Estimação de parâmetros genéticos em suínos das raças Landrace e Large White

Abstract

Pig farming represents one of the most important livestock segments and is responsible for much of the protein consumed worldwide. The scientific and technological development was responsible for the evolution of this sector, being the selection process an efficient tool and used to change the allelic frequencies of a population to the desired direction. The objective of this study was to evaluate the fixed effects and estimate genetic parameter for average litter weight at birth (PMLN), average litter weight at weaning (PMLD) and weaning-conception interval (IDC) in Landrace and Large White pigs. Productive and reproductive data from herds belonging to a private breeding company located in Canada were used. The pedigree data were evaluated and renumbered by the CFC program. Data were analyzed using SAS by means of the least squares method for PMLN, PMLD and IDC. There was a significant influence (P <0.001) for the fixed effects of month and year of birth, herd, days at lactation (current and previous), number of live-born piglets, calving order and number of weaned piglets. For IDC, the covariates of average litter weight at birth and at weaning were also significant (P <0.001). The mean values observed for PMLN, PMLD and IDC in Landrace were equal to 1.51±0.25 kg, 68.21±18.37 kg and 5.75±1.27 days, respectively. For Large White animals, mean values of 1.38±0.22 kg, 69.51±17.61 kg and 4.74±1.08 days, respectively, were observed. The heritability (h²) and the proportion of permanent environmental effect (c²) estimates were obtained by means of the Wombat software in single-trait analyses, under an animal model. The estimates of h² for PMLN and PMLD in the two breeds varied from 0.21 to 0.41, being considered of moderate to high magnitude. Regarding the IDC, estimates of h2 for the Landrace and Large White breeds were of moderate magnitude, equal to 0.28 and 0.32, respectively. Estimates of c2 presented low magnitudes, ranging from 0.05 to 0.14. It can be concluded that the fixed effects tested should be included in the analysis model as important sources of non-genetic variation. The estimates of h2 observed could favorably favor the selection process conducted by the breeding program of the company for the traits studied in both breeds.