CORRELATIONS FOR GENETIC EXPRESSION FOR GROWTH OF CALVES OF HEREFORD AND ANGUS DAMS USING A MULTIVARIATE ANIMAL-MODEL

The purpose of this study was to estimate the correlation between the expression of genes from sires in purebred and crossbred progeny (r(PC )) and in Hereford and Angus F1 calves (r(HA)). Performance traits wer e weights at birth, 200 d, and 365 d. Progeny from Hereford, Polled He reford, and Angus bulls mated to Hereford or Angus cows were used to e stimate r(PC). Progeny from Charolais, Shorthorn, Simmental, Limousin, Maine-Anjou, Chianina, Gelbvieh, Tarentaise, and Salers bulls mated t o Hereford or Angus cows were used to estimate r(HA). Performances in purebreds (P) and crosses (C) or in Hereford (H) and Angus (A) F1 calv es were treated as separate traits. A multivariate animal model with b irth year-cow age-sex subclasses, random correlated direct and materna l additive genetic effects, and maternal permanent environmental effec ts was used. Separate analyses were done by breed of sire. A derivativ e-free algorithm was used to obtain REML, estimates of (co)variance co mponents. Weighted averages across breeds of estimates of heritability for P, C, H, and A were, respectively, .61, .51, .47, and .40 for bir th weight, .41, .46, .37, and .34 for weaning weight, and .50, .49, .4 2, and .46 for yearling weight. Estimates of r(PC) ranged from .88 to .97, .55 to .94, and .68 to .86 for weights at birth, 200 d, and 365 d , respectively. Estimates of r(HA) ranged from .43 to .99, .56 to .95, and .50 to .98 for weights at birth, 200 d, and 365 d, respectively. Weighted averages of estimates of r(PC) and r(HA) across sire breeds w ere, respectively, .93 and .85 for birth weight, .77 and .73 for weani ng weight, and .76 and .86 for yearling weight. These results indicate that ranking of sires producing purebreds or crosses, or crossbred ca lves from different breeds of dams, is approximately the same for birt h and yearling weights, but some reranking might occur for weaning wei ght.