PHENOTYPIC CORRELATION ESTIMATES FROM RANDOMLY SELECTED HEREFORD CATTLE

Growth and carcass data were collected during 10 yr at the Fort Keogh Livestock and Range Research Laboratory in Miles City, MT from a Heref ord herd selected at random. The objective was to compare genetic para meter estimates from this randomly selected herd with estimates from p ublished selection studies. Only bulls were included in the data set. Bulls were slaughtered between 14 and 17 mo of age. Genetic parameters were estimated by the paternal half-sib procedure. Data were subdivid ed into three subgroups: 1) all bulls that had birth weights, 2) bulls with complete records for growth traits, and 3) bulls with complete c arcass and growth records. The heritability estimate for birth weight on 736 progeny from 86 sires was .18. The second group included 616 pr ogeny representing 85 sires and heritability estimates were weaning we ight, .17; daily gain from birth to weaning, .20; final test weight, . 42; and daily gain on test, .47. The third group included 401 progeny from 75 sires and heritability estimates were carcass weight, .38; lon gissimus muscle area, .51; marbling, .31.; slaughter weight, .42; and dressing percentage, .25. Thus, these estimates of heritability were i n quite good agreement with previously published values, with a tenden cy for these estimates to be lower for early growth weights. Phenotypi c and environmental correlations were in good agreement and genetic co rrelations were in general agreement with the data reviewed. Estimates of heritabilities from this herd selected at random were not larger t han previous estimates from selected herds.