Dietary supplementation of dried plum:a novel strategy to mitigate heat stress in broiler chickens

Background:Heat stress is a significant problem in the poultry industry, causing a severe economic loss due to its detrimental effects on chickens' health and performance. Dried plum (DP) is a good source of minerals, vitamins, antioxidants, and phenolic compounds. Studies have suggested that DP has several health benefits, such as maintaining the body's redox system, immune status, and calcium hemostasis. Based on the health benefits of DP, we hypothesized that the dietary supplementation of DP would alleviate the detrimental effects of heat stress on broiler chickens. Results:To test the hypothesis, day-old broiler chicks (n=72) were randomly allocated to three treatment groups (n=24/group):no heat stress (NHS), heat stress (HS), and heat stress with dried plum (HS+DP), and reared under standard conditions. The inclusion of 2.5％DP in the feed of the HS+DP group was made during the treatment period, while birds in other groups were provided with a standard finisher diet. After 21 days, birds in the HS and HS+DP groups were exposed to cyclic heat stress conditions (33 ℃ for 8 h during daytime) for 3 weeks, while those in the NHS group were reared under normal conditions (22–24 ℃). Weekly body weight and feed intake were recorded to calculate the average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). Heat stress significantly decreased the final body weight, ADG, ADFI, and increased FCR compared to the NHS group, whereas dietary supplementation of DP significantly improved these growth performance parameters compared to the HS group. Furthermore, supplementation of DP significantly increased the expression of heat shock protein-related genes (HSF1, HSF3, HSP70, and HSP90), antioxidant-related genes (SOD1, SOD2, GPX1, GPX3, PRDX1, and TXN), tight junction-related genes (CLDN1, and OCLN), and immune-related genes (IL4, MUC2) in the ileum as compared to the HS group. The microbiota analysis showed significant enrichment of Bacillales, Christensenellaceae, Bacillaceae, Peptostreptococcaceae, and Anaerotruncus in heat-stressed birds supplemented with DP as compared to the HS group. Further, DP supplementation also significantly increased the concentration of acetate, propionate, and total VFA in the cecal digesta of the HS+DP group as compared to the HS group. Conclusion:These findings suggest that DP supplementation effectively improved the growth performances and gut health parameters in the heat-stressed birds. Thus, drie