Effects of Metabolic Imprinting on Growth Performance of Early-weaned Beef Steers

This study evaluated the effects of calf management system following early-weaning (EW) on performance of beef steers. On d 0, Brahman x British steers (n = 40; bodyweight [BW] = 198 ± 26 lb; age = 72 ± 14 d) were stratified by age and BW, and randomly assigned to normal-weaning (NW; d 177) or 1 of 3 EW treatments: 1) EW and grazed on ryegrass pastures for 67 d then on bahiagrass pastures until shipping (d 260; Ryegrass); 2) EW and fed a high-concentrate diet in drylot until d 260 (Drylot); or 3) EW and metabolically imprinted by feeding a high-concentrate diet for 94 d then grazed on bahiagrass pastures until d 260 (MI). Within each treatment, steers were assigned to 1 of 2 pens. Concentrate was limit fed at 1 % of BW from d 177 to 260, 7 to 260 and 94 to 260 for NW, Ryegrass and MI steers, respectively. Shrunk BW was measured at normal-weaning and feedlot entry. Carcass ultrasound was measured on d 260. At normal-weaning, Drylot steers were heavier (652 lb; P < 0.01) than the other treatments, whereas NW and Ryegrass steers had similar BW (475 and 432 lb, respectively; P = 0.14), but were lighter (P ≤ 0.04) than MI steers (535 lb). Similarly, at the time of shipping (d 260), Drylot steers were heavier (793 lb; P < 0.01) than all other treatments, whereas NW and Ryegrass steers had similar BW (504 and 507 lb, respectively; P = 0.94), and were lighter (P ≤ 0.01) than MI steers (610 lb). On d 260, Drylot steers had greater (P ≤ 0.01) ribeye area (REA) and back fat thickness (6.54 in and 0.07 in., respectively) than the other treatments. In addition, MI steers had greater REA than Ryegrass steers (5.14 and 4.19 in, respectively; P = 0.02), with NW steers being intermediate (4.57 in). Thus, feeding a high-concentrate diet to EW steers for at least 94 d (Drylot and MI) increased BW at the time of NW and at shipping compared with steers weaned at a normal age or early-weaned and grazed on pasture with 1% concentrate supplement.