EFFECT OF HIGH CONCENTRATE FEEDING ON THE CARCASS QUALITY AND FAT COLORATION OF GRASS-REARED STEERS

Abstract

Fifty yearling beef steers of primarily mixed British beef breeding, and averaging 237.8 kg (SD = 23.47) were reared on grass from April to October. They were then placed in a feedlot for finishing and serially slaughtered over a 112-day feeding period. Feedlot gains averaged 0.64 kg/day, while carcass weight increased from 380.8 to 450.2 kg and rib fat increased from 18.7 to 30.8%. After 56 days in the feedlot, all carcasses graded either A-1 or A-2. After 28 days, the amber fat color, as scored by Federal Government graders, had been reduced from 6.5 to 4.5 when rated on a scale ranging from 1 (white) to 9 (intense amber). Carotene analysis of the carcass fat demonstrated a significant reduction (P < 0.05) from 0.28 to 0.17 mg/100 g fat during the first 28-day feeding period. These findings indicate that yearling steers reared on grass and not carrying an excessive amount of subcutaneous fat can produce A-1 carcasses, with acceptable coloration, after a concentrate feedlot finishing period of 56 days.