Estimativas de parâmetros genéticos e fenotípicos para características de crescimento e carcaça de suínos da raça duroc

Abstract

Pig breeding in the world represents one of the main sources of animal protein for human consumption. In this sense, animal breeding studies are needed to improve economically relevant traits related to the quantity and quality of products. The objective of this study was to estimate genetic parameters for body weights, average daily weight gain at different ages and carcass traits to define new selection criteria in Duroc pigs. A database with records from a core herd of the Duroc breed was used breed belonging to a pig genetic improvement company AcuFastTM and selected for growth and carcass quality was used. The traits evaluated were body weight at 70, 100, and 155 days of age (P70, P100, and P155); average daily weight gain at the different ages (GMD1, GMD2, and GMD3), fat thickness (FAT), loin depth (LD), and intramuscular fat content (IMF). To estimate genetic parameters, the restricted maximum likelihood methodology was used, under an animal model, in single- and two-trait analyses. In single-trait analyses, the influences of the random maternal genetic and maternal permanent environment effects were tested. To define the most appropriate models, the likelihood ratio test was used. After testing, the direct and maternal genetic effects and the maternal permanent environment effect were considered in the P70, P100 and P155 model. Then, two-trait analyzes were conducted to estimate genetic, environmental and phenotypic correlations between the studied traits. The heritability estimates ranged from for 0.15±0.03 (P70) to 0.58±0.04 (EG). Maternal heritability ranged from 0.02±0.01 (P155) to 0.04±0.02 (P70). The proportion of the maternal permanent environment effect ranged from 0.07±0.01 (P155) to 0.11±0.02 (P70). Genetic correlations (p<0,01) ranged from 0.32±0.07 (GMD2 x PGI) to 0.87±0.03 (P100 x GMD1). The estimated heritability coefficients for the studied traits in Duroc pigs demonstrate that selection for body weight, weight gain and carcass traits is viable. It can be considered that the use of GMD2 may promote direct gains in the trait itself, as well as for the other weights and weight gains. Regarding the carcass traits, selection for GMD2 will promote indirect and favorable gains in LD and IMF; however, it should be performed with caution, as there is a chance of increasing the percentage of fat in the carcass. Direct selection for LD does not appear to affect FAT and IMF, a desirable situation if the objective is to increase the amount of meat produced without increasing the percentage of fat.