| Due to the lack of specialized mutton sheep breeds with fast growth,good reproductive performance and good meat quality in China,the supply of high-quality mutton exceeds the demand.The Suffolk×Hu F1 generation sheep has excellent fattening,slaughter performance and good meat quality,but there are few studies on its meat nutrition and body fat deposition in early nutrition.The study used early nutritional levels to determine the performance,blood indicators,fatty acid composition and fat metabolism genes expression of Suffolk×Hu F1 generation lambs at the age of 2-4 months,in order to explore the effects of early nutrition on the production,meat nutrition,the pattern of body fat deposition and provides a reference basis for the use of this hybrid breed.In this study,60 F1 lambs were randomly divided into 5 treatments with 4 repeats per treatment and 3 lambs per repetition.The experiment was divided into standard group(10.38MJ/kg,14.36%),low-energy group(8.67 MJ/kg,14.36%),low-protein group(10.30MJ/kg,11.48%),high-energy group(12.31 MJ/kg,14.40%)and high-protein group(10.30MJ/kg,17.25%).At the end of the feeding experiment,adipose tissue(subcutaneous fat,tail fat and perirenal fat)and longissimus dorsi were collected to determine the composition of fatty acids and the expression of fat-related genes after be slaughtered.1.The effect of dietary nutrition level on production performance and blood biochemical indicatorsLow-nutrient diets significantly reduced the lamb’s final weight,average daily gain and live weight before slaughter(P<0.05),and high-nutrient diets significantly reduced the feed-to-meat ratio of lambs(P<0.05).The effect of dietary energy level on lamb slaughter performance was better than that of protein level;High-energy diet significantly promoted the body’s lipid and protein metabolism(P<0.05),high-protein diet promoted the body’s protein metabolism.2.The effect of dietary nutrition level on fatty acid composition and fat metabolism genes expression of longissimus dorsi muscleWith the increase of energy levels,C22:2,C20:5n3,C22:6n3,PUFA and P/S increased significantly(P<0.05),while SFA,MUFA,C18:3n6 and C18:1n9 decreased significantly(P<0.05).As the protein levels increased,C18:0,C24:0 and C20:5n3 increased significantly(P<0.05).The dietary energy levels had a positive effect on the IMF content of longissimus dorsi muscle,but the high-protein diet had a tendency to decrease.Low-nutrition diets could significantly increase the expression of gene HSL mRNA(P<0.05).The expression of gene PPARγ significantly decreased(P<0.05),the expression of FABP4 was oposite(P<0.05).The high protein group significantly reduced the expression of genes PPARγ and LPL(P<0.05).3.The effect of dietary nutrition level on the expression of fat metabolism genes in different adipose tissuesWith the increase of dietary energy level,the expression of subcutaneous fat(ACC,HSL)and tail fat(FASN,ACC,LPL)fat deposition genes gradually increased,and the expression of HSL and LPL genes increased significantly(P<0.05),while the HSL in the tail fat was significantly reduced.Low-energy diet significantly increased the expression of FASN,FABP4,LPL and HSL genes in perirenal fat(P<0.05);Low-protein diets significantly increased subcutaneous fat(PPARγ,FABP4),perirenal fat(FASN)and adipose tissue(LPL and HSL)gene expression(P<0.05),but significantly reduced the gene expression of subcutaneous fat(FASN)and tail fat(FASN,ACC,PPARγ,FABP4)(P<0.05).High-protein diet significantly reduced the gene expression of perirenal fat(PPARγ,FABP4)(P<0.05),but significantly increased the expression of subcutaneous fat ACC gene(P<0.05).In summary,Suffolk×Hu F1 lambs fed with high-energy diet(12.31 MJ/kg,14.40%)and high-protein diet(10.30 MJ/kg,17.25%)at the age of 2-4 months could improve their production performance,serum biochemical indicators,fatty acid composition of the longissimus dorsi.Among them,high-energy diet had a better effect on promoting the expression of body fat genes and the deposition of IMF in the longissimus dorsi. |
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