The Study On Pork Quality And Transcriptional Profiling Of Longissimus Dorsi Muscle On Beijing Black Pig

With the rapid development of economy and technology,people's living standards have been improved,and the concept have been changed from the number of pork to the quality of pork.The contradiction between declining pork quality and the consumer demand of high grade pork provided pork producers with a new direction.The quality of pork was mainly affected by inheritance,nutrition,slaughtering age and other environmental factors.In this study,the body weight,back fat,some meat quality traits and fatty acid components of Beijing black pig were analyzed to preliminary determine the suitable slaughter age of Beijing black pig.The differences of the body weight,back fat,some meat quality traits and fatty acid components of Beijing black pig fed with the diet of different energy levels were analyzed to determine the effects of energy level on the body weight,backfat,some meat quality traits and fatty acid components of Beijing black pig.Meanwhile,we completed transcriptome sequencing of longissimus muscle of Beijing black pig at 60 days,120 days and 180 days.Then function and enrichment analysis of differentially expressed genes were done to study the differences of the transcriptome level in the longissimus muscle,and to provide the molecular basis for the change of the related traits of Beijing black pig in different developmental stages.Body weight,backfat,part of the meat quality traits and fatty acid components of Beijing black pigs at 60,120,180,210,240,270 and 300 days were studied.The results showed that body weight,backfat,intramuscular fat and meat color(reddishness)increased,and the shear force decreased with the increase of age.The contents(mg/g)of total fatty acids,saturated fatty acids and monounsaturated fatty acids increased in general,and little change after 240 days,and the content of polyunsaturated fatty acids was stable with the increase of age.The percentage of saturated fatty acids and monounsaturated fatty acids increased,and the percentage of polyunsaturated fatty acids decreased with the increase of age.Therefore,with the increase of age,Beijing black pig meat quality can been improves by the increase of age.To mainly improve the intramuscular fat,meat color and fatty acid components,we determine that the suitable slaughter age of Beijing black pig is 240 days.Body weight,backfat,part of the meat quality traits and fatty acid components of Beijing black pigs fed by fed with the diet of different energy levels were studied.The results showed that Compared with the control group,the pH(24h)of the low energy group was significantly decreased,the drip loss and the meat color L were significantly increased,and the differences of other traits such as terminal body weight and intramuscular fat were not significant(P> 0.05).The back fat has a decreased trend,the shear force has increased trend(P> 0.05).The effect of energy level on the content and the percentage of fatty acids in the experiment was not significant.Thus,on the whole,low energy levels of diets cann't improvement the pork quality of Beijing black.Transcriptome sequencing of longissimus muscle of Beijing black pig at 60 days,120 days and 180 days and bioinformatics analysis were completed.The results showed that compared with 120 days,there were 1569 differentially expressed genes,682 down-regulated genes and 887 up-regulated genes at 60 days,and compared with 180 days,there were 2997 differentially expressed genes,1350 down-regulated genes and 1647 up-regulated genes at 60 days,and 844 down-regulated genes,1064 up-regulated genes at 120 days.Differentially expressed genes are involved in a variety of biological processes and executive different biological functions.These differentially expressed genes are involved in not only immune pathways but also many pathways related to fat traits,such as AMPK signaling pathways,fatty acid metabolism,insulin signaling pathway,FoxO signaling pathway and PPAR signaling pathway,etc.