PSVI-21 Long-term effects of weaning and feeding strategies during early life on performance of young bulls

Abstract The study aimed to evaluate the effects of different weaning and feeding strategies on the early life Nellore cattle, on performance of the rearing phase. Nellore male calves (n = 62), weighing 159 ± 16 kg, at the age of 120 d were distributed in 12 paddocks of Urochloa brizantha cv. Marandu. The experimental design used was a randomized complete block [blocked by initial body weight (BW) of the calves], with paddock (i.e., group of the animals) as the experimental units. Four treatments were evaluated: 1) weaned at 120 d of age [T120; daily supplementation of 5.0 g/kg BW (as fed) from d 40 until d 240 of life], 2) weaned at 180 d of age [T180; daily supplementation of 5.0 g/kg BW (as fed) from d 40 until d 240 of life], 3) weaned at 240 d of age [T240C; daily creep-feeding supplementation of 5.0 g/kg BW (as fed) from d 40 until d 240 of life], and 4) weaned at 240 d of age (T240MM; free-choice access to mineral mix until 240 d of life). After 240 d of age, all animals were allocated to grazing area of Urochloa brizantha cv. Marandu (12 paddocks) and they received energetic protein supplement at 10 g/kg BWּ animal-1ּ d-1, with 220 and 180 g CP/kg DM in the dry and rainy seasons, respectively. The animals were weighed at the beginning and end of the experiment, after fasting from liquids and solids for 16 h, to evaluate the performance on the rearing period, totalizing 212 d on feeding. The data were analyzed using the MIXED procedures (SAS Institute Inc., Cary, NC, version 9.4). At the beginning of the rearing, the animals from T120 had lightest BW (230 kg) and T240C had the greatest BW (283 kg; P < 0.001). Although, the animals from T240MM and T180 had similar BW (250 vs. 246 kg, respectively), but different from T120 Table 1). At the end of the rearing, BW from T120, T180 and T240MM were similar (411, 432 and 428 kg, respectively), but the BW from T240C was the greatest (454 kg; P < 0.03). The average daily gain in the rearing phase was not affected by treatments (P > 0.59). The weaning strategy of 240 d with creep-feeding supplementation promoted greatest BW at the end of rearing phase.