Association of Preweaning and Postweaning Traits with Weaning Weight in Cattle

Abstract

Analysis of the effects of milk and butterfat production and weaning weight of the dam and birth weight, amount of creep feed, and sex of calf on weaning weight and gain to weaning of 88 offspring of 52 cows that were 2, 3 and 4 years of age indicated that these factors combined account for a highly significant portion of the total variation. The independent effects of birth weight, creep-feed consumption, sex of calf and butterfat production of the dam were significant. Whereas all measures of milk and butterfat production were significantly correlated with weaning weight and gain to weaning, only butterfat production from 0 to 60 days postpartum had a significant effect when other sources of variation were constant. Estimates of the dam's milk production appeared to be independent of the birth weight of her calf, suggesting that the total milk produced was not affected by capacity of the calf to consume it. A significant negative correlation was found between the weaning weight of the dam and her butterfat production to 60 days of age. The negative correlations between weaning weight and other measures of milk production approached significance. These results suggest a negative genetic or environmental correlation, or both, between weaning performance of the dam and the maternal environment she provides for her calf. If this correlation is genetic, selecting heifers superior in weaning weight would result in increased genetic value for growth response, but decreased milk production. Average daily gain during the later stages of the postweaning feeding period and the proportion of trimmed valuable cuts in the carcass were found to increase significantly with increased weaning weight. The external fat thickness over the 12th rib and carcass and quality grade were not associated significantly with weaning weight.