Study On The Developmental Expression Of The Genes Associated With Meat Quality In Chinese And Foreign Pig Breeds And The Association With Meat Quality Traits

Objectives1. To reveal the developmental expression of the candidate genes of CFL2b, MSTN, MyoD and MyoG for meat quality and the differences between chinese and foreign pig breeds.2. To reveal the variation of meat quality traits in the process of growth and chinese and foreign breed differences.3. To analysis the relationships between the expression of the candidate genes of CFL2, MSTN ,MyoD, MyoG with the meat quality ecoonomical traits and provide theoretical basis for early selection of the target traits in vivo .Methods1. 56 purebred sows were selected including 28 Hebao sows and Dabai sows. Each breed were divided into 2 groups and each group includes 7 points in time and each time point includes 4 pigs in each tine point under the same conditions were slaughted at the age of different days(3d, 30d, 60d, 90d, 120d, 150d and 180d)by routine method.Longissimus Muscle were preserved in liquid nitrogen for usage.2. Detect the meat quality traits:According to the second revision of the method of pork quality evaluation , the economic indicators of meat mainly including: pH value, intramuscular injection fat, shear value, muscle fiber diameter were revealed.The expression of the genes associated with meat quality traits and the economical meat quality traits were revealed by the method of Semi-quantitative RT-PCR.3. The expression tendencies of the candidate genes of CFL2b, MSTN, MyoD and MyoG for meat quality were revealed by Semi-quantitative RT-PCR.4. Statistic and analysis on the developmental expression tendencies and breed differences of the genes associated with pork quality and the genes associated with meat quality traits. Analysis relationships between the candidate genes for meat quality and the genes associated with meat quality traits.Results1. The variation of meat quality traits in the process of growth and chinese and exotic breed differences:the expression level of MyHCslow,MyHc2a mRNA were higher at the stage of 3d in both breeds,the expression level of MyHc2b mRNA were lower at the stage of 3d ,and then the genes of MyHCslow,MyHc2a mRNAdecreased significantly with day-old growth in both breeds(p<0.05),the gene of MyHc2b mRNA increased significantly with day-old growth in both breeds (p<0.05). Significant differences of both varieties were manifested after the stage of 30d. It shows that the expression of MyHCslow,MyHc2a mRNA in Hebao pigs is higher than it in Dabai pigs.The expression of MyHc2x mRNA decreased significantly During Early Growth Stage ,and than up-regulatedsignificantly (p <0.05) .the expression of MyHc2x mRNA in Dabai pigs is higher than it in Hebao pigs significantly(p <0.05). The variation of the meat quality ecoonomical traits in the process of growth and chinese and exotic breed differences:pH value decreased significantly with day-old growth in both breeds(p<0.05).2. The developmental expression tendencies of CFL2b,MSTN,MYOD,MYOG :The expression of CFL2b mRNA were lower at the stage of 3d in both varieties The gene of CFL2b up-regulated significantly during early growth Stage in both varieties (p<0.05),and then keep steady after 60d(Hebao pigs)/90d(Dabai pigs). Significant differences of varieties were manifested after the stage of 30d. It shows that the expression of CFL2b mRNA in Hebao pigs is lower than it in Dabai pigs (p<0.05). The developmental expression tendencies of the gene of MSTN, MyoD, MyoG are similar. The expression level of MSTN,MyoD,MyoG mRNA were lower at the stage of 3d in both varieties and then levels decreased significantly with day-old growth in both varieties (p<0.05). The expression level of MSTN in Hebao pigs is higher than it in Dabai pigs significantly (p<0.05) and the expression level of MyoD,MyoG in Hebao pigs is lower than it in Dabai pigs significantly (p<0.05). The value of muscle tender presents raised trend overall; The muscle fiber diameter in 3d is extremely fine to measure and then present rise trend with day-old growth . Intramuscular injection fat doesn′t change obviously. The pH value, intramuscular injection fat of Hebao pigs are higher than Dabai pigs significantly in each developmental stage; Hebao pigs′muscle fiber diameter is Significantly less than Dabai pigs′; Shear value in 3d and 120d is significantly lower than Dabai pigs′(p < 0.05), and the rest of day-old stage doesn′t present significant differences (p > 0.05).3. The relationship between the candidate genes for meat quality and the meat quality traits: the expression of CFL2b were significantly negative with MyHCslow, MyHC2a; positive with Myhc2b (p<0.05).There were no significant correlations between CFL2b and the genes associated with muscle fiber traits.Conclusions1 The expressions of MSTN, MyoG, MyoD, CFL2b showed regular developmental changes.The differences of the types appeard after the stageof 30d.2. The expressions of MyHCslow,MyHC2a,MyHC2b,MyHC2x ,PH value, intramuscular fat ,and the diametre of muscle fiber showed regular developmental changes.The meat quality of indigenous and exotic pig breeds differ significantly.The meat quality of Chinese pig breeds is far superior than exotic pig breed.3. High CFL2b expression level associated with poor meat quality .There were no significant association of MSTN, MyoG, MyoD with meat quality.