Composição química da dieta e desempenho bioeconômico de ovinos pastejando capim-aruana sob quatro níveis de suplementação concentrada

Abstract

The present study was conducted with the objective of evaluating the chemical composition and carbohydrate fractionation of the sheep diet; As well as the ingestive behavior, the productive performance, the carcass characteristics of these sheep and the bioeconomic analysis in systems of sheep termination in aruana grass under increasing levels of concentrated supplementation. Four doses of supplement concentrate were compared 0.0; 0.6; 1.2 and 1.8% of the animals body weight. A total of 43 Morada Nova ewes with mean age of seven months, mean initial weight of 15.28 ± 1.24 kg, male, not castrated, being 24 test animals and 19 balance animals used when necessary to ensure the reduction of vegetation to a residual leaf area Index of 1.0. The design used for the chemical composition and carbohydrate fractionation was completely randomized in a factorial arrangement of 4 x 2 (four levels of supplementation and two days of grazing) with five replications. For the other trials the design was entirely with four levels of supplementation and five replicates, for the behavioral test and six replicates for the trials of productive performance and carcass characteristics. Crude protein content was affected (p <0.05) both by supplementation levels and day of grazing. The greatest difference between supplementation levels was observed when comparing the crude protein content of the pasture samples at the 1.8% BW level (17.54%) and the pastures at the 0.0 and 0.6 level % Of the BW (15.15 and 15.50%, respectively). The forage harvested on the first day of grazing had a mean NDF content of 65.91%, lower than the average NDF content of that harvested on the third day of grazing, which was 70.22%. The levels of supplementation of 0.0 and 0.6% of BW had higher total carbohydrate levels (70.98 and 71.11%) at supplementation level 1.8% of BW (68.35%). The sheep that were supplemented with 1.8% of the BW were the ones that obtained the best gains in weight and carcass yield. Analyzing the activity profit (R$/month) of the animals that received concentrated supplementation in their diet, it was noticed that there was decrease in the profit as the level of supplementation in the diet increased. When comparing the gross margin, net margin and profit from the sale of commercial cuts in relation to the sale of the carcass, there were no large differences between values. The increase of the concentrated supplementation in the diet of the sheep causes an increase in 16 the crude protein intake and reduction in the total carbohydrate intake, characterizing a selectivity at the time of the grazing, due to this, it is recommended that 1,2% of supplementation in relation to the weight Body. As well, it allows to obtain a behavior with lower grazing times, a productive performance with higher weight gains and stocking rates, such as, carcasses with higher weights and with better yields. Economic projections indicate that when the farmer trades live animals, the finishing system exclusively on pasture (0.0% supplement) is the only viable with the selling price currently practiced in the market, but when the producer slaughters and markets the carcasses by adding In this way product value, the termination systems of 0.0 and 0.6% of supplementation present the best economic-financial indices, providing greater profitability, and can even be adopted a sale price below market price, mainly in the system of termination without supplementation.