Effects Of Different Dietary Energy Level On Slaughter Performance And The Expression Of HSL MRNA In Different Tissues Of Sheep

Choose healthy disease-free, 4 months old F2 generation of hybrids with similar weight crossbred ewes (Dorset sheep♂×Small Tail Han Sheep♀) ,which were randomly divided into 3 groups of 12,including group A (low-energy group), group B (middle-energy group),group C (high-energy group).As the control group,Group B was raised according to the energy requirement of American NRC(1985) Meet Sheep Feeding Standard, the energy level of metabolic energy group was 10.33 MJ / d, group A and group C based on middle-energy group on the reduction and increase of 30%,separately: that is, metabolizable energy of low energy level (group A) was 7.21 MJ / d, metabolizable energy of high energy level (group C) was 13.49 MJ / d, indicators of protein and other nutrients remained the same. After 50 days feeding, selected six sheep from each experimental group randomly and slaughtered, slaughter live weight,carcass weight,dressing percentage and backfat thickness were measured before slaughter, slaughter on both sides of longissimus muscle (12 ribs) and hind legs biceps femoris were obtained for intramuscular fat content. Longissimus, biceps femoris, heart and the subcutaneous adipose tissue samples were taken in the shortest time for extraction of total RNA. By optimizing the reaction conditions, using real time quantitative PCR method detected hormone-sensitive lipase (HSL) gene in longissimus, biceps femoris, heart and subcutaneous adipose tissue expression. The three energy levels effects on sheep HSL mRNA expression was analyzed. The results are as follows:1. Experimental sheep of the low-energy group before the slaughter live weight, carcass weight, dressing percentage of the low-energy group is significantly lower than that in the middle-energy group and the high-energy group (P<0.01 or P<0.05). The slaughter performance between the middle- energy group and the high-energy group was not significant difference (P>0.05); the sheep's back fat thickness, longissimus muscle and biceps femoris within the fat content of intramuscular fat content of the low-energy group was significantly lower than that in the middle-energy group and the high- energy group (P<0.01), the energy difference between the middle-energy group and the high-energy group were also significantly (P<0.01).The longissimus muscle shear force of high-energy group was significantly lower than the middle-energy group and the low energy group (P <0.01); The two head muscle shear force of the high-energy group was significantly lower than the low energy group (P <0.01).2. The expression of HSL mRNA decreased with the levels of dietary energy increased in longissimus muscle, biceps femoris, heart and subcutaneous adipose tissue;the absolute expression of HSL mRNA during the three groups in abdominal subcutaneous fat was significant difference (P<0.01), the expression in the low-energy group was significantly higher than the middle-energy group and the high-energy group expression; compared with the high-energy group, the expression in longissimus, biceps femoris of the low-energy group was significant difference (P<0.01), the energy difference between the middle-energy group and the high-energy group was significantly (P<0.05); the expression in the heart of the middle-energy group was significantly difference with the low-energy group and the high-energy group(P <0.05), and the low-energy group was significantly higher than the high-energy group (P <0.01).3. HSL gene in sheep adipose tissue, longissimus muscle, biceps femoris and heart tissue was expressed specificly, its expression in adipose tissue was highest and the lowest in the heart. The expression of in adipose tissue was significantly higher than in the longissimus muscle, biceps femoris, and heart (P<0.01).Besides, the expression of longissimus in muscle tissue was higher than in biceps femoris.