Combination Effects of Clostridium butyricum and Glucose Oxidase on Intestinal Antioxidant Status, Immune Responses, Barrier-Related Gene Expression, and Cecal Short-Chain Fatty Acid Profiles in Broilers.

The potential of combining Clostridium butyricum (CB) and glucose oxidase (GOD) in poultry production remains to be systematically evaluated. This study evaluated the effects of dietary CB and GOD, supplied alone or in combination, on ileal antioxidant status, jejunal immune responses, gut epithelial barrier function, and cecal short-chain fatty acid (SCFA) composition in broilers, with the aim of comparing their practical effects rather than investigating synergistic or interactive effects. A total of 192 1-day-old broilers (white-feathered) were randomly distributed among 4 experimental groups, each having 6 replicate pens of 8 chicks. The groups had comparable starting weights (43.53 ± 0.51 g) and an equal male-to-female ratio. The control diet (CON) contained no additives, whereas the other three diets were formulated with CB at an inclusion rate of 400 mg/kg, GOD at the same level, or a mixture of both (400 mg/kg each), corresponding to the CB, GOD, and MIX groups, respectively. This experiment spanned 42 days, comprising an early stage (from day 1 to day 21) and a later stage (from day 22 to day 42). At day 21, the GOD group exhibited a significant elevation in ileal SOD activity relative to the CON group (p < 0.05). Jejunal interleukin-6 (IL-6) levels were significantly decreased in the CB and MIX groups (p < 0.05), while the MIX group also showed a significant decrease in IL-2 and a significant increase in interleukin-10 (IL-10) levels (p < 0.05). The GOD and MIX groups showed a significant elevation of sIgA (p < 0.05), while the CB and GOD groups exhibited marked upregulation of Occludin mRNA (p < 0.05). Butyrate concentrations in the cecum were significantly higher in the CB group than in the CON group (p < 0.05). Likewise, acetate levels were elevated in the MIX group compared with CON (p < 0.05). At day 42, the MIX group exhibited a significant reduction in ileal MDA content compared with the control (p < 0.05). In the jejunum of the MIX group, IL-6 was significantly reduced and IL-10 was significantly elevated (p < 0.05). Additionally, ZO-1 mRNA expression was markedly upregulated in the same group (p < 0.05). Ileal GSH-Px activity was significantly higher only in the CB group (p < 0.05). Overall, combined supplementation with CB and GOD exerted beneficial effects on broiler antioxidant status, immune responses, intestinal barrier-related parameters, and cecal SCFA composition, although the magnitude of these effects varied among endpoints and sampling ages.