Some behaviors of pigs that are not expressed in the wild state or are observed in a small minority of individuals after groups of pigs are mixed have been reported to indicate poor welfare. A GWAS analysis was performed by measuring the frequency and duration of the four ethological traits and using the mlma command provided by the genome-wide complex trait analysis (GCTA). The positional candidate genes on significantly identified single nucleotide polymorphism (SNP) markers were identified by using the dbSNP provided by the National Center for Biotechnology Information (NCBI). When the GWAS analysis was applied the 43,565 (of the purebred Landrace population) and 41,700 (of the purebred Yorkshire population) SNP markers, 1, 2, and 1 significant SNP markers were identified for the traits of feeding frequency (LOC110262254), locomotion time (LOC110260361), and locomotion frequency (LOC110260361) of the purebred Landrace population, respectively. Meanwhile, 1 and 7 significant SNP markers were identified for the traits of drinking time (LOC 110260090) and feeding frequency (MAP3K19; LOC110257013; ACMSD; TMEM163; RAB3GAP1) of the purebred Yorkshire population, respectively. The results of this study may suggest that the GWAS analysis of the ethological traits of purebred Landrace and Yorkshire populations could be used to perform a GWAS analysis on non-economic traits, and the results can thus be provided as basic data for GWAS analyses of other non-economic traits in the future.

According to Livestock Inspection Standards, the piglets enter the feedlot at approximately 30 kg, and the inspection starts after the preliminary feeding period. The reason for applying the preliminary feeding period is to select inspection piglets with no diseases after the complete growth of the internal organs until 10 weeks of age. Furthermore, the age of 10 week is the time when the muscle fibers grow to their maximum size and the piglets are prepared for fat deposition at the later fattening period. In the study, a genome-wide association study (GWAS) was performed through the mlma command of the genome-wide complex trait analysis (GCTA) program with 703 purebred Landrace population, and the candidate genes associated with the weight of 10 week were searched. The GWAS identified 3 single nucleotide polymorphism (SNP) markers, which have a significant genome-wide suggestive level, on chromosome 6 (DIAS0002615; p-value=1.62×10-6, MARC0083933; p-value=4.94×10-6, ASGA0028717; p-value=5.40×10-6). The 2 genes (Ubiquitin protein ligase E3 component n-recognin 4; UBR4, WD and tetratricopeptide repeats 1; WDTC1) in which these 3 SNP markers are located are positional candidate genes of the weight of 10 week of the purebred Landrace population. 2 candidate genes have been reported to be associated with fattening. Therefore, the positional candidate genes in this study, UBR4 and WDTC1, are expected to be usable as genes for traits associated with the weight of 10 week weight and fattening through additional experimental research with other population.

This study was conducted to find out that how much does it effects as it considered not only animal additive genetic effect but also maternal genetic effect for improving litter traits of pigs. The data of 10,836 records on 2,636 sows in Landrace and 14,463 records on sows in Yorkshire were analyzed which had been measured from 1998 to July 2017 in a nucleus herd of pig population. The traits used on this analysis were total number of born with (TNB2) and without mummy (TNB1) and number of born alive (NBA). Two different multivariate animal mixed models were considered and compared of variance components estimated from these models. The one (Model 1) was set up with assumed to parity, return events and batch effects as fixed and service sire, permanent environment and animal additive genetic effects as random. The other (Model 2) was same with Model 1 except considering maternal additive genetic effects as random. (Co)variance for random effects and genetic parameters were estimated using restricted maximum likelihood method and breeding values as best linear unbiased prediction were estimated using preconditioned conjugate gradient algorithm on each model and breed. From these models, heritability estimates for NBA were about 0.10 and 0.11 on both models in Landrace and Yorkshire, respectively. Forthermore, it was estimated that there were little variations in the maternal genetic effects with roughly 1~2% of total variation. Result from comparing estimated breeding values for each trait between each model, ranking of genetic capability through total breeding values on model 1 and on model 2 showed highly correlated with more than 0.92. Consequently, for improving litter traits, selection based on breeding values by direct genetic effects without considering maternal genetic effects were reccommendable.

돼지의 생시체중은 생존율과 폐사율에 밀접한 관련이 있어 양돈산업에서 자돈 관리와 직결된 중요한 경제형질이다. 본 연구는 Genome-Wide Association Study(GWAS) 분석을 통해 순종 랜드레이스의 생 시체중과 관련된 위치상 후보유전자 탐색을 실시하였다. 생시체중의 유의적 관련 분석 결과, genomewide suggestive level에서 유의성 있는 single nucleotide polymorphism(SNP) marker는 3번 염색체 (ASGA0098921, P=2.41×10-5)와 4번 염색체(H3GA0013451, P=2.47×10-5)에서 각각 1개씩 동정되었다. 이들 SNP marker가 위치한 3개의 유전자(LOC110260055, LOC100156472, LOC100157689)들은 순종 랜드레이스 생시체중의 위치상 후보 유전자이며, 이들 유전자 정보를 이용해서 순종 랜드레이스 생시 체중을 선발할 수 있는 기초 연구 자료가 될 것으로 사료된다.

돼지의 체장, 체폭, 체중 등의 연속적인 변이를 가지는 양적형질에 속하는 형질인 성장형질은 양돈업에 있어서 생산성과 수익성에 직결된 중요한 경제 형질이다. 성장형질로는 일당증체량, 등지방두께, 등심단면적 및 도체품질 등이 있으며, 그중에서 등심단면적과 관련이 있는 후보 유전자를 Genome-wide 수준에서 선발하기 위하여 Illumina 사의 Porcine SNP 60K chip을 이용하여 순종 Landrace 집단(수컷 : 50두, 암컷 : 440두)을 분석하였다. Plink program을 이용하여 filtering 과정을 거쳐 최종적으로 31,960개의 SNP marker를 선별하였으며, Genome-wide 임계수준을 bonferroni correction (i.e.1/31957=3.12×10-5)을 이용해서 결정했을 때, SSC16에서 유의성 있는 4개의 SNP marker들을 발견하였다. 이 중 가장 유의성 있는 SNP marker인 DRGA0016148(P=1.38×10-5)와 근접한 후보유전자로 PDE4D를 선정하였고, PDE4D에서 2개(g.9870 T>C, g3976 C>T)의 SNP를 탐색하였다. 본 연구에서는 Genome-wide association study (GWAS)를 이용하여 등심단면적과 관련성이 있는 SNP를 선발하여, 등심단면적과 후보유전자 PDE4D와의 관련성을 규명하고자 연구를 실시하였으나, PDE4D g.9870 T>C 에서는 Hardy-weinberg equilibrium P-value 0.7581로 음의 상관관계를 나타내었으며, PDE4D g.3976 C>T에서는 모두 호모타입이 확인되었다.