Objective  To estimate the genetic parameters of three economic traits in a long-term selection population, analyze their genetic progress, and investigate the factors including long-term selection affecting the genetic parameters in the practical breeding population.

Method  A total of 15 760 growth performance records of Duroc pigs were collected in a core breeding field from 2003 to 2018. Using DMUAI module and DMU4 module of DMU software, a multi-trait animal model was used to estimate the genetic parameters and breeding values of three important economic traits. We estimated the genetic parameters of annual accumulative population to evaluate the change of genetic parameters during the long-term selection.

Result  The estimates of heritability for three important economic traits including age, backfat thickness and loin muscle area at 100 kg body weight were 0.354, 0.477 and 0.479, respectively. All three traits had medium-high heritability. There were low correlations among three economic traits. The genetic and phenotypic correlations ranged from −0.110 to 0.039 and from −0.076 to 0.082, respectively. Among three traits, age at 100 kg body weight had relatively greater genetic progress in long-term selection, while backfat thickness at 100 kg body weight and loin muscle area at 100 kg body weight had relatively less genetic progress. Furthermore, the additive genetic variance changed in different degrees for three economic traits by estimating the genetic parameters of the annual accumulative population.

Conclusion  These traits of this Duroc pig population had the medium-high estimates of heritability and low correlations. Moreover, long-term selection and introduction could lead to the changing of genetic parameters. Therefore, genetic parameters should be estimated timely to obtain accurate genetic evaluation for accelerating the genetic improvement in breeding practice.