Contribution of breed, cow weight, and milk yield to the preweaning, feedlot, and carcass traits of calves in three beef breeding systems.

Data were obtained from 1980 to 1987 on animals belonging to one of three breeding systems: Hereford, small rotation, and large rotation. Differences among Angus-, Gelbvieh-, Pinzgauer-, and Tarentaise-sired calves within the small rotation system were generally not detected as significant for the preweaning traits of gestation length, calving ease, birth weight, gain to weaning, or creep feed intake with the exception of a longer gestation length for Gelbvieh-sired calves. Similarly, differences for feedlot gain, days on feed, feedlot intake, and the carcass characteristics of carcass weight and marbling, and lean, fat, and bone percentages were generally nonsignificant. Gelbvieh- and Pinzgauer-sired calves had higher growth rate, market weight, and longissimus muscle area than Angus- or Tarentaise-sired calves with a corresponding tendency for increased feed intake. Differences among Charolais-, Maine Anjou-, and Simmental-sired calves within the large rotation were not significant for any of the traits studied. Increased cow weight was positively associated with birth weight, significantly so for the small rotation. No patterns of association with cow weight were found for other preweaning traits. Increased milk yield was positively, but not always significantly, associated with gestation length and all weights and was negatively associated with creep intake. Neither cow weight nor milk yield showed any consistent association with feedlot or market traits, although increased milk yield was shown to be associated with higher daily gains for Hereford and small rotation and with higher carcass and market weights for Hereford. In general, associations of traits of calves with weight and milk yield of their dams were not detected as being different among breeding systems; except the effect of increased milk yield on gain to weaning was greater in Hereford than in large rotation cows.