Growth traits, such as body weight, directly influence productivity and economic efficiency in the swine industry. In this study, we estimate heritability for body weight traits usinginformation from pedigree and genome-wide single nucleotide polymorphism (SNP) chip data. Four body weight phenotypes were measured in 1,105 F2 progeny from an intercross between Landrace and Jeju native black pigs. All experimental animals were subjected to genotypic analysis using PorcineSNP60K BeadChip platform, and 39,992 autosomal SNP markers filtered by quality control criteria were used to construct genomic relationship matrix for heritability estimation. Restricted maximum likelihood estimates of heritability were obtained using both genomic- and pedigree- relationship matrix in a linear mixed model. The heritability estimates using SNP information were smaller (0.36-0.55) than those which were estimated using pedigree information (0.62-0.97). To investigate effect of common environment, such as maternal effect, on heritability estimation, we included maternal effect as an additional random effect term in the linear mixed model analysis. We detected substantial proportions of phenotypic variance components were explained by maternal effect. And the heritability estimates using both pedigree and SNP information were decreased. Therefore, heritability estimates must be interpreted cautiously when there are obvious common environmental variance components.

This study tested the association between genotypes of the single nucleotide polymorphism (SNP) marker, rs81437607 and capric acid (FA_C10_0) compositions in longissimus dorsi muscle in pigs. Eighteen fatty acid (FA) compositions were measured in a total of 974 F2 animals among 1,106 F2 progeny produced between Landrace and Jeju Black Pig (JBP). Among FA compositions tested, we identified a cluster of highly significant SNPs for capric acid compositions on 58 Mb position of Sus scrofa chromosome 12 (SSC12) using genome-wide association study (GWAS) with F2 genotypes from SNP panel analysis. GWAS results showed that the rs81437607 was the highest trait-related SNP marker with capric acid levels. Three genotypes (C/C, C/T and T/T) of rs81437607 marker were found in F2 population by further pyrosequencing. Association analysis results showed the significant differences between rs81437607 genotypes and capric acid compositions (P<0.05). The F2 pigs harboring rs81437607 C/C (0.119±0.002%) and C/T (0.116±0.002%) genotypes showed additively higher levels of capric acid content than those of T/T homozygotes (0.109±0.002%) (P=1.30×10-12). These results suggested that the genetic variations of rs81437607 may be helpful to find causative variants and assist as molecular genetic markers for improving the capric acid contents in longissimus dorsi muscle in pigs.

This study was carried out to examine a molecular marker system for parentage test in Jeju Black cattle (JBC). Based on the preliminarily studies, we finally selected for construction of a novel genetic marker system for molecular traceability, identity test, breed certification, and parentage test in JBC and its related industrial populations. The genetic marker system had eight MS markers, five indel markers, and two single nucleotide polymorphisms (SNPs; g.G299T and g.del310G) within MC1R gene which is critical to verify the breed specific genotypes for coat color of JBC differing from those of exotic black cattle breeds such as Holstein and Angus. The results showed lower level of a combined non-exclusion probability for second parent (NE-P2) of 4.1202×10-4 than those previously recommended by International Society of Animal Genetics (ISAG) of 5.000×10-4 for parentage, and a combined non-exclusion probability for sib identity (NE-SI) of 2.679×10-5. Parentage analysis has been successfully identified the JBC offspring in the indigenous population and cattle farms used the certified AI semens for production using the JBC-derived offspring for commercial beef. This combined molecular marker system will be helpful to supply genetic information for parentage test and traceability and to develop the molecular breeding system for improvement of animal productivity in JBC population.