Effects Of Diet With Different Zinc And Manganese Levels On Growth Performance And SOD MRNA Expression In The Liver Of Jirong Rabbits

Zinc and manganese play an important role in the progress of animal growth and development.In order to meet the animal growth needs,exogenous zinc and manganese were added to animal feed.The experiment was conducted to study the effect of the diffrent dietary zinc and manganese levels on growth performance,digestive performance,serum biochemical indexes and liver SOD expression of Jirong rabbits.Then we can judge the proper amount of diet zinc and manganese of Jirong rabbits.Ninety healthy Jirong rabbits(60 day-age)with similar weight were randomly divided into 10 groups with three replicates.The experiment was studied by 3×3 complete random design.Different levels of zinc(30,60,and 90 mg/kg)and manganese(5,10 and 15 mg/kg)were added in the diet,and the control group was fed with the basal diet.The growth and slaughter performance indicators of Jirong rabbits were measured.Serum biochemical indexes and superoxide dismutase activity were determinated.Digestion trial on Jirong rabbits was carried out by means of collection full excrements analysis method.Dietary nutrient digestion and trace elements deposition were investigated.And the expression levels of liver SOD were determined.The results showed that,average daily gain in the first 30 days was significantly affected by dietary Mn levels(P<0.05).Average daily gain in the last 40 days was significantly affected by dietary Zn levels(P<0.05).There were no significant difference in final body weight,average daily gain and feed/gain ratio(P>0.05),instead there were significant interactions between Zn and Mn levels(P<0.05).There were no significant difference in slaughter performance,but the carcass weight,dressing percentage and the skin areawere were higher in most trial groups than those in the control group.The activity of serum metabolic enzymes and the content of the product of protein metabolism were not significantly affected(P>0.05),and there were no significant interactions between Zn and Mn levels(P>0.05).But the content of total protein,albumin and globulin in serum were higher in trial groups than that in the control group.The activity of serum ALT was higher than that in control group with different dietary Mn levels(P<0.05).The dietary Zn levels significantly increased serum Cu Zn-SOD activity with Mn-SOD activity significantly dicreased(P<0.01).Serum Mn-SOD activity was significantly affected by dietary Mn levels(P<0.05)and there were significant interactions between Zn and Mn levels(P<0.05).There were no significant influence in serum Cu Zn-SOD activity at different Mn levels(P>0.05).The crude fat digestibility was significantly affected by diet Zn and Mn levels(P<0.01),but there were no significant influence in CP and CF digestibility(P>0.05).Dry matter digestibility was significantly affected by dietary Zn levels(P<0.05).There were significant interactions between Zn and Mn levels(P<0.01)in most digestion indexs.Zn,Mn and Cu deposition in feces was significantly affected by dietary Zn levels(P<0.05).There were no significant influences in Zn,Mn,Cu and Fe deposition in feces with different dietary Mn levels and there were no significant interactions between Zn and Mn levels(P>0.05).The expression levels of SOD 1 and SOD 2 gene in liver were not significantly affected by dietary Zn levels(P>0.05).The expression levels of SOD 1 was significantly affected by dietary Mn levels(P<0.05),and the expression levels of SOD 2 was extremely significant affected(P<0.01).The expression levels of SOD 1 and SOD 2 gene in liver were highest when there are 60 mg/kg Zn and 15 mg/kg Mn in feed,and significant difference was found in the other groups(P<0.05).In conclusion,diet zinc and manganese can effectively improve the production performance and liver SOD gene expression of Ji Rong rabbits.The recommended adding amounts of zinc and manganese are 60 mg/kg and 15 mg/kg.