BODY WEIGHTS AND DIMENSIONS OF PURELINE AND CROSSLINE HEIFERS OF THE CANADIAN DAIRY CATTLE BREEDING PROJECT

Abstract

Data on body weights and dimensions from birth to 82 wk of age on 1216 heifers of the National Cooperative Dairy Cattle Breeding Project were analyzed using best linear unbiased prediction (BLUP) procedures. The effects of station, year of birth, dam's parity, line of sire, line of dam, interaction between line of sire and line of dam and sires within sire line were estimated. Age at first calving was included in the model as a covariate for body weights and dimensions taken after 50 wk of age. All effects except sire were assumed to be fixed. The effect of station was significant (P < 0.01) for all traits studied. The effects of year of birth and dam's parity were significant (P < 0.05) for more than half of the traits studied. Line of sire, line of dam and their interaction effects were significant (P < 0.05) for most of the body weights and dimensions. The effect of line of dam was much greater than line of sire for all traits. The non-additive genetic effect from crossing lines H and A resulted in a 1.9–3.8% increase in body weights and up to 1.6% increase in body dimensions taken from birth to 82 wk of age. Key words: Body weights, dimensions, pureline, crossline, dairy cattle