Study On The Difference Of Rumen Microflora Structure And Expression Level Related On Growth And Meat Quality Between Smalltailed Han And Dorper×Small-tailed Han Sheep

China is the world’s largest producer and consumer of sheep meat,but the slow growth rate and long production cycle of local domestic mutton sheep breeds cannot meet consumer demand,so large quantities of sheep meat need to be imported from abroad each year.Small-tailed han,a local Chinese breed known for its excellent breeding performance,is widely reared in northern China,but it produces little meat and grows slowly.With the introduction of the Dorper and other commercial meat sheep,especially the Dorper×Small-Tailed han sheep,this problem has been well improved.The Dorper×Small-tailed han sheep is a new group of sheep bred from a cross between the African introduced Dorper sheep as a sire and the local Small-tailed han.A number of comparisons have been made between Dorper × Small-tailed han and other sheep in terms of production and it has been found that Dorper × Small-tailed han is superior in terms of growth and development and meat production in the same environment.However,there are no detailed reports on the differences between Dorper × Small-tailed Han and Small-tailed han in terms of growth and development,meat quality traits and rumen flora,so this trial was carried out to compare Smalltailed han with Dorper × Small-tailed han sheep in various aspects.The results of this study can be used as a reference for production practice.In this study,6-month-old Small-tailed han sheep and Dorper ×Small-tailed han sheep the weight,and slaughter performance and meat quality traits were measured to assess phenotypic differences between the two groups of sheep.Transcriptome sequencing was performed to analyse differentially expressed genes within liver and Longissimus dorsi.Ruminal fluid was sequenced for16 S r RNA to identify differences in rumen flora.The results of the study showed that the average daily gain,carcass weight and carcass rate were significantly lower in small-tailed han sheep than in Dorper ×Small-tailed han.In terms of meat quality,there were significant differences（P < 0.05）in cooked meat rate,24-hour meat colour（b value）,1-hour p H and shear force between the two groups of sheep.In the liver and muscle transcriptome analysis,358 and 723 differentially expressed genes were obtained,respectively.Among these genes,such as TGFB1,FABP3,FABP4,and PLIN2 may be associated with weight gain in Dorper ×Small-tailed han sheep.In rumen flora differential analysis,Dorper ×Small-tailed han sheep had higher rumen flora diversity and more bacteria were measured.The abundance of Bacteroidetes phylum was significantly higher in Dorper ×Small-tailed han sheep than in Small-tailed han（P = 0.01）,which may be related to the early maturation trait of Dorper ×Small-tailed han sheep;several bacteria that differed at the taxonomic level of the genus,such as Ruminococcus＿1,Ruminobacter,play an important role in the degradation of ruminal cellulose.