Abstract
This experiment aimed to study the effects of tannin supplementation on growth performance, rumen fermentation characteristics, apparent digestibility and serum biochemistry, and antioxidant and immune indexes in fattening lambs. A total of 36 male Hu sheep lambs (body weight = 15.83 ± 0.48 kg and days of age = 55 ± 2 d) were fed a high-concentrate diet and randomly divided into one of three groups of 12 animals each: control with no tannin (CON) and tannin treatments (TA1, 3 g/d per lamb; TA2, 6 g/d per lamb). The feeding experiment lasted for 60 d. The results showed that the average daily gain and ruminal propionate content of lambs in the TA1 group were higher (p < 0.05) than those in the CON group. Lambs fed tannin had significantly increased (p < 0.05) microbial protein and decreased (p < 0.05) ammonia nitrogen concentrations in the rumen. In addition, the crude protein and neutral detergent fiber digestibility of the TA2 group were significantly decreased (p < 0.05) as compared with the TA1 and CON groups, respectively. The serum concentrations of triglyceride, immunoglobulin A, and catalase and the total antioxidant capacity were higher (p < 0.05) in the TA1 group that those in the CON group, whereas an opposite trend of urea nitrogen, interleukin-1β, and malondialdehyde was found between the two groups. Also, tannin supplementation increased (p < 0.05) Lactobacillus and decreased (p < 0.05) Salmonella counts in the feces of lambs. Taken together, tannin supplementation can improve the growth performance, immunity, and antioxidant ability of fattening lambs fed a high-concentrate diet.