Desempenho de novilhos em pastagens de Brachiaria decumbens submetidos a diferentes regimes alimentares

Abstract

An experiment was conducted at the Brazilian Agricutural Reserch Corporation (EMBRAPA) National Center for Research on Beef Cattle (CNPGC), Campo Grande, MS, Brazil, on Brachiaria decumbens pastures. The objectives were to evaluate systems seeking to reduce the slaughter age and to determine in which phase of animal's life would feeding supplementation be more economic. Sixty Nellore weaned calves were randomly assigned in the following treatments: A) no supplementation; B) supplementation during the first dry season after weaning; C) supplementation during the second of the animal's life; D) supplementation during both dry seasons; and E) supplementation during the first dry season and feedlot in the second one. The experimental period was from weaning to slaughter (440 kg). The supplement utilized was 75% of grounded corn ear and 25% of soybean meal mixture, supplied daily at about 0,8% of liveweight. The confined steers received, ad libitum, a diet containing 60% of corn silage and 40% of concentrate (73% corn grain, 25% soybean meal, 1% urea and 1% sodium bicarbonate). During the first dry season, the supplemented calves showed higher daily gains than those not supplemented 1030 and 320 g, respectively. In the second dry season, the confined steers presented the highest daily gains (1080 g), followed by supplemented ones (582 g), while steers being not supplemented lost weight (- 94 g). In both wet seasons, the steers not supplemented during the previous dry season presented compensatory gains; however, even the higher gain was not enough to allow them to reach the slaughter point at the same age, since these steers extended the time needed to reach slaughter weight: 35.3; 30.6; 28.7; 26.6 and 22.6 months, for treats A, B, C, D, and E, respectively. An economical analysis was performed to detect the benefits from weight gain as well as the applicable costs for each treatment, considering time of the monetary value during the production process. Supplementary feeding, either combined with confinement or not, is ecomomically feasible. The treatment with highest net present value (NPV) was D, animals supplemented on pasture during the two dry seasons, whereas A, animals never supplemented, resulted in the lowest NPV.