Genetic and Phenotypic Relationships Between Certain Body Measurements and First Lactation Milk Production in Dairy Cattle ,

Abstract

Genetic and phenotypic correlations between milk production and six body measurements taken at five ages were estimated to study tbe usefulness of body measurements in predicting future milk production. Measurements of body length, chest depth, heart girth, paunch girth, weight, and withers height were obtained at 3, 6, 12, and 18 months of age and at 3 months postpartum, from two experiment station Holstein herds and one experiment station Guernsey herd. Correlations were estimated from 157 daughter-dam pairs and from paternal sister analyses involving from 371 to 452 daughters of 71 sires.Phenotypic correlations between measurement traits and milk production fell between −.1 and 0.1, and were not significantly different from zero. Estimates of genetic correlations were mostly positive, but only the correlation between 12-month weight and milk production of 0.43±0.19 differed significantly from zero.Body measurements seem to be of little value in predicting milk production, but there appears to be no basis for the often-encountered claim of a genetic antagonism between measures of body size and milk production in dairy cattle.