Enzyme-Treated Soybean Meal Enhanced Performance via Improving Immune Response, Intestinal Morphology and Barrier Function of Nursery Pigs in Antibiotic Free Diets

This study aims to investigate the effects of ESBM on performance, antioxidant status, immune response, and intestinal barrier function of nursery pigs in antibiotic free diets compared with EFS. A total of 32 Duroc × (Landrace × Yorkshire) barrows (initial body weight of 8.05 ± 0.66 kg, weaned on d 28) were selected and allocated to two treatments with 16 replicates per treatment and one pig per replicate using a complete random design. The treatments included an EFS group (basal diet + 24% EFS; EFS) and an ESBM group (basal diet + 15% ESBM; ESBM). Corn was used to balance energy and diets were iso-nitrogenous at about 18% crude protein. The experiment lasted for 14 days and pigs were slaughtered for sampling on d 14. Compared with EFS, pigs fed ESBM showed enhanced (p < 0.05) gain to feed ratio and average daily gain and a reduced (p < 0.05) diarrhea score. These pigs had increased (p < 0.05) contents of glutathione peroxidase, catalase, superoxide dismutase, IgG, interleukin-10, and ferric reducing ability of plasma, as well as decreased (p < 0.05) malondialdehyde, IL-6, IL-1β, tumor necrosis factor (TNF-α), interferon-γ, thiobarbituric acid-reactive substances, and diamine oxidase level in serum and TNF-α level in the jejunal mucosa. Moreover, these pigs also showed enhanced (p < 0.05) villus height/crypt depth in ileum, villus height in duodenum, protein expression of zonula-occludens-1 in jejunal mucosa, and fecal total volatile fatty acids and butyric acid contents. In conclusion, ESBM replacing EFS could enhance performance via improving immune response, antioxidant status, gut morphology, and barrier function of nursery pigs in antibiotic free diets.