Effect of Vitamin C and Probiotics on Broilers Performance and Claudin-2 (CLDN-2) Expression Under Heat Stress

This study was conducted to investigate the effect of vitamin C and probiotic which consists of five species of beneficial bacteria and two species of fungi on performance, blood parameters, and intestinal CLDN-2 gene expression of broilers during heat stress (HS). A total of 400 broilers were randomly divided into five groups, each of which received a different treatment. The first group was considered a negative control and did not experience any HS (C-); the second group was considered a positive control (C+) and was exposed to HS; the third group received only vitamin C (250 mg/L in drinking water); the fourth group received only the recommended dose of probiotics; and the fifth group received a combination of both vitamin C and probiotics (250 mg/L in drinking water and recommended dose, respectively). The broiler's performance, blood parameters, and intestinal CLDN-2 gene expression were assessed. The results showed that the administration of probiotics and vitamin C increased the broiler's feed intake and decreased the feed conversion ratio (p < 0.05). Heat stress increased the broiler's blood total protein, glucose, cholesterol, triglyceride, and liver enzyme concentration (p < 0.05). While the supplementation of vitamin C and probiotics decreased these parameters during HS (p < 0.05). Vitamin C administration reduced the intestinal CLDN-2 gene expression in broilers, during HS (p < 0.05). Heat stress negatively affected the broiler's performance and increased the mortality rate and intestinal CLDN-2 gene expression, whereas, the supplementation of vitamin C decreased the deleterious effect of HS in broilers.