Acúmulo de forragem e desempenho animal em pastos de capim-mombaça sob doses de nitrogênio e pastejo intermitente

Abstract

The objective of this work was to evaluate forage accumulation, structural characteristics of the canopy and animal production in pastures of Mombaça grass receiving doses of nitrogen and managed under intermittent grazing. The experimental design was a randomized block design with three nitrogen doses and four area replicates. Nitrogen doses were 100, 200 and 300 kg ha1 per year, in the form of urea. The grazing method used was intermittent, with a variable stocking rate. The animals entered on the paddocks when the canopy reached 80-90 cm of height. The animals were removed from the paddocks when the height of post-grazing residue reached 45-50 cm. Canopy heights, forage mass and their components were evaluated in pre and post-grazing. The accumulation rate was calculated by the difference between the postgrazing and pre-grazing samplings. Stratified samples were collected to determine the canopy forage density. The stocking rate adjustment was performed as the paddock approached the established height targets. Every 28 days, the animals were weighed to evaluate the average daily gain and gain per area. Higher forage accumulation rates (84.5 kg ha-1 per day), average daily gain (0.760 kg animal-1 per day) and gain per area (1,542 kg PV ha-1 per period) were observed in pastures fertilized with 300 kg ha-1. The use of 100, 200 or 300 kg ha-1 of nitrogen in pastures of Mombaça grass is an alternative for the maintenance of pastures and reach of larger forage and animal production. The choice of the best dose will depend on the objectives of the production system, combining the biological and economic response.