Fatty acid (FA) composition is one of the most important parameters for the assessment of meat quality in pigs. The FA composition in pork can also affect human health. Our aim was to identify quantitative trait loci (QTLs) and positional candidate genes affecting the FA profile of the longissimus dorsi muscle in a large F2 intercross between Landrace and Korean native pigs comprising 1105 F2 progeny by genome-wide association studies (GWAS) and post-GWAS high-resolution mapping analyses. We performed GWAS using the PorcineSNP60K BeadChip and a linear mixed model. Four genome-wide significant QTL regions in SSC8, SSC12, SSC14, and SSC16 were detected (p < 2.53 × 10−7). Several co-localizations of QTLs in SSC12 for oleic acid, linoleic acid, arachidonic acid, monounsaturated FAs, polyunsaturated FAs, and the polyunsaturated/saturated FA ratio were observed. To refine the QTL region in SSC12, a linkage and linkage disequilibrium analysis was applied and could narrow down the critical region to a 0.749 Mb region. Of the genes in this region, GAS7, MYH2, and MYH3 were identified as strong novel candidate genes based on further conditional association analyses. These findings provide a novel insight into the genetic basis of FA composition in pork and could contribute to the improvement of pork quality.
This study was conducted to investigate the ovarian cycle changes of the mare according to the season. Twenty four Jeju crossbred horses(Thoroughbred x Jeju horse) raised in Subtropical Livestock Research Institute, National Institute of Animal Science, RDA were used to identify follicles and corpus luteum with ultrasonography once a week(May 2016~June 2017). Blood samples of experimental horses were collected twice a week for analysis of P4 hormone levels. The mares were considered to have resumed ovarian cyclicity on the day of ovulation if they followed by regular ovarian cycles. Only 13 cases(61.9%) of the total 21cases showed normal ovarian cycle, and 8 cases (38.1%) showed delayed ovarian cycle. Three cases(16.7%) in October, 5 cases(27.8%) in November and 5 cases(27.8%) in December(27.8%) ceased the heat and the remaining 5 cases(27.8%) showed that the estrus was maintained in winter. Horses that stopped estrus ceased the heat until March of next year, and 27.8% were continued the heat during non-breeding season. Eleven cases(61.1%) of 18 cases in April and 2 cases(11.1%) of 18 cases in May returned the estrus.
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