Desempenho de novilhos mestiços nelore suplementados em pastagem com diferentes níveis de concentrado no período seco do ano

Abstract

In Brazil, the fattening of suplemented grazing animals in the last years accounted for most of the finishing animals in this time of the year. This work had the objective to evaluate the effect of increasing levels of concentrate in the fattening of crossbreed bullocks of Nelore breed grazing suplemented Brachiaria brizanta cv. Marandu pasture in the dry period of the year. The experiment was conducted in the Beef Cattle Division of the Animal Science Department at Universidade Federal de Lavras, Minas Gerais, from June to September of 2001. It was used 24 crossbreed Nelore cattle, males, not castrated, averaging 30 months old and with the means of live weight of 295 Kg. During the experimental period, the animals were housed in a sealed pasture of Brachiária brizanta cv. Marandu, with an area of 11,50 ha and the average availability of 7,635 and 3,495 kgDM/ha at the begining and at the end of the period, respectively. The treatments were constituted of increasing levels of concentrate calculated as percentage of the body live weight, as follow: T1 - 0%; T2 - 0,4%; T3 - 0,8%; T4 - 1,2%. The experimental design was a randomized complete block design with the initial live weight as the blocking factor: 6 blocks, 4 treatments, totaling 24 experimental units. For the data analysis the statistical software SISVAR was used (Variance Analysis System of Balanced Data). There was significant effect (with linear adjustment) of the concentrate levels in the daily weight gain (P < 0,05), with point of maximum of 0,87% of BLW. Based on the data analysis, it was concluded that the finishing of Nelore bullocks, grazing suplementated Brachiaria brizanta cv. Marandu pasture, is technically and economically viable with better results at the level of 0,76% of BLW.