Consumo observado e predito pelos sistemas nutricionais em bovinos de corte confinados

Abstract

The objective of this study was to compare the dry matter intake observed in Nellore heifers, Nellore bulls and Senepol bulls in feedlot, predicted by the nutritional systems BR-Corte (2010 and 2016) and NRC (2000 and 2016) and what model makes better predictions for these breeds and categories of beef cattle in feedlot. For this, three experiments were conducted from February to December 2017 at the Experimental Capim Branco Farm of the Universidade Federal de Uberlândia (UFU). In the first one, 24 Senepol bulls, not castrated with a mean initial weight of 368 kg and 16 months of age, were used. In the second trial, 47 Nellore bulls were used, not castrated with a mean initial weight of 413 kg and 19 months of age. In the third study, 24 Nelore heifers with mean initial weight of 300 kg and 23 months of age were used. The diets used were: roughage, corn silage, and concentrate, based on soybean meal, milled corn, urea and mineral nucleus, in the ratio of 60:40 for bulls (first and second study) and 80: 20 for heifers (third study). The treatments were the dry matter intake prediction equations according to NRC (2000), NRC (2016), BR-Corte (2010) and BR-Corte (2016) and the variables measured were individual dry matter use of the GrowSafe® electronic system and average daily gain. The accuracy and approximation of the estimates of dry matter intake by nutritional systems was adjusted by the simple linear regression model and the mean square error of prediction errors (QMEP). It was observed that for both groups there was no rejection of the null hypothesis (a = 0 and b = 1 P> 0.01), affirming that the NRC and BR-Corte models were adequate to estimate the dry matter consumption of the different categories and breeds of cattle in confinement. Through the QMEP and its decomposition, the models that made better predictions of consumption for Nellore heifers were BR-Corte 2010 and BR-Corte 2016 and for the Nelore and Senepol bulls it was the BR-Corte 2016. It was concluded that the BR- Cut 2016 was the most suitable model to estimate the dry matter intake, of these different categories and breeds, for accuracy and accuracy.