Heritability Estimates of Gestation Length and Birth Weight in Holstein-Friesian Cattle and their use in Selection Indexes

Abstract

I:[eritabilities of gestation length and birth weight of 958 Holstein calves were 0.60 0.12 and 0.34 ~ 0.09, respectively, after the data were adjusted for the effects of herd, sex, paYity, year, and season. The least-squares means for birth weight and gestation length were 93.5 lb and 277.4 days, respectively. The correlations between birth weight (BW) and gestation length (GL) were: phenotypic, 0.43; genotypic, 0.37; and environmental, 0.52. The index for selection for shorter gestation length is I = --GL + 0.10 BW and the index for selection for lower birth weight is I = --BW --0.14 GL.