Identification Of QTL For The Small Intestine Length In A Sutai Pig PoPulation Using A Genome-wide Association Study

Growth performance and feed conversion of pigs are affected by their digestive and absorptive abilities. Small intestine is one of the most important and also the longest organ of the digestive system. The digestion and absorption abilities of small intestine can directly affect the growth performance and the feed utilization of pigs. The small intestine can suffer pathological changes, such as short bowel syndrome in humans. Thus, the study of pig small intestine length can contribute not only to increase the economic values of pigs but also to provide an animal model of small intestine deseases in humans.The pig small intestine length has significantly positive correlations with some growth traits, such as birth weight, average daily gain and body length. Untill now, the genetic architecture of the small intestine length is still unclear, except few reported QTL. Genome-wide significant level QTL have been detectted on chromsomes2,4,7,8and12, and chromosome-wide significant QTL maps to chromsomes3,5,13,14,16and17.Sutai pig is a newly synthetic breed cultured from a cross between Duroc boars and Taihu sows. Sutai pigs have characteristics of high litter size, moderate growth speed and good meat quality. In this study, we measured the small intestine length and some growth traits of276Sutai pigs, and then used the CORR procedure of SAS to caculate the correlation coefficients between small intestine length and the growth traits. We also genotyped these animals with the Porcine60K SNP chips. To correct the effects of body weigth, slaughter batch, sex and kinship on small intestine length, a mixed linear model was fixed and the residual of small intestine length were caculated. The genome-wide association between SNP and the residual of small intestine length were performed using the GeneABEL package of R software.The results showed that the small intestine length had significantly possitive correlation with growth traits. We calculated the correlation coefficients between the small intestine length and body weight at slaughter (0.45), body length (0.39), body slant length (0.45), birth weight (0.30), average daily gain from birth to120-day (0.33), average daily gain from birth to240-day (0.45), average daily gain from120-day to240-day (0.40), body weight at120-day (0.33). Three chromosome regions were found to be significantly associated with the small intestine length. ALGA0102786at46.41Mb is the most significant SNP on chromosome16. It explain6.86%of phenotypic variance and the substitution effect is68.58cm. ASGA0025102at21.65Mb is the most significant SNP on chromsome5. It explained7.86%of phenotypic variance and the substitution effect is63.10cm. ALGA0114359at5.92Mb is the most significant marker on chromsome8, explaining6.51%of phenotypic variance and the substitution effect is59.58cm. These results confirmed previous reports.