Variation in Postweaning Weight Gains of Steers Independent of Appetite

A total of 87 Hereford steers, including 18 paternal half-sib groups, were individually fed a standard ground ration in eight trials. Each trial lasted 32 weeks. Daily feed allotments were restricted to the expected minimum consumption of any contemporary steer. The mean weekly feed consumption was 47.2 kg when a phenotypic CV of 1.7%. The mean weekly weight gain was 5.1 kg with a phenotypic CV of 9%. Since variation in feed consumption among contemporary steers was essentially eliminated by the experimental feeding procedure, variation in weight gain provided direct evidence of differences in intrinsic efficiency of feed utilization for growth and maintenance. Variation among paternal half-sib groups for average weekly gain was significant (P<.05), suggesting that additive genetic variation existed for efficiency of feed utilization.