Fisher L J, Williams C J
J Dairy Sci. 1978 Oct;61(10):1462-7. doi: 10.3168/jds.S0022-0302(78)83750-3.
Records of gestation length and birth weight on 1522 live single births (from 1958 to 1976) of Holstein calves were from 81 sires and 552 dams. Average gestation length was 282.3 days, and average birth weight was 42.9 kg. Male calves were carried 1.7 days longer than female calves and weighed 2.9 kg more at birth. Both gestation length and birth weight increased with parity. Calves born in spring and summer were carried shorter times and weighed less than those born in fall and winter. Heritabilities of gestation length and birth weight as progeny traits were .73 and .51 and as maternal traits were .19 and .26. Genetic correlations between gestation length and birth weight were .46 as a progeny trait and .35 as a maternal trait. Genetic correlations between progeny traits and maternal traits were negative. The phenotypic correlation between gestation length and birth weight was .37, and environmental correlation was .30.
1958年至1976年期间，对81头公牛和552头母牛所产的1522头荷斯坦犊牛的单胎活产记录进行了分析，记录内容包括妊娠期长度和出生体重。平均妊娠期长度为282.3天，平均出生体重为42.9千克。雄性犊牛的妊娠期比雌性犊牛长1.7天，出生时体重比雌性犊牛重2.9千克。妊娠期长度和出生体重均随胎次增加而增加。春季和夏季出生的犊牛妊娠期较短，出生体重也低于秋季和冬季出生的犊牛。妊娠期长度和出生体重作为后代性状的遗传力分别为0.73和0.51，作为母体性状的遗传力分别为0.19和0.26。妊娠期长度和出生体重作为后代性状的遗传相关性为0.46，作为母体性状的遗传相关性为0.35。后代性状与母体性状之间的遗传相关性为负。妊娠期长度和出生体重之间的表型相关性为0.37，环境相关性为0.30。
