Revista Brasileira de Zootecnia
Print version ISSN 1516-3598
POTTER, Bernardo Augusto Albornoz; LOBATO, José Fernando Piva and TAROUCO, Jaime Urdapilleta. Post-weaning growth, visual scores at yearling age and carcass traits of heifers weaned at 100 or 180 days of age. R. Bras. Zootec. [online]. 2004, vol.33, n.6, suppl.2, pp. 2114-2122. ISSN 1516-3598. http://dx.doi.org/10.1590/S1516-35982004000800024.
This work was conducted with the aim to evaluate the influence of weaning age at 100 (EW) or 180 (CW) days old on the growth of Braford heifers until approximately 18 months old. The calves of EW were daily supplemented during 63 days, at quantity of 1% of their live weight, with a comercial ration with 18% of crude protein and 74% of total digestible nutrients. Average daily gain from birth to 205 days (G205), from this one until 365 days (G365) and from the last one until 550 days (G550) were evaluated. Live weight adjusted at 205 days (W205), at 365 days (W365) and at 550 days old (W550) were recorded. At yearling age, the visual scores of conformation (C), precocity (P) and musculature (M) were evaluated and the rib eye area (REA) and the subcutaneous fat thickness (SFT) were measured by ultrasound technique. G205 and the W205 were significantly lower for EW heifers (0.752 kg/day; 187.0 kg) than CW heifers (0.885 kg/day; 214.1 kg). However, EW heifers had G365 significantly higher (0.231 kg/day) than the CW heifers (0.112 kg/day) and, consequently, both were similar at W365 (EW= 223.9 kg; CW= 231.9 kg). The G550 did not differ among treatments, being 0.525 kg/day for the EW heifers and 0.513 kg/day for the CW heifers. Consequently, W550 was not affected by weaning age (EW= 320.6 kg; CW= 326.3 kg). The visual scores of C, P and M were not affected by the weaning age, and the means for the EW heifers were of 4.0; 4.1 and 3.6 and for the CW heifers of 4.2; 4.1 and 3.9, respectively. Weaning age also did not affect REA (EW= 41.4 cm2; CW= 43.3 cm2) and the SFT (EW= 2.5 mm; CW= 2.7 mm). The results showed that heifers weaned at 100 days of age are lighter at weaning however, with an adequate post weaning nutritional level, they get at 18 months similar live weights to that ones weaned at six months of age.
Keywords : early weaning; ultra-sound; visual scores; weight gain.