Prolactin is an anterior pituitary hormone involved in various physiological phenomenon including reproduction. The prolactin receptor (PRLR) is detected in diverse tissues such as brain, ovary, placenta and uterus in several mammalian species. A total of 227 pigs [Korean native pigs (KNP) 27; Landrace pigs 29; Korean native pigs x Landrace F1 91; Nanchuckmacdon pigs 80] were used to investigate the allele frequency difference of the prolactin receptor (PRLR) gene among the four pig lines. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with Alu I restriction enzyme was used to determine the genotypes of PRLR. Frequencies of PRLR alleles among the four different pig lines were not significantly different (Chi-square=3.94, DF=3, P=0.27). A total of 40 Nanchuckmacdon pigs were used to investigate the effect of the prolactin receptor (PRLR) gene on total number of piglets born (TNB), number of piglets of alive (NBA) using general linear model implemented in MINITAB software. For TNB, the AB genotype had higher genotypic value (10.61) than the values of AA (9.83) and BB (10.30). Likewise, the AB genotype had higher genotypic value (8.96) than the values of AA (8.18) and BB (8.90) for NBA. However, these associations of the PRLR gene with TNB and NBA were not statistically significant. In conclusion, it is necessary to increase the sample size for investigating the effect of the PRLR gene on TNB and NBA in pigs.

Blood types in pigs are divided into two types, A and O type. It is important to select and breed O-type pigs that have no hematologic rejection, because the blood type of the donor is an important factor causing immune rejection in xenotransplantation. Therefore, the gene that determines the blood type is GGTA1(glycoprotein, alpha-1,3-galactosyltransferase 1), which generally belongs to the ABO blood group. This study was carried out to develop a simple and accurate method by analyzing the structure of GGTA1 gene which determines blood type. A primer was designed to allow easy identification of the blood type of the target in the first and second deletion regions of intron 7 to distinguish between the A and O genotypes. That is, for the purpose of identifying the blood type using length difference after the PCR, the forward and reverse primers were designed in the highly conservative region. As a result, a pair of primers were prepared and PCR amplification was performed to distinguish three types of genotypes, AA, AO, and OO, using the length difference by electrophoresis. Using the above primers, the parents and their offspring were compared with each other to confirm the correct genetic pattern. And, in four pig breeds, the genes were amplified and the genotype could be correctly identified. In this study, we could diagnose the blood type of AA, AO, OO genotype of pigs by using primer of INDEL region. Especially, since it is possible to diagnose the genotype by the length difference, it is possible to diagnose it quickly and accurately from the gene amplification to the genotype reading

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.

Precise, rapid and simple methods for species identification in animals are among the most important techniques in the livestock industry and research fields including meat classification. In this study, polymerase chain reaction (PCR) based molecular identification using inter species polymorphisms were examined by PCR-restriction fragment length polymorphism (RFLP) analysis for mitochondrial DNA (mtDNA) cytochrome b (CYTB) gene sequences among four mammalian livestock animals (cattle, horse, goat and pig). The results from PCR-RFLP analysis using the AluI restriction enzyme were also provided for the species-specific band patterns among CYTB gene sequences in these four species. The AluI-digestion for CYTB genes provided interesting migration patterns differentially displayed according to each species. Cattle and horse had one AluI-recognition site at different nucleotide positions and their AluI-digested fragments showed different band patterns on the gels. Pig had two AluI-recognition sites within the amplified CYTB sequences and produced three bands on the gels. Goat had no AluI-recognition site and was located at the same position as the uncut PCR product. The results showed the species-specific band patterns on a single gel among the four livestock animal species by AluI-RFLP. In addition, the results from blind tests for the meat samples collected from providers without any records showed the identical information on the species recorded by observing their phenotypes before slaughter. The application of this PCR-RFLP method can be useful and provide rapid, simple, and clear information regarding species identification for various tissue samples originating from tested livestock species.

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.