Comparative Analysis Of Meat Quality Characteristics,Muscle Transcriptome And Cecal Microorganisms Composition Of New Zealand White Rabbit And Yufeng Yellow Rabbit

Rabbit meat is a kind of meat with high protein,low fat and low cholesterol.It contains eight essential amino acids that can’t be synthesized by the human body.Moreover,it is easy to digest and absorb after processing and is not easy to get fat after eating.It is also a healthy meat product to strengthen the body.Therefore,rabbit meat is deeply loved by the majority of consumers.However,The contents of fat and cholesterol in rabbit meat is lower than that of other meat,so the taste of rabbit meat is rough,which makes it difficult to promote rabbit meat and its products.Meat production performance is an important economic shape of rabbits.Improving the quality of rabbit meat can promote the further development of rabbit meat industry.To solve this problem,the performance indexes of meat quality of 70 d New Zealand white rabbits and 70 d Yufeng yellow rabbits were measured and analyzed.RNA-seq and mi RNA-seq were performed on longissimus dorsi muscle tissue to compare the differentially expressed m RNA and mi RNA in longissimus dorsi muscle of different breeds rabbits.The key mi RNAs and their target genes affecting intramuscular fat deposition and metabolism were selected.In addition,16 S r DNA sequencing was performed on the cecal contents of 70 d New Zealand white rabbits and 70 d Yufeng yellow rabbits to select the key microbial communities affecting the meat quality of rabbits.The purpose is to provide a theoretical basis for the identification of genes related to rabbit meat quality and the study of microbiome.The main results are as follows:（1）The results of meat quality indexes showed that the drip loss of longissimus dorsi muscle of Yufeng yellow rabbits was significantly lower than that of New Zealand white rabbits（P < 0.05）,the cooking loss and shear force were lower than that of New Zealand white rabbits（P > 0.05）.The content of IMF of Yufeng yellow rabbits was significantly higher than that of New Zealand white rabbits（P < 0.01）.The p H values of longissimus dorsi muscle of the two breeds were in the normal range.The content of DHA（C22:6 n3）in the longissimus dorsi muscle of Yufeng yellow rabbits was significantly higher than that of New Zealand white rabbits（P < 0.05）,the content of ginkgolic acid（C15:0）was significantly lower than that of New Zealand white rabbits（P < 0.05）,the content of palmitic acid（C16:0）and eicosatrienoic acid（C20:3 n3）was significantly higher than that of New Zealand white rabbits（P < 0.01）,and the content of n-3 PUFA was significantly higher than that of New Zealand white rabbits（P < 0.05）,The contents of delicious amino acids were higher than that of New Zealand white rabbits（P > 0.05）.（2）The m RNA and mi RNA libraries of longissimus dorsi muscle of Yufeng yellow rabbits and New Zealand white rabbits were successfully constructed.A total of 1175 differentially expressed genes were identified in the longissimus dorsi muscle of two breeds rabbits.There were 340 differentially expressed genes were up-regulated and 835 differentially expressed genes were down-regulated in New Zealand white rabbits.A total of 138 differentially expressed mi RNAs were identified in the longissimus dorsi muscle of two breeds rabbits,of which 31 mi RNAs were up-regulated and 107 mi RNAs were down regulated in New Zealand white rabbits.The enrichment results of GO and KEGG showed that the DEGs and the target genes of DEmi RNAs were enriched in the GO items such as lipid binding,long-chain fatty acid binding,lipid metabolism and fatty acid metabolism.It also enriched in PPAR signaling pathway,glycerol phospholipid metabolism and other pathways which related to lipid deposition.Candidate target gene pairs related to lipid deposition and metabolism such as mi R-973-y-GPX7,ocu-mi R-124-3p-GPD2,ocu-mi R-2355-5p-BDH1 and ocu-mi R-301b-3p-ACER2 were identified.The correlation analysis between DEGs and IMF showed that the contents of IMF were positively correlated with PAFAH2（P < 0.01）and HSD11B2（P < 0.05）,but negatively correlated with PRKAG2（P < 0.01）.（3）High-throughput sequencing of 16 S r RNA V3-V4 region of cecal contents of 70 days of New Zealand white rabbits and 70 days of Yufeng yellow rabbits showed that the diversity and richness of cecal contents flora of Yufeng yellow rabbits were higher than that of New Zealand white rabbits.Firmicutes and Bacteroidetes were the dominant bacteria in the cecal microorganisms of the two breeds rabbits,and Akkermansia was the dominant bacteria.At the phylum level,the abundance of Euryarchaeota and Tenericutes in the cecal contents flora of New Zealand white rabbits was significantly higher than that of Yufeng yellow rabbits（P < 0.05）.At the genus level,compared with Yufeng yellow rabbits,the abundance of Ruminiclostridium₆ and Phascolarctobacterium in the cecal contents of New Zealand white rabbits decreased significantly（P < 0.05）,the abundance of Methanobrevibacter increased significantly（P < 0.05）.Tax4 fun analysis showed that the cecal microorganisms of New Zealand white rabbits and Yufeng yellow rabbits were mainly involved in carbohydrate metabolism,amino acid metabolism and energy metabolism.The results of correlation analysis showed that there was a significant positive correlation between Ruminiclostridium₆ and intramuscular fat content（P < 0.05）.Phascolarctobacterium was negatively correlated with C15:0（P < 0.01）and positively correlated with drip loss and C20:3 n3（P < 0.05）.There was a very significant negative correlation between Methanobrevibacter and intramuscular fat content（P < 0.01）.On the basis of comparing the phenotypes of muscle quality differences of different breeds of rabbits,this study identified the pathways,candidate target gene pairs and microbial communities related to intramuscular fat deposition and metabolism through transcriptome and 16 S r DNA sequencing.The results provide reference for further analysis of the regulatory mechanism of rabbit meat quality characteristics and improvement of rabbit meat quality.It also lays a foundation for genetic improvement and molecular breeding of rabbit meat performance.It has very important practical significance for rabbit breeding industry.