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 o f 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 pair s. The factors examined were age at weaning (early, at 103 +/- 3 d [EW] vs normal, at 203 +/- 3 d [NW]), feeding strategy (ad libitum vs postweaning p rogrammed intake), and dietary CP concentration (100 vs 120% of NRC [1984] recommended levels). Early-weaned calves had a greater (P <.001) ADG than N W calves from 103 to 203 d and reached market weight at 385 d vs 418 d for NW calves (P <.001). Likewise, steers offered feed for ad libitum consumpti on reached market weight at 394 d, compared with 409 d for programmed-intak e steers (P <.05). In Exp. 2, 64 Angus crossbred steers were either weaned at 93 +/- 3 d and fed one of four diets, weaned at 210 +/- 3 d without acce ss to creep feed, or weaned at 210 +/- 3 d with access to creep feed for 60 d prior to weaning. Early-weaned calves were heavier (P <.01) than NW calv es at 210 d if fed either 100 or 90% concentrate diets, and they had greate r (P <.001) backfat thickness at 210 d but no difference (P >.10) in longis simus muscle area compared to EW calves fed a 60% concentrate diet. At slau ghter, 80 to 100% of steers on all treatments graded low Choice or higher. Feeding high-concentrate diets to EW beef calves accelerated growth rate an d fat deposition early in the feeding period and may be a way to provide yo ung cattle for a high-quality beef market.