Study On Gene Expression And Correlation Between Fat Deposition And Fat Metabolism In Duolang Sheep

In order to explore the relationship between intramuscular fat deposition and transcriptional activity of key enzyme genes in fat metabolism of Duolang sheep,48 Duolang sheep with a body weight of about18 kg were selected and fed in the same feeding conditions.The sheep were slaughtered when their body weight reached 20 kg,30 kg,40 kg and 50 kg.Ten Dorang sheep(5 RAMS and 5 ewe)with the closest body weight were selected for slaughter each time,and longissimus dorsi muscle samples were collected.In order to study the rule of fat deposition in muscle of 20～50 kg Duolang sheep,the fat content in samples was determined by Soxhlet extraction method,the meat quality and amino acid composition and content of samples were detected according to national standards,and the transcriptional activity of key enzyme genes in fat metabolism was determined by fluorescence quantitative PCR.The results showed that the muscle fat content of Duolang sheep increased with the increase of body weight,and the muscle fat content of Duolang sheep was the highest at the growth stage of 50 kg.The fat content at 40 kg stage was significantly different from that at 20 kg and 30 kg stages.Muscle shear force increased with increasing body weight,reaching a maximum at 50 kg and being significantly higher than at the other stages.The difference in muscle p H was not significant,but there was a decrease after 24 h.Ash content increased and moisture content decreased with increasing body weight.The content of various amino acids in Duolang mutton is complete.The contents of aspartic acid,leucine and lysine were higher,all above 6 mg/100 mg,and all were highest in 40 kg sheep at stage.The contents of flavor amino acids glutamic acid,cystine and methionine in 40 kg mutton were higher than those in other growth stages.The contents of essential amino acids,non-essential amino acids and flavor amino acids showed an increasing trend in 20～40 kg Duolang sheep,but the contents of three amino acids showed a decreasing trend in40～50 kg Duolang sheep,among which the total amount of amino acids had the largest fluctuation trend and the flavor amino acids had the smallest fluctuation trend.Fluorescence quantitative detection of the transcriptional activities of LPL,FASN,ACC,SCD,PKA,UCP1,PPARγ,EHHADH and HSL genes in longissimus dorsi muscle of Duolang sheep showed that the transcriptional activities of PKA and HSL genes in Duolang sheep reached the highest level at the 20 kg stage.Among them,PKA gene was significantly higher than that of other growth stages(P<0.05).The LPL,SCD and HSL genes in this stage were significantly higher than those in the 30 kg and 50 kg growth stages(P<0.05).The gene expression levels of LPL,FASN,ACC,SCD,UCP1,EHHADH and PPAR γ in 40 kg stage were the highest,which were significantly higher than those in other growth stages(P<0.05).The expression levels of FASN,ACC,UCP1 and EHHADH genes in 50 kg stage were significantly higher than those in 20 kg and 30 kg stages(P<0.05).In conclusion,the ability of adipocyte differentiation and lipolysis rate of Duolang sheep gradually decrease with the increase of body weight,while the rate of intramuscular fat synthesis gradually increases.The 40 kg stage is the most nutritious period and the most suitable slaughter period for Duolang sheep.