Growth-promoting implants and nutrient restriction before feeding: Effect on finishing performance, carcass composition, carcass quality, and consumer acceptability of beef1

The objectives of this experiment were to determine the effect of a prefinishing implant strategy and plane of nutrition on feedlot performance, carcass characteristics, and beef quality. Calves were weaned in the fall (n = 120 and 96 for yr 1 and 2, respectively) and finished as calves (CFED) or follow ing a growing-backgrounding program with ADG of 0.45 (RSTR) or 0.91 kg/d (UNRSTR). Before finishing, half of each group received hormonal implants with 200 mg of progesterone and 20 mg of estradiol benzoate for steers or 200 mg of testosterone propionate and 20 mg of estradiol benzoate for heifers (IMPL), whereas the other half did not receive an implant until entry into the feed yard (DLY). Growing phase ADG was greater (P < 0.01) for IMPL, but subsequent finishing ADG was not affected (P = 0.98). Greater HCW (P < 0.01) was observed with UNRSTR than CFED or RSTR, but no effect (P = 0.92) of implant was noted. Marbling scores and ratings for tenderness, juiciness, and flavor were greater (P < 0.01) for CFED than UNSTR or RSTR. Whereas IMPL cattle tended (P = 0.06) to have lower marbling scores than DLY cattle. Steaks from IMPL had greater (P = 0.03) shear force values, as well as lower (P ≤ 0.05) ratings for tenderness, juiciness, and beef flavor intensity than DLY. Results indicated that CFED produced higher quality carcasses and more palatable beef than RSTR, and prefinishing IMPL negatively affected beef quality and palatability.