Effects of weaning age and diet on growth and carcass characteristics in steers

Two experiments were conducted to determine the effects of diet on growth of steers weaned at approximately 100 vs 205 d of age. In Exp. 1, a 2 x 2 x 2 factorial experiment was conducted using 78 Angus crossbred cow-calf pairs. The factors examined were age at weaning (early, at 103 [+ or -] 3 d [EW] vs normal, at 203 [+ or -] 3 d [NW]), feeding strategy (ad libitum vs postweaning programmed intake), and dietary CP concentration (100 vs 120% of NRC [1984] recommended levels). Early-weaned calves had a greater (P [is less than] .001) ADG than NW calves from 103 to 203 d and reached market weight at 385 d vs 418 d for NW calves (P [is less than] .001). Likewise, steers offered feed for ad libitum consumption reached market weight at 394 d, compared with 409 d for programmed-intake steers (P [is less than] .05). In Exp. 2, 64 Angus crossbred steers were either weaned at 93 [+ or -] 3 d and fed one of four diets, weaned at 210 [+ or -] 3 d without access to creep feed, or weaned at 210 [+ or -] 3 d with access to creep feed for 60 d prior to weaning. Early-weaned calves were heavier (P [is less than] .01) than NW calves at 210 d if fed either 100 or 90% concentrate diets, and they had greater (P [is less than] .001) backfat thickness at 210 d but no difference (P [is greater than] .10) in longissimus muscle area compared to EW calves fed a 60% concentrate diet. At slaughter, 80 to 100% of steers on all treatments graded low Choice or higher. Feeding high-concentrate diets to EW beef calves accelerated growth rate and fat deposition early in the feeding period and may be a way to provide young cattle for a high-quality beef market. Key Words: Beef Cattle, Meat Quality, Weaning