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

Abstract

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+/-3 d [EW] vs normal, at 203+/-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 < .001) ADG than NW 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 consumption reached market weight at 394 d, compared with 409 d for programmed-intake 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 access 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 calves at 210 d if fed either 100 or 90% concentrate diets, and they had greater (P < .001) backfat thickness at 210 d but no difference (P > .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.

Effects of pre-weaning concentrate feeding on calf performance, carcass and meat quality of autumn-born bull calves weaned at 90 or 150 days of age

“…Hence, when calves are weaned at 3 months of age, short-term pre-weaning concentrate feeding does not influence performance in the subsequent feedlot phase, as Tarr et al (1994) described. The better performance of TWS calves when compared with their counterparts, contradicts other results where traditionally weaned steers fed concentrates for 2 months before weaning had lower gains than early-weaned steers (Myers et al, 1999;Fluharty et al, 2000). However, in those studies traditionally weaned steers were older (7 months old) at weaning than the TW calves in the current experiment, and their milk and concentrate intake was not enough to maintain as rapid growth as the feedlot grain diet of their early-weaned counterparts.…”

“…Specifically, TWS calves had the highest weight gains, which almost doubled those of TWNS calves that were only fed on their dams' milk. The positive effect of provision of concentrate to calves late in the suckling period had already been reported in 5-month old (Faulkner et al, 1994) and 7-month old steers (Myers et al, 1999;Fluharty et al, 2000). On the other hand, EWS and EWNS calves were given ad libitum the same intensive diet and had similar performance, because they had a comparable energy intake.…”

“…In the study of Myers et al (1999), gains of traditionally weaned steers were 40% to 60% lower than those of early-weaned steers between weaning dates, which resulted in little or no compensation in gains during the finishing period. Similarly, Fluharty et al (2000) reported approximately 35% differences in weight gains between weaning dates, and no effect of age at weaning on ADG during the finishing period. Accordingly, in the current experiment, when pre-weaning concentrate feeding was not provided to the calves (TWNS and EWNS), the difference in ADG between weaning dates was 41%, and weight gains during the finishing phase did not differ with age at weaning.…”

“…Overall daily DMI and efficiency in the finishing period have been reported to be unaffected by age at weaning (Fluharty et al, 2000;Schoonmaker et al, 2004) or preweaning concentrate feeding during the nursing period (Faulkner et al, 1994;Fluharty et al, 2000;Casasú s et al, 2001b). On the other hand, the studies cited above reported Blanco, Villalba, Ripoll, Sauerwein and Casasú s a shortening of the finishing phase when starter feeds are offered to nursing calves, which also occurred in the current experiment with the TWS calves, but not with EWS calves due to their lower gains at the end of the feedlot period.…”

“…Other benefits of this feeding strategy include the reduction of weaning stress through familiarisation with concentrates as feedstuffs (Martin et al, 1981) and decreased morbidity in the feedlot (Myers et al, 1999). Carry-over effects of pre-weaning concentrate feeding on finishing performance are controversial; some studies reported slight or no effects on weight gains in the subsequent phase (Myers et al, 1999;Fluharty et al, 2000), whereas Tarr et al (1994) described deleterious effects on performance in the finishing phase. Moreover, offering starter feed to nursing calves has been reported to reduce the length of the fattening phase without affecting carcass characteristics (Corah and Bishop, 1975;Myers et al, 1999;Casasú s et al, 2001b) or even improving carcass yield grade (Faulkner et al, 1994).…”