Associações genéticas entre indicadores de eficiência alimentar e características de carcaça em bovinos da raça Senepol

Abstract

The aim of this work was to evaluate the influence of genetic selection for feed efficiency in carcass of Senepol cattle. Were used data collected from food efficiency indicators: gain to feed (EAT), feed conversion ratio (CAT), residual weight gain (GRES), residual intake and body weight gain (CGR) and residual feed intake (CAR); in addition to growth characteristics: final weight (PF), average daily gain (GMD), dry matter intake (CMS);

carcass traits: rib-eye area (AOL), backfat thickness (EGS), marbling score (MAR) and post- yearling slaughter conformation (CONF). Were used records of 1393 heifers evaluated

between the years 2009 to 2018. We adopted an animal model with fixed effect of contemporary group, formed by the edition of the test and farm of origin; linear effect of the age of the animal at the beginning of the test as covariate; in addition to random direct additive and residual genetic effects. The (co)variance components were estimated by Bayesian inference in uni and bivariate analyzes. In addition, the canonical correlations were obtained to estimate the influence ratio of the individual feed efficiency characteristics on the group of carcass traits and growth of the animals and vice versa. The results showed that food efficiency indicators derived from residues such as GRES, CGR and CAR responded well to genetic selection (h2 = 0.14 ± 0.06, 0.13 ± 0.06 and 0.2 ± 0.08 respectively), whereas those calculated as reasons such as EAT and CAT are not indicated for use in breeding programs because they are highly influenced by the environment (h2 = 0.08 ± 0.05 and 0.09 ± 0.05). The characteristics with the greatest impact on selection for food efficiency are the GMD, AOL and EGS, with a greater influence on growth and carcass of the GRES indicator, and lower on the CAR. Selection for feed efficiency will promote distinct effects on growth and carcass of animals. The CAR will promote greater reduction in food intake and greater fat finishing in the carcass, but there will also be a reduction in the growth and deposition of muscle tissue. The GRES, despite promoting the greatest weight gain and having little effect on the carcass of the animals, is linked to the higher consumption of food. Thus, the recommended indicator is the CGR for promoting the decrease in food consumption concomitant to the growth of the animals, with effects similar to the other indicators in the carcass of the animals.