Efeito da idade de desmame no desenvolvimento e nas características de carcaça de novilhos de corte

Abstract

RESUMO -Avaliou-se o efeito da idade de desmame no desempenho e nas características de carcaça de bezerros filhos de vacas cruzas zebuínas x taurinas, primíparas aos 3 anos de idade. As vacas foram mantidas durante dois invernos/primaveras, do desmame à primeira estação de monta, em pastejo rotativo em dois grupos (ponta e rapador), em pastagens de azevém anual Effect of weaning age on growth and carcass characteristics of beef steersABSTRACT -The objective of this trial was to evaluate the effect of weaning age on growth and carcass characteristics of calves from primiparous Bos indicus x Bos taurus crossbred cows. Heifers were divided in two groups according to the order of access to pasture and rotationally grazed pastures of ryegrass (Lolium multiflorum Lam) and arrowleaf clover (Trifolium vesiculosum cv. Yuchi) from weaning until their first mating season (two winter/spring seasons); animals were then transferred to native pasture in the following summer-autumn season. Calves were randomly assigned, according to breed and heifers grazing group order, to one of two weaning ages: early weaning (EW) -07 calves weaned at 70 days of age with an average body weight of 83.2 kg or conventional weaning (CW) -10 calves weaned at 180 days of age and with an average body weight of 152.0 kg in a completely randomized design. Steers were slaughtered with two years of age. Heifers grazing group did not affect calves performance. Calves in the CW treatment were heavier (202.1 kg) at one year old than those on EW (183.0 kg), but no significant difference was observed when animals were slaughtered at two years of age (CW=408.5 kg vs. EW=411.2 kg). Carcass traits such as fat thickness, conformation, "Hilton Quote" classification, and hot yield did not differ comparing EW with CW steers. Therefore, early weaning did not affect performance and carcass characteristics of steers slaughtered at two years of age.

Productivity and efficiency of cow herds submitted to two weaning ages

“…The productive performance of breeding herds may be improved by the use of improved pastures (Costa et al, 1981;Lobato et al, 1998ab;Lobato et al, 2000), lower stocking rates, and consequently higher forage availability of natural pastures (Simeone & Lobato, 1996;Fagundes et al, 2003; as well as by the use of early weaning (Simeone & Lobato, 1996;Restle et al, 2001;Almeida et al, 2002;Fagundes et al, 2003;Lobato et al, 2007).…”

“…Lower weaning weight of early weaned calves at the time of conventional weaning were reported by Restle et al, 1999, Almeida & Lobato, 2004Lobato et al, 2007. However, the evaluation of the production system or the use of different techniques within a system have to regard other benefits promoted by these techniques.…”

“…As calf development is not influenced by the use of early weaning Lobato et al, 2007;Vaz & Lobato 2010a), the higher weight gain results in higher pregnancy rates, reduced number of thin cows and risks during the winter, and higher accumulation of body reserves, which are reflected in higher milk production during the following lactation, and consequent higher calf weight gain. In cows with their last calves, this higher weight gain allows marketing fatter cows at a lower production cost (Pascoal & Vaz, 1997).…”

“…In the present study, calf managed was also changed, with the earlyweaned group presenting lower development as compared to calves submitted to conventional weaning Lobato et al, 2007).…”

“…However, calf development during the time period between the two weaning ages is compromised, but it can be later compensated by an adequate feeding supply Almeida & Lobato, 2004;Lobato et al, 2007).…”