Feedlot performance and carcass evaluation of heifers fed finishing diets as weanling calves or as yearlings

Twenty commercial Herefored, Angus and Hereford × Angus, weanling and yearling heifers from the same herd were compared for feedlot performance and certain carcass characteristics. Yearlings tended to gain weight more rapidly than did weanlings. Since the cattle were group-fed, no analyses of feed efficiency could be performed. Yearlings appeared, however, to require less feed per unit of gain. The cattle were slaughtered when live weight approached 443 kg. Weanlings were fatter; had more kidney, pelvic and heart fat; merited higher (less desirable) USDA yield grades; had more desirable USDA quality grades and higher dressing percentage (P<0·05) than did yearlings. Ribeye area was not different between treatments. Yearlings yielded a higher percentage of closely trimmed retail lean cuts than did weanlings (P < 0·05). Sensory panel scores were higher (more desirable) for weanlings than for yearlings for both ribeye and inside round steaks (P < 0·05), while no differences were identified for flavor, juiciness or overall palatability of steaks. Warner-Bratzler shear force data generally supported taste panel evaluations for tenderness. These data suggest that carcass composition is impacted by the way cattle are managed and refute the idea that cattle have the same body composition at a given weight regardless of age at slaughter or nutrient density of the diet during finishing.