Avaliação do componente genético na expressão fenotípica de características de eficiência alimentar de bovinos da raça Nelore

Abstract

The objective of this study was to evaluate the effect of the genetic component in the phenotypic expression of dry matter intake (DMI) and the residual feed intake (RFI) of Nellore cattle submitted to the food efficiency test at Rancho da Matinha farm in Uberaba, Minas Gerais. In the EA test, females used data from 143 animals, daughters from 11 bulls and in the EA Test of males considered information of 146 animals, children of 24 bulls. In order to verify the contribution of the genetic component in the productive performance of the evaluated animals, the predictions of the DEPs of the bulls (parents of the animals in evaluation), provided by the National Association of Breeders and Researchers (ANCP), were verified. The genetic groups or classes of DEPs for the characteristics of RFI and DMI were defined according to the values of the DEPs: class of negative (class 1), median (class 2) and positive (class 3). To verify the effects of the genetic groups on the food efficiency characteristics, analyzes of variance and comparison of means by Tukey's test were performed. It was verified that there was statistical difference between the phenotypic means for RFI and DMI in genetic groups 1 and 3. It was observed that in the lot of females had a significant difference of RFI (0.376 kg DM/day -1 to -0.403 kg DM/day -1) and DMI (8.748 kg DM/day -1.7.969 kg DM/day -1 In the batch of males, a significant difference of RFI (0.273 kg DM/day-1 at -0.243 kg DM/day-1) and DMI (7.679 kg DM/day-1 at 7.230 kg DM/day-1) was also observed between classes 1 and 3. These results showed that expressive genetic gains will be observed when practicing the selection of reproducers through the DEPs for RFI and DMI (more negative DEPs are favorable). The genetic component of the parents influenced the phenotypic expression of the progenies for the characteristics related to food efficiency. The selection of animals with negative DEPs for RFI and DMI led to the production of more efficient animals (males and females), due to the reduction of feed consumption, in confinement.