Heritabilities of Certain Immature and Mature Body Measurements and Their Correlations with First-Lactation Production of Holstein Cows

Abstract

Heritabilities of body weight estimated from heart girth, height at withers, chest depth, and body length taken at three ages before calving, after first calving, and after five years of age, along with phenotypic and genetic correlations between these traits and first-lactation mature equivalent milk or milk fat yields of Holstein cows were computed. Heritabilities and genetic correlations for precalving-age measurements were obtained from paternal-sister and also from daughter-dam resemblances. The remaining estimates were based on paternal-sister data. The analyses included 529 to 2,367 observations.Estimates of heritability from all available paternal-sister data for body measurements at three, six, and 12 months of age varied from .10 to .52. Similar estimates from regression of daughters on dams ranged from −.06 to +.61. Phenotypic correlations between body measurements taken at precalving ages and milk or milk fat yields varied from −.03 to +.15. Genetic correlations between body weight or chest depth at three, six, or 12 months of age and production from all available paternal-sister data ranged from .34±.27 to .90±.34. Similar genetic correlations for the two remaining traits were usually positive but lower. In contrast with this, genetic correlations from daughter-dam analyses varied from −.45 to +.31.A 25% increase in accuracy of selection for first-lactation milk production was indicated for inclusion of precalving age body measurements in a selection index. Similar selection restricted to body measurements would have been 80% as effective as selection based on a milk record.