Effects Of Selenium Supplementation On The Production Performance And Related Serum Biochemical Indexes Of Grazing Sheep

Object:In this paper,grazing sheep(pregnant ewes,lambs,growing ewes)were selected as research subjects at different physiological stages.Comprehensive evaluation of the effect of selenium supplementation on performance and serum indices of grazing sheep in Zhaosu pastoral area of Yili.(1)Effect of selenium supplementation on reproductive performance,serum Se,Cu,Zn content and antioxidant index of pregnant ewes.(2)Effects of selenium supplementation on growth performance,serum Se,Cu and Zn contents,antioxidant and immune indexes of lactating lambs.(3)Effects of selenium supplementation on growth performance,forage nutrient digestibility,serum Se,Cu,Zn content and antioxidant index of growing ewe.Method:Experiment one: Sixty Xinjiang fine-wool pregnant ewes,which were in good health and had similar age(3-4 years),similar body weight(53.51±2.87 kg),were randomly divided into two groups of 30 pregnant ewes in each group.The treatment group was treated with intramuscular injection of sodium selenite at 0.05 mg Se/kg 20 days before the mating ewes,while the control group was not treated.Blood samples were collected from pregnant ewes before injecting and in ewes at pregnant for 1 and 3 months,15 days before delivery and 15 days after delivery.3 pregnant ewes of 10 days before birth were slaughtered and their fetal tissues and organs(liver,kidney and muscle)were collected.Experiment two: Sixty Xinjiang fine-wool lactating lambs,which were in good health and had similar age(25.0±4.0 days),similar body weight(7.74±0.97 kg),were randomly divided into two groups of 30 lactating lambs in each group.The treatment group was treated with intramuscular injection of sodium selenite at 0.05 mg Se/kg,while the control group was not treated.Blood samples were taken,weighed and the number of weaned lambs was recorded from lactating lambs,when were collected twice before injecting and after 60 days.Experiment three: Forty Xinjiang fine-wool growing ewes,which were in good health and had similar age(7-8 months),similar body weight(36.43±1.90 kg),were randomly divided into two groups of 20 growing ewes in each group.The treatment group was treated with intramuscular injection of sodium selenite at 0.05 mg Se/kg,while the control group was not treated.Blood samples were collected from growing ewes before injecting and after 30 days.Result:Experiment one: The results showed that the serum selenium concentration of the pregnant ewes in the treatment group was significantly higher than that in the control group both in 1 and 3 months of pregnancy,15 days before delivery and 15 days postpartum(P<0.05);while serum concentration of Cu and Zn were identical in pregnant ewes of both groups at each time point(P>0.05).After selenium injection,comparing between time points,serum selenium,copper and zinc levels were not significantly different(P>0.05).Selenium supplementation improves the treatment group of pregnant ewes at different time points,which serum T-AOC,GSH-Px,T-SOD and Cu Zn-SOD activity(P<0.05).And serum MDA content was significantly decreased(P<0.05).After selenium injection,comparing between time points,serum T-AOC,GSH-Px,T-SOD,CuZn-SOD activity and MDA content were not significantly different(P>0.05).Selenium supplementation significantly improved the reproductive performance of ewes(P<0.05).Selenium supplementation significantly improves the selenium content in the liver,kidneys and muscles of pregnant ewes and fetuses(P<0.01);and liver GSH-Px activity is significantly increased(P<0.01).Experiment two: The results showed that the weaning survival rate was significantly higher in lactating lambs of treatment group than control group(P<0.05),while the weight of lambs was not increased at weaning(P>0.05).The serum concentration of Se was significantly higher in lactating lamb of treatment group than control group(P<0.01),while serum concentration of Cu and Zn were identical in lactating lamb of both groups(P>0.05).Selenium supplementation enhanced the serum T-AOC and GSH-Px activity(P<0.01),T-SOD and CuZn-SOD activity(P<0.05),and serum MDA content was significantly decreased(P<0.05)in lactating lamb.Selenium supplementation enhanced the serum T3content(P<0.05),serum T4 content and T4:T3 ratio were significantly decreased(P<0.05)in lactating lambs.Selenium supplementation were no significant difference in the content of TP and ALB(P>0.05),the contents of IgA,IgG,IgM and IL-2 were significantly increased(P<0.05)in lactating lambs.Experiment three: The results showed that the serum concentration of Se was significantly higher in growing ewes of treatment group than control group(P<0.01),while serum concentration of Cu and Zn were identical in growing ewes of both groups(P>0.05).Supplementing selenium significantly increased the average daily gain of growing ewes(P<0.05).Selenium supplementation enhanced the serum T-AOC and GSH-Px activity(P<0.01),T-SOD and CuZn-SOD activity(P<0.05),and serum MDA content was significantly decreased(P<0.01)in growing ewes.The apparent digestibility of nutrients and DMI were slightly increased in growing ewes,but the difference was not significant(P>0.05).Conclusion:The results indicated that selenium supplementation can significantly improve the production performance,serum selenium concentration,antioxidant enzymes and immune indexes of grazing sheep in Zhaosu pastoral area.But,there was no significant difference in feed intake,nutrient digestibility,copper and zinc concentrations of serum in grazing sheep.