Sire × Environment Interactions for Growth Traits of Hereford Cattle

Twelve Hereford bulls were used to sire calves in each of three locations in North Carolina over 6 yr. Three bulls were bred artificially to a random one-third of the cows at each location each year. Locations represented the Mountain, Piedmont and Coastal Plain regions of the Southeast. As yearlings, steer progeny were fed a concentrate diet in a feedlot or grazed on pasture and then slaughtered in the fall. Performance records from 816 calves were used to evaluate sire X location interaction effects for birth weight, preweaning average daily gain and weaning weight. Performance records from 355 steers were used to investigate sire X location and sire X diet interactions for average daily gain, carcass weight and percentage fat in the rib section. For all traits, sire X location and sire X diet interactions were not significant. Estimates of genetic correlations of sire progeny performance across environments ranged from .50 to 1.25. However, when estimates of sire variances within each environment were used to adjust the genetic correlations for bias due to scale effects, all genetic correlations were greater than .90. These results suggest that sires rank similarly for breeding values across the range of locations and diets used in this study.