Associação genética entre eficiência alimentar e as características de carcaça em bovinos da raça Nelore

Abstract

In view of the concern to maximize the productivity of beef cattle, with lower production cost, the residual feed intake - CAR is the main measure to be used for the selection of animals efficient in the use of food. The important thing to note is that the selection of these animals is necessary, but there can be no antagonism between the CAR and other traits of interest in production, such as adequate fat deposition and carcass yield. In this sense, this study aimed to verify the genetic association between the traits related to feed efficiency and the carcass traits of Nellore cattle. The information of 7,808 males and females Nellore, pure of origin (PO), were consider, evaluated in 142 tests of feeding efficiency carried out in the period from 2011 to 2020, in 15 farms participating in the program Nellore Brazil of the National Association of Breeders and Researchers - NABR. The traits of residual feed intake - RFI, dry matter intake - DMI, rib eye area - REA, carcass finish - CF and marbling - MAR were evaluate. Feed efficiency and carcass traits were also evaluate only in Nellore females. The estimated of the components of variances and covariance, as well as, of heritabilities and genetic correlations were obtain through bicharacteristic analyzes under an animal model, considering the methodology of Maximum Derivative Free Restricted Likelihood. It was check that the heritability characteristics were moderate for the characteristics of RFI (0.22) and DMI (0.29), which proves the existence of genetic variability in the evaluated Nellore population. It was observe that as a genetic correlation were of low magnitude, with values close to zero, for all traits,except between RFI and REA (-0.11). In general, these results infer that the selection for RFI and DMI does not cause genetic damage to the carcass traits in Nellore cattle. However, when evaluating the genetic associations of RFI and DMI with carcass traits, considering the population of females, there were an increase in the estimate of genetic correlation with RFI and DMI, although it is still a favorable genetic association of low magnitude (- 0.30). There was also an increase in the genetic association of REA with the RFI(-0.21), which indicates that there are some favorable response from the selection of more efficient animals with the improvement of the carcass yield, however, it must be emphasized, that such changes are not very significant. It can be conclude that the direct selection for residual feed intake (RFI) and dry matter intake (DMI) will not influence the deposition of subcutaneous fat (CF), marbling (MAR), and rib eye area (REA) of Nellore cattle. However, the selection for the RFI may be generate some favorable response in the deposition of intramuscular fat (MAR) and in rib eye area (REA) of Nellore females.