Sire Breed Effects in Matings with Angus Cows: II. Carcass Characteristics of Steer Progeny3

Abstract

Carcass data from 190 steers sired by Angus (A), Charolais (C) and Holstein (F) bulls bred to Angus cows, were analyzed by least-squares procedures to estimate effects of sire breed and postweaning management on carcass weight, composition and quality of steers fed a high forage diet. Data were adjusted separately to a common live weight or slaughter age. Using either method of adjustment, CA steers had larger carcass weights per day of age, rib eye areas (REA) and REA/100 kg carcass weight and lower yield grades than FA and AA steers. At the same live weight, AA steers were older and scored higher in marbling than CA and FA steers. The CA steers also had lower marbling scores, lower carcass grades, more desirable yield grades and poorer tenderness scores than FA steers. At the same slaughter age, CA steers had heavier carcasses than both FA and AA steers. The AA steers had less kidney and pelvic fat, thicker backfat and less desirable yield grades than the larger CA and FA steers. The FA steers were more tender (P<.05) than CA steers. No significant differences in marbling or carcass grade existed at a constant slaughter age. Postweaning management had no effect on carcass characteristics. Because these three breed types differed in rate of maturity, neither a common slaughter age nor a common slaughter weight was necessarily most appropriate as a slaughter end point. Comparison of regressions of carcass characteristics on age and live weight indicate that each type has its own optimum end points for yield and quality.