Avaliação meta-analítica dos efeitos da suplementação alimentar sobre o consumo de forragem de bovinos de corte em pastejo

Abstract

Forage consumption is the most important factor in the beef cattle production managed to pasture, being the basis of the diet. Knowing the factors that affect this parameter helps decision making. The objective in this study was to quantify, by means of a meta-analytical evaluation, the factors that affecting consumption of dry matter pasture (CDMp) and total (CDMt) of growing cattle in the pasture beef cattle production systems in tropical conditions, and create equations that would allow such estimation. The database was composed of articles from journals classified in QUALIS Capes 2014, which 39 are from 9 journals. For the CDMp and CDMt consumption model of the experimental units receiving concentrated supplementation, 1270 experimental units were evaluated in 118 treatment averages. Concentrated supplementation, when evaluated the consumption of dry matter supplement (CDMs) and non-protein fraction of the supplement (NPFs), they exercise substitute effect on CDMp (g/kg/animal/day), being more pronounced for animals in rotational grazing method, for CDMs with a replacement rate of 11.6% per kg CDMs and at the continuous rate at 8.1% per kg CDMs and for NPFs with a replacement rate of 24.7% per kg CDMs in rotated and in continuous rate of 11.4% per kg CDMs. Pasture crude protein (PasCP) exerts a quadratic effect on CDMp, being the CDMp increasing up to 13% PasCP and then starting to fall. The stocking method rotated CDMp is larger when compared to the continuous stoc king method. The rotational grazing method did not suffered influence CDMs and NPFs affecting CDMt. But the continuous grazing method had positive effects with the CDMs and NPFs. There was an additive substitute effect, since the CDMt increased, but it was not greater than the amount of supplement ingested. The increase in CDMt was 5% and 7% for NPFs and CDMs, respectively. There was a quadratic effect of the PasCP in CDMt, with a maximum point CDMt the PasCP of 13%, after this value the CDMt tends to fall. The main characteristic that causes the substitution is the NPFs, so that the increase of the crude protein supplementation does not cause substitution of the forage consumption. The forage crude protein content affects positively (with quadratic effect, provoking a significant increase to a certain point, with maximum to 13% of crude protein in the forage) the pasture and total dry matter consumption.