Desempenho de bovinos de corte e indicadores qualitativos de capim-marandu em sistemas integrados

Abstract

Brazil is responsible for much of the world's meat and grain production, directly contributing to global food security. And, intensification of production systems can expand this potential, mainly through integrated systems. In this perspective, two studies were carried out, the first to evaluate forage production and nutritive value and the second to evaluate the animal performance of beef cattle in integrated systems. The experiment was carried out in a randomized block design with four replicates. The treatments were four production systems in two seasons. The systems were: livestock (L); livestock-forestry (LF) integration with palisadegrass and triple lines of eucalyptus trees; crop-livestock integration (CL); and croplivestock-forestry (CLF) integration with simple eucalyptus lines. The seasons were defined by dry and rainy period. Forage production and animal performance was evaluated from July 2016 to July 2017, the nutritive value by grazing simulation was evaluated from September 2015 to March 2017. For animal performance, Nellore steers with initial weight of 345 ± 8.0 kg were managed under continuous stocking and variable rate. Forage mass (FM) and accumulation (FA) were quantified every 28 days. Greater FA were observed in the systems (CL and CLF). The individual body weight (BW) gain were similar among systems (0.690 kg BW day-1). However, the gain per area differed, where the LPF was 28% greater than the others, which presented an average of 932 kg BW ha-1. FA and FAR (forage accumulation rate) did not differ between CL and CLF, but both were 21% greater than L and LF. Similar pattern was observed in total forage accumulation, where crop-preceded systems (CL and CLF) were 22% greater than L and LF. Leaf ratio and leaf:non-leaf ratio were not affected by systems, averaging 90.4 g g-1 MS and 14.6 g g-1 MS. Crude protein (CP) was affected by the systems, with similar concentrations in CLF and LF. However, CLF presented CP 8% greater than L and 14% greater than CL. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were not affected by the systems, averaging 59.2 and 27.5%, respectively. Forage total carbon (TC), nitrogen stock (N) and total carbon accumulation (ATC) were affected by systems. The ATC in CL was similar to CLF and 23% greater than the average of L and LF systems. In addition, the TC in CL was 11% greater than L and CLF and 33% greater than LF. The N stock in the LF was 22% lesser than the average of the L, CL and CLF systems (78.9 kg N ha-1). Based on our results, integrated systems are alternatives for intensifying pasture animal production and the addition of the forestry component contributes to animal productivity and carbon stock, ensuring better nutritional value and sustainability of the production system.