Effects of Sex and Sire on Performance and Carcass Traits of Hereford and Hereford-Red Poll Calves

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Abstract
Records of 34 Hereford and 33 Hereford-Red Poll steer and heifer calves born in the spring of 1960 and 1961 were used in this study. These calves were the progeny of two Hereford bulls, one selected for high and the other for low rate of gain and feed efficiency. The effects of year, sex, sire, breed of dam, sex × sire, sex × breed and sire × breed were considered in the least-squares analysis of the data. Steers had significantly (P<.05) heavier birth, weaning and final weights, faster pre- and postweaning gains, larger rib-eye areas, higher conformation scores and a lower percent fat and a higher percent of lean in the 9-10-11th rib than heifers. Calves sired by the high-gaining sire had significantly (P< .05) faster pre- and postweaning growth rates, heavier weaning and final weights, larger rib-eye areas (absolute and per 100 kg. of body weight), less fat thickness, more desirable flavor and a lower percent of fat and higher percent of lean in the 9-10-11th rib than those by the low-gaining sire. Crossbred calves were 2.6 kg. heavier at birth, 47 kg. heavier at weaning and had larger rib-eye areas and higher dressing percents than purebreds (P< .05). The purebred calves graded significantly (P<.05) higher at weaning and slaughter and had larger rib-eye areas per 100 kg. of carcass. Significant (P<.05) sire × sex interactions were observed for feed efficiency and slaughter grade. Sex × breed-of-dam interactions were significant for feed efficiency, slaughter grade, rib-eye area per 100 kg. of carcass, fat thickness, Warner-Bratzler shear, flavor and juiciness. Copyright © 1966. American Society of Animal Science . Copyright 1966 by American Society of Animal Science