Identification of factors associated with variability in tenderness among beef carcasses from steers differing in breed, body type and days on feed

Angus, Charolais and Hereford feeder steers (n=208) were measured and subjectively scored for physical production traits prior to being randomly assigned to groups fed a ration of either grain or silage. Steers were terminated from feed by predetermined criteria closely associated with carcass grade. The interval between succeeding slaughter groups was determined from fat and weight curves of similar calves from past studies (Montgomery, 1978). Calves were slaughtered when the mean fat thickness (12th rib) for all steers in a pen (n=7 or 8) reached approximately 12 mm. Short loin steaks were removed from each carcass 10-14 days postmortem to facilitate palatability evaluations. Loin steaks were rated "slightly tender to moderately tender" for all breed and feeding regime groups by an 8-member, trained sensory evaluation panel. Frozen muscle fragmentation index was linearily related to days on feed for grain fed steers. Approximately 21% of the observed variation in WBS force values was attributed to environmental effects, marbling degree, and frozen muscle fragmentation index. Acceptable palatability of loin steaks (regardless of breed, body type, degree of muscling or feeding regime) is achieved when steers were fed to a 12 mm subcutaneous fat level