Informações genômicas na avaliação genética de características de crescimento em bovinos Senepol

Abstract

Senepol cattle, classified as an adapted taurine breed, stands out for associating adaptability to tropical environment and high fertility rates, maternal ability and meat tenderness. However, there are no studies in the world literature that have presented the components of (co)variance and genetic parameters using genomic information for growth traits in the Senepol breed, as well as the impact of genomics on estimates and predictions. Therefore, the aim of this study is to evaluate the effects of including genomic information in the estimation of (co)variance components, genetic parameters and prediction of genetic values for growth traits in Senepol cattle. Phenotypes from 73,547 and genotypes from 6,463 Senepol cattle were used for birth weight (BW), weight at 120 days (W120), weaning weight (WW), yearling weight (YW) and post-weaning weight gain (PWG). Covariance components and genetic parameters were estimated using conventional BLUP and single-step genomic BLUP (ssGBLUP) in uni- and bi- trait analyzes with all possible combinations between traits. In addition, the estimation of genetic values was carried out based on bi-trait analyzes of each weight with YW with or without the inclusion of genomics. The prediction ability of the analyzes was performed using linear regression method (LR), in two validation scenarios with complete and reduced databases, the first (I) with the removal of phenotypes from young animals and the second (II) with the removal of phenotypes from genotyped bulls and their progenies. Heritability estimates ranged from 0.05 to 0.30 and from 0.05 to 0.29 for analyzes without and with genomics, respectively. The inclusion of genomics in the model did not cause major changes in the values of variances, heritabilities and correlations estimates for any of the traits evaluated. YW was the trait that presented the highest heritability estimated, indicating a greater response to selection when compared to other traits. The genetic correlations estimates were all positive between the traits, ranging from 0.19 to 0.95, indicating that selection for weight at a certain age will influence, in the same direction, weight at other ages. Regarding predictions of genetic values, the inclusion of genomics in the analyzes led to an increase of, on average, 5% and 11% in accuracy values in scenarios I and II, respectively. Furthermore, the inclusion of genomics also provided an increase in correlations between complete and reduced breeding value and reduced prediction bias in both validation scenarios. YW presented the highest accuracy values, which would provide a greater response to selection in relation to the other traits evaluated. The inclusion of genomics has little influence on the heritability values of Senepol cattle but provides gains in accuracy for growth traits, providing greater genetic gains related to genomic selection. Indirect genetic gains for weight can be obtained through selection and YW would provide the greatest response to selection in the Senepol cattle.