CONTRIBUTION OF BREED, COW WEIGHT, AND MILK-YIELD TO THE PREWEANING, FEEDLOT, AND CARCASS TRAITS OF CALVES IN 3 BEEF BREEDING SYSTEMS

Data were obtained from 1980 to 1987 on animals belonging to one of th ree breeding systems: Hereford, small rotation, and large rotation. Di fferences among Angus-, Gelbvieh-, Pinzgauer-, and Tarentaise-sired ca lves within the small rotation system were generally not detected as s ignificant for the preweaning traits of gestation length, calving ease , birth weight, gain to weaning, or creep feed intake with the excepti on of a longer gestation length for Gelbvieh-sired calves. Similarly, differences for feedlot gain, days on feed, feedlot intake, and the ca rcass characteristics of carcass weight and marbling, and lean, fat, a nd bone percentages were generally nonsignificant. Gelbvieh- and Pinzg auer-sired calves had higher growth rate, market weight, and longissim us muscle area than Angus- or Tarentaise-sired calves with a correspon ding tendency for increased feed intake. Differences among Charolais-, Maine Anjou-, and Simmental-sired calves within the large rotation we re 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 we ights and was negatively associated with creep intake. Neither cow wei ght nor milk yield showed any consistent association with feedlot or m arket traits, although increased milk yield was shown to be associated with higher daily gains for Hereford and small rotation and with high er carcass and market weights for Hereford. In general, associations o f traits of calves with weight and milk yield of their dams were not d etected as being different among breeding systems; except the effect o f increased milk yield on gain to weaning was greater in Hereford than in large rotation cows.