Gastrointestinal Microflora And The Growth And Biochemical Criteria Analyses Of The Myostatin Gene Edited Beef Cattle

Myostatin(MSTN)is a negative regulator of skeletal muscle mass.It can inhibit the formation and differentiation of muscle cells.The mutation or deletion of its nucleotides could impair the protein functions and result in the proliferation and hypertrophy of muscle cells.Gastrointestinal microflora play key roles in the digestion and metabolism of ruminant animals and can affect their blood biochemistry as well.Thus,they are closely related to the growth and development of the host.To evaluate whether the composition of the gastrointestinal microflora would be affected in the rumen of MSTN gene editing beef cattle,6 MSTN gene editing cattle(MSTN group)and 6 normal cattle(control group)were used in the current study.Their gastrointestinal microflora compositions,growth traits,blood biochemical indicators were measured and compared monthly,starting from 1 month to 12 months of age.The results were as follows.(1)The body weight,body length,body height and cross section of MSTN group at 1,3,6 and 12 months of age were significantly or extremely significantly higher than control group.(2)Among the blood biochemical indicators,the serum alkaline phosphatase level in MSTN group at 3 and 6 months of age was significantly higher than that in control group(P<0.05).The blood glucose level in control group at 1,3 and 6 months of age was significantly higher than that in MSTN group(P<0.05).The blood urea nitrogen content in heifers at 1 and 6 months of age and in bull calves at 6 months of age in MSTN group was significantly lower than that in the control group(P<0.05).The serum creatinine level in MSTN group at 3 months of age was significantly higher than that in control group(P<0.05).The serum globulin content of heifers and bull calves in MSTN group at 1 month of age was extremely significantly higher(P<0.01)and significantly higher(P<0.05)than that in control group,respectively.These results indicate that MSTN gene editing cattle may have higher blood glucose decomposition capability and protein catabolism level than control group,as well as the immunity at 1 month of age.(3)The composition of gastrointestinal microflora and cluster analysis showed that the distribution of microflora of MSTN and control group was different,and not affected by the gender.The difference of microflora between MSTN and control group at 1 month of age of was significant,while the distribution of microflora in the cows was similar,indicating that the effect of cow-calf influence was not significant.With the increase of the age,the composition of the microflora was significantly increased.Lactobacillus johnsonii,Oscillibacter valericigenes and Lactobacillus reuteri were the dominant bacteria of the calves,and the abundance of these beneficial bacteria was higher in MSTN group than in control group.Two other probiotic functional bacteria,Bifidobacterium bifidum and Butyricicoccus pullicaecorum,were the specific bacteria of the MSTN group at 1 month of age.Eubacterium callanderi and Bacteroides coprophilus were the dominant bacteria of these calves at 6 and 12 months of age.The band of the MSTN group at 3,6 and 12 months of age was identified as Oscillibacter ruminantium.In conclusion,MSTN gene editing influences the composition of part of digestive tract microflora.Its correlation with blood biochemical indexes and growth traits,as well as the mechanism and pathways,need further investigation.