PSXI-7 Sustainable intensification of the beef cattle production system in Brazil: animal performance in growing phase in pasture.

摘要

The trial aimed to evaluate the effect of sustainable intensification of the production system on final body weight (BWf), average daily gain (ADG), gain by area (GA), stocking rate (SR), production and morphogenic composition of the forage. Nellore young bulls (n=44) and ½Angus x ½Nellore (n=44) were randomly assigned in two systems in growing phase (IS=intensive and SIS=semi intensive). The IS - 6 paddocks of cv Xaraés with 2 ha each, were fertilized with 40 kg/ha of P O , 40 kg/ha of K O and 150 kg/ha N, splitted in three applications of 50 kg/ha during the rainy season, with urea as a nitrogen source. The SIS - 8 paddocks of cv Marandu, with 2 ha each didn′t receive any fertilization in the last 5 years. The animals were supplemented with mineral salt from December to February. February to May the animals received protein supplementation in 0.1 %BW. The supplement was formulated with ingredients that no compete with human or monogastrics food and without antibiotics. The results were analyzed by ANOVA using PROC MIXED procedures in SAS 9.4, with a 2 × 2 factorial arrangements, and the averages were compared at 5% level of significance. The production system influenced (P<0.0001) BWf, ADG, GA and SR (459 and 428 kg, 1.09 and 0.92 kg/day, 4.50 and 1.85 AU/ha, 30.90 and 9.05 @/ha, IS and SIS, respectively). The animals of Angus crossbreed showed higher BWf, ADG, AG and SR in relation to Nellore animals (P<0.05). Forage production, percentage of green leaf, green stem and dead matter were influenced by the production system (7.43 and 4.71 t/ha, 30.50 and 19.75%, 32.17 and 18.66%, 37.34 and 61.59%, P<0.001, SI and SSI, respectively). Animal performance, productivity and forage production were directly affected by the system intensification.