Effects of Broussonetia papyrifera silage on the growth performance, blood parameters, immune function, and antioxidant capacity of Altay sheep

This study aimed to evaluate the effects of Broussonetia papyrifera silage on the growth performance, blood physiology, serum biochemistry, and immune and antioxidant functions of the serum and intestinal tissues of Altay sheep. Forty healthy male Altay sheep 5 months old, with an average weight of (30.12 ± 1.14) kg were randomly divided into two groups, each containing 20 sheep. Sheep in the control group were fed a basal diet, whereas those in the experimental group received a diet in which 20% of the forage had been replaced with B. papyrifera silage, whilst maintaining the same nutritional content. The study included a 10-day pre-trial period and a 60-day main trial, during which we measured growth performance; changes in blood physiology, serum biochemistry, and antioxidant markers in serum and intestinal tissues, levels of immunoglobulins and cytokine concentrations, were measured. The results revealed that there were no significant differences in the growth performance of sheep in the experimental and control groups. However, sheep in the experimental group were found to have significantly lower serum levels of neutrophils, lymphocytes, and eosinophils compared with those in the control group (P < 0.05). Furthermore, serum creatinine levels were significantly lower in the experimental group sheep (P < 0.05), whereas total antioxidant capacity, superoxide dismutase, catalase, and glutathione peroxidase activities in serum and intestinal tissues were significantly higher in these sheep, and the contents of malondialdehyde were significantly lower (P < 0.01). In addition, we detected significantly higher levels of immunoglobulin A, M, and G in both the serum and intestinal tissues of the experimental group sheep (P < 0.01), along with significantly higher levels of tumor necrosis factor-α and interleukins-2, -6, and -8, whereas the levels of interleukin-4 were significantly lower (P < 0.01). Collectively, these findings indicate that dietary supplementation with 20% B. papyrifera silage contributed to a significant enhancement of the immune function and antioxidant capacity of Altay sheep, in the absence of any evident detrimental effects on growth performance or blood parameters.