Supplementation of curcumin promotes the intestinal structure, immune barrier function and cecal microbiota composition of laying hens in early laying period

The prelaying period is critical for laying hens, marked by significant physiological changes such as increased egg production, hormone secretion, and higher nutritional demands. These changes stress the intestine, which is vital for nutrient digestion, absorption, immune defense, and maintaining antioxidant and microbial balance. During this period, maintaining the intestinal health is essential for efficient nutrient absorption. Curcumin, a plant-derived extract, offers antioxidant, anti-inflammatory, antimicrobial, and immunomodulatory benefits, that can improve gut function. This study evaluated the effects of curcumin on the intestinal structure, immune barrier function, and cecal microbiota composition in laying hens during their early laying period. A total of 180 Snowy White chickens (154 days old) were divided into 5 experimental groups, receiving curcumin at 0 mg/kg, 100 mg/kg, 200 mg/kg, 300 mg/kg, and 400 mg/kg for 12 wk. The results showed that curcumin significantly improved the intestinal morphology (P < 0.05), increased mRNA expression of digestive enzymes (such as MGAM, SI, and ANPEP), and enhanced the digestive and absorptive functions. Further, curcumin improved the levels of antioxidant parameters (such as CAT, GSH-PX, T-AOC, and T-SOD) in the ileum, jejunum, and duodenum, and increased the expression of immunoglobulins (IgA, IgM, IgG) in the intestinal segments and serum (P < 0.05). Curcumin also improved the intestinal immune barrier function by increasing ZO-1 and Occludin expression. Furthermore, it altered the gut microbiota composition by increasing the relative abundance of beneficial bacterial phyla such as Bacteroidetes, Actinobacteria, Proteobacteria, and Fusobacteria (P < 0.05). At the genus level, curcumin supplementation enhanced the beneficial genera like Phocaeicola, Alistipes, Prevotella, Barnesiella, and Bifidobacterium (P < 0.05), thereby promoting the gut health and microbial diversity. In conclusion, curcumin supplementation during the early laying period of hens offers significant benefits by improving the intestinal health, immune function, and gut microbiota composition. Hence, curcumin serves as a promising dietary additive to support nutrient absorption and immune defense in laying hens during the early laying period of hens.