The Measurement Of Muacle Fiber Traits In A Large White Pig Population And The Association Analysis Of Candidate Genes Snp

Pork is the main source of meat products in China. With the improvement of people’s economics,people cared more on the meat quality rather than the amount ofdemandfor pork. The improvement of meat quality has now become important, but it is difficult for the genetic improvement. Muscle fibers make up themuscle, thecharacteristicsof muscle fibe directly affect the meatquality.The edible quality ofmusle (tenderness,flavor, juiciness) is closely relatedwith muscle fiber numbers, muscle fiberdiameter, muscle fiber area, muscle fiber types and intramuscular fat (IMF) content. By thestudy on muscle fibers properties in porcine populations,we can find genes related with meat quality, which can better guide us to domarker assisted breeding in practice.This study established anLarge White pigresource population, muscle fiber diameter, muscle fiber area were determined by HE staining. The polymorphism of Lpinl,BTG3to short diameter of muscle fiber, the long diameter, diameter and areawere analysed. By immunohistochemical method,the muscle fibre proportion of fast and slow muscle in11individuals were measured. By Real-Time PCR technology, the expression of slow muscle marker gene MYH7were detected. The results are as follows:(1) The muscle fiber traits for118Large White pigswere measured. The data showed that the short diameter of muscle fibers was51.26±8.46um, the long diameter was79.42±12.86um, the average diameter was67.30±10.76um, the average area was2976.14±973.31um2.The variation coefficients of short diameter,long diameter,average diameter and area of muscle fibers were17%,16%,16%and33%.(2) Phenotype correlation analysis between muscle fiber traits, carcass traits and meat quality traits were performed. The results showed that the partial correlation coefficient between area and diameter was0.5910, which wassignificant; the partial correlation coefficient between drip loss and pHl was0.3038, which was significant; the partial correlation coefficient between intramuscular fat and pHl was-0.1927, which was significant.(3) In the site93of exon2in Lpinl gene of pigs exists a C> T SNP, which is a synonymous mutation. Association analysis demonstrated that this SNP had no significant correlation with muscle fiber diameter and area.(4) In exon5of BTG3gene in pigs exists a C> T SNP, which caused an amino acid change. Association analysis revealed that this SNP had no significant correlation with muscle fiber diameterarea, but it had a significant correlation (p<0.01) with the following trait:the6-7thoracicbackfat, backfat located at thoracolumbar junction and pH1.Also this SNP had a significant correlation (p<0.01) withbackfat at the tenth rib.The intramuscular fat content of TT type was larger than CC type, and the difference was significant (P <0.05).(5) The proportion of fast and slow muscle fibers of longissimusdorsi of11pigs were detected through immunohistochemistry.Meanwhile, the expression levels of these tissues’ slow muscle marker gene MYH7were determined by absolute quantitative analysis. The results showed that there was a significant correlation between MYH7gene expression levels and the proportion of fast and slow muscle fibers.