饲粮能量水平对白萨福克×湖羊F1羔羊生产性能和脂肪代谢相关基因表达的影响

Effects of Dietary Energy Levels on Performance and mRNA Expression of Fat Metabolism-related Genes in White Suffolk×Hu F1 Lambs

该试验旨在研究饲粮能量水平对萨湖F1代羔羊生产性能、血清生化指标及脂肪相关基因表达的影响。选取2月龄左右、健康、体重为20.45±1.52 kg白萨福克×湖羊F1代羔羊36只,随机分3个处理组(每组4个重复,每个重复3只羊)分别饲喂消化能为8.67 MJ/kg(LE)、10.38 MJ/kg(CON)和12.31 MJ/kg(HE),蛋白水平均为14.36%的试验饲粮,预试期8 d,正试期70 d。试验期间测定羔羊生长性能,饲养试验结束后所有羊颈静脉采血,并于每个重复随机选取1只羔羊屠宰,测定屠宰性能和肉质性状、血清生化指标及脂肪相关基因的表达。结果表明,低饲粮能量水平(8.67 MJ/kg)可显著降低羔羊的末重、平均日增重和宰前活重,并显著升高料肉比(P<0.05);随着饲粮能量水平的升高,HE组的血清总胆固醇、低密度脂蛋白、高密度脂蛋白和总蛋白水平显著高于CON组和LE组(P<0.05)。HE组的甘油三酯水平显著高于CON组和LE组(P<0.05);饲粮能量水平增加会显著提高皮下脂中ACC、HSL,尾脂中ACC、FASN和背最长肌中FABP4基因mRNA的表达量(P<0.05),显著降低尾脂中HSL和背最长肌中ACC、PPARγ、HSL基因mRNA的表达量(P<0.05)。饲粮能量水平过高或过低均会抑制皮下脂和尾脂的FABP4与背最长肌中FASN mRNA的表达,CON组表达水平最高(P<0.05)。综合生产性能、血清生化指标和脂肪代谢基因的表达得出,饲粮消化能水平为12.31 MJ/kg时更适用于2~4月龄白萨湖F1代羔羊的生长发育和体脂沉积。

The experiment aimed to study the effects of dietary energy levels on the performance,serum biochemical index and mRNA expression of fat-related genes in white Suffolk×Hu F1 lambs.Thirty-six healthy F1 generation lambs of white Suffolk×Hu sheep with similar body weight were selected and randomly divided into 3 groups(4 replicates in each group and 3 sheep in each replicate).The digestive energy of diet was 8.67 MJ/kg(LE),10.38 MJ/kg(CON)and 12.31 MJ/kg(HE)in each group respectively,and the crude protein level averaged 14.36%.The pre-test period was 8 days,and the trial period was 70 days.Growth performance of lambs were measured during the experiment.On the last day of experiment,blood was collected from the jugular vein of all tested sheep,and one lamb was randomly selected for slaughter in each group to detect production performance,serum biochemical indicators and fat-related genes expression.The results showed that the low energy levels(8.67 MJ/kg)significantly reduced the lamb's final weight,average daily gain and live weight before slaughter,and increased the feed-to-meat ratio(P<0.05).With the rise of energy level,serum total cholesterol,low-density lipoprotein,high-density lipoprotein,and total protein of the HE group were significantly higher than those of the CON and LE groups(P<0.05).The level of triglycerides in the HE group was significantly higher than those in the CON and LE groups(P<0.05).The increase of dietary energy levels significantly increased(P<0.05)the mRNA expression of fat deposition-related genes in subcutaneous fat(ACC,HSL),tail fat(ACC,FASN)and longissimus dorsi(FABP4)and significantly reduced(P<0.05)the mRNA expression of fat metabolism-related genes in tail fat(HSL)and longissimus dorsi(ACC,PPARγ,HSL).Either higher or lower energy level in the diet can inhibit the mRNA expression of FABP4 in subcutaneous fat and tail fat,and of FASN in longissimus dorsi muscle,with CON group having the highest expression(P<0.05).The expression of productive performance,serum biochemical indicators and fat metabolism genes revealed that the more suitable digestive energy level for the development and fat deposition of 2 to 4 months old white Suffolk×Hu F1 lambs is 12.31 MJ/kg.