Genetic parameters and purebred–crossbred genetic correlations for growth, meat quality, and carcass traits in pigs

Abstract

Growth, meat quality, and carcass traits are of economic importance in swine breeding. Understanding their genetic basis in purebred (PB) and commercial crossbred (CB) pigs is necessary for a successful breeding program because, although the breeding goal is to improve crossbred performance, phenotype collection and selection are usually carried out in purebred populations housed in biosecure nucleus herds. Thus, selection is indirect and accuracy of selection depends on the genetic correlation between PB and CB performance (r_pc). The objectives of this study were to 1) estimate genetic parameters for growth, meat quality, and carcass traits in a PB sire line and related commercial CB pigs, and 2) estimate the corresponding genetic correlations between purebred and crossbred performance (r_pc). Both objectives were investigated by using pedigree information only (PBLUP) and by combining pedigree and genomic information in a single-step procedure (ssGBLUP). Growth rate showed moderate estimates of heritability for both PB and CB based on PBLUP, while estimates were higher in CB based on ssGBLUP. Heritability estimates for meat quality traits were diverse and slightly different based on PB and CB data with both methods. Carcass traits had higher heritability estimates based on PB compared to CB data based on PBLUP and slightly higher estimates for CB data based on ssGBLUP. A wide range of estimates of genetic correlations were obtained among traits within the PB and CB data. In the PB population, estimates of heritabilities and genetic correlations were similar based on PBLUP and ssGBLUP for all traits, while based on the CB data, ssGBLUP resulted in different estimates of genetic parameters with lower standard errors. With some exceptions, estimates of r_pc were moderate to high. The standard error on the r_pc estimates were generally large when based on PBLUP due to limited sample size, especially for crossbreds. In contrast, estimates of r_pc based on ssGBLUP were not only more precise, but also more consistent among pairs of traits, considering their genetic correlations within the PB and CB data. The wide range of estimates of r_pc (less than 0.70 for 7 out of 13 traits) indicates that the use of CB phenotypes recorded on commercial farms, along with genomic information, for selection in the PB population has potential to increase genetic progress of CB performance.