Abstract:

This experiment was conducted to study the effects of different nano-selenium levels on growth rate， blood biochemistry and antioxidant function and metabolome of Tan sheep. Sixty 3-month-old healthy fattening Tan sheep with the similar body weight were randomly assigned to four groups with 15 sheep in each， and three replicates of five sheep per group. As a control （CON） sheep in one group were fed a basal diet （selenium content 0.02 mg·kg^-1 DM， control group） while sheep in the other three ‘test’ groups （designated Ⅰ， Ⅱ and Ⅲ） were fed the basal diet with an additional 0.1， 0.3 and 0.5 mg·kg^-1 of nano-selenium， respectively. A pre-trial adjustment period lasted for 10 days and the experimental period lasted for 90 days. It was found that： 1） There were no significant group differences in growth rates of the Tan sheep （P > 0.05）. 2） The economic return from group Ⅰ （190.52 CNY） was higher than that in other groups （187.85， 174.92 and 131.01 CNY for Con， group Ⅱ and group Ⅲ， respectively）. 3） The contents of serum alanine aminotransferase （ALT） in test groups Ⅱ and Ⅲ were 13.75 and 13.25 U·L^-1 compared with 23.00 U·L^-1 in Con （P<0.05）， and an intermediate value of 18.50 U·L^-1 in Group Ⅲ； contents of urea were 8.26， 8.11， 7.52 mmol·L^-1， in groups Ⅰ， Ⅱ and Ⅲ， respectively； significantly lower than the CON group （10.19 mmol·L^-1） （P<0.05）. 4） The serum alkaline phosphatase （ALP） activity of Tan sheep in group Ⅲ （494.75 U·L^-1） was significantly higher than that in other groups （262.75， 228.00， 250.50 U·L^-1 for groups CON， Ⅰ and Ⅱ， respectively） （P<0.05）. 5） Group Ⅱ serum globulin （GLOB）， total antioxidant capacity （T-AOC） and glutathione peroxidase （GSH-Px） activity （42.48 g·L^-1， 9.91 U·mL^-1 and 183.93 U·mL^-1， respectively） were significantly higher than those of the CON group where corresponding values were 34.13 g·L^-1， 4.93 U·mL^-1 and 89.53 U·mL^-1 （P<0.05）. 6） A total of 21 metabolites with significant differences were screened through blood metabolomics analysis， with enrichment detected mainly in the metabolic pathways of pantothenate and CoA biosynthesis， carbohydrate digestion and absorption and vitamin digestion and absorption， among others. In summary， dietary supplementation with nano-selenium improved the body health and antioxidant capacity， which was shown to be related to the regulation of metabolic pathways in Tan sheep. In this experiment， the optimal amount of added dietary nano-selenium for Tan sheep was 0.3 mg·kg^-1.

Key words: selenium, Ningxia Tan sheep, blood serum, antioxidant, metabolome