Abstract
The objective of this study was to find out candidate genes associated with litter size trait in pigs of inbred Large Yorkshire and Landrace populations. 86 sows were screened for candidate genotypes along with litter size data recordings. Association of litter size with genotypes of candidate genes were investigated to verify the usefulness of each gene's genotypes as markers for the trait. For the lines of Large Yorkshire, PRLR3 and RBP4 genes were genotyped. Frequency distribution of PRLR3 with genotypes AA, AB and BB were each 0.14, 0.44 and 0.42. And the average litter size by PRLR3 genotypes were 8.83, 10.81 and 10.70 piglets per litter, the average estimated breeding values of which were 0.243, 0.332, 0.365, respectively for AA, AB and BB genotypes. Genotypic frequencies of RBP4 by AA, AB and BB genotypes were 0.10, 0.44 and 0.46. The average litter size by genotypes of RBP4 were 10.40, 10.57 and 10.35 piglets per litter and their corresponding average estimated breeding values were 0.451, 0.353 and 0.261, respectively for genotypes AA, AB and BB. Significance in differences among genotypes were not observed, but B allele of RBP4 seems to be associated with litter size. In Landrace lines, frequencies of RBP4 genotypes, AA, AB and BB were 0.29, 0.55 and 0.16. And the average litter size of these genotypes were 10.50, 11.08 and 11.00 piglets per litter. The corresponding averages of estimated breeding values of each genotypes were 0.172, 0.135 and 0.104. In Landrace lines, allele A was more likely to be associated with litter size, even if differences among average litter size were not significant. We conclude that genotyping of two candidate genes is a helpful tool to identify genetic potentials of litter size in pigs.
본 연구는 국립축산과학원에서 조성한 대요크샤종 및 랜드레이스종 근교계통돈 86두에 대해 산지수에 관여하는 유전자로 알려진 PRLR3, FSR, RBP4 후보유전자 3종의 유전적 다형성을 분석하여 이들 후보유전자와 총산자수의 표현형 및 육종가 간의 연관성을 검증함으로써 경제형질과 관련된 유용표지인자 활용 방법을 개발하고자 수행하여 유전적 다형성을 확인하였다. 대요크샤종에서는 PRLR3, RBP4 후보유전자의 AA형 유전자 빈도가 낮게 나타났으나 이들 모두 다형성을 보였고, 이중 PRLR3 후 보유전자는 B대립유전자가 유의적인(p<0.05) 연관성을 가지고 있었으며, RBP4 후보유전자 역시 유의적인 차이는 없었지만 B대립유전자가 연관성을 가지고 있는 것으로 추정되었다. 랜드레이스종에서 PRLR과 FSR 후보유전자는 다형성이 나타나지 않았으며, RBP4 후보유전자에서 BB형 유전자 빈도가 낮게 나타났으나 다형성을 보였고, 유의적인 차이는 없었으나 A대립유전자가 총산지수의 표현형 및 육종가와 연관성을 가지고 있는 것으로 추정되었다. 본 연구 결과를 활용하여 유의적인 후보종돈을 선발할 경우 번식 능력의 향상에 효과적일 것으로 판단된다.