Genetic polymorphisms and genetic effects of CAST gene in pigs.

Single-nucleotide polymorphisms of the porcine CAST gene were tested using PCR-SSCP. Genetic effects of the CAST gene on the meat quality and the backfat thickness were analyzed. On the basis of the published cDNA sequence (M20 160) of the porcine CAST gene, seven pairs of primers were designed, and two polymorphisms were found in the PCR products amplified with F1/ R1, and F6/R6 primers. A --> G transition at 317 site, G --> C transition at 2042 site were detected by sequencing the homozygotes. The results show that: Firstly, the Landrace, the Large White, and the Duroc breeds differ significantly (P < 0.01) in haplotype distribution from the Laiwu and the Yimeng breeds. Secondly, on the basis of the fixed effect model, significant differences (P < 0.05) were found in the tenderness and the backfat thickness among the different CAST haplotypes, whereas no significant differences (P > 0.05) existed in the pH, the temperature and the drip loss. Thirdly, using least square analysis, it was seen that significant differences (P < 0.05) were found in the temperature at 12 h and 24 h postmortem, the pH at 30 min and 1 h postmortem and drip loss among different pig breeds. Individuals of the BBCC and BBDD haplotypes had significantly less (P < 0.01) tenderness than those of the other haplotypes, and the pigs of the AACC and AADD haplotypes had significantly higher (P < 0.01) backfat thickness than those of the other haplotypes. These results suggest that the genotype has significant effects on the meat quality and the backfat thickness. CAST can be used in marker-assisted selection to provide significant improvements for meat quality and to accelerate the breeding progress.