MITIGATION OF HEAT STRESS IN POULTRY USING DRIED PLUM OR ALPHA-LIPOIC ACID SUPPLEMENT

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2020

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Introduction: Heat stress is a significant problem in the poultry industry, causing a severe economic loss due to its detrimental effect on the health and performances of chickens. Dried plum (DP) is a good source of minerals, vitamins, antioxidants, and phenolic compounds, and plays a role in calcium homeostasis and cardiovascular dysfunctions. Alpha-lipoic acid (ALA), on the other hand, is water and fat-soluble antioxidant, which can be readily absorbed from the intestine resulting in maximum bioavailability. Moreover, ALA acts as a coenzyme in glucose metabolism and helps generate other antioxidants. Considering these health benefits and properties, we hypothesized that the dietary supplementation of DP or ALA would help to mitigate heat stress in poultry. Objectives: The purposes of this study were to: 1) to determine the effects of DP supplementation on growth performance, gut health and immune parameters of heat-stressed broiler chickens, and 2) to determine the effects of ALA supplementation on growth performance, gut microbiota, gut health and immune parameters of heat-stressed broiler chickens. Methods: Study 1: Day-old Cob-500 unsexed chicks (n=72) were randomly placed into three treatment groups (n=24/group): No heat stress (NHS), 2) Heat stress with basal diet (HS), and 3) Heat stress with dried plum (HS+DP). Birds were raised under the standard broiler rearing guidelines for the first 21 days. Afterward, birds in the HS and HS+DP groups were exposed to heat stress conditions (33°C for 8 hours during daylight) for 3 weeks, while those in those in the NHS group were reared under normal conditions. Inclusion of 2.5% DP was made on the diet of the HS+DP group from 14 d onwards. Weekly body weight and feed intake were measured to calculate the average daily growth rate (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). On day 42, birds were euthanized, a portion of ileum was excised for the gene expression and histomorphometry analysis. Cecum digesta was collected for the volatile fatty acids (VFAs) and microbial population analysis using 16S rRNA sequencing. Study 2: Day-old Cob-500 unsexed chicks (n=72) were randomly placed into three treatment groups (n=24/group): No heat stress (NHS), 2) Heat stress with basal diet (HS), and 3) Heat stress with alpha-lipoic acid (HS+ALA) and were reared under the standard broiler rearing guidelines for the first 21 days. Afterward, birds in the HS and HS+ALA groups were exposed to heat stress conditions (33°C for 8 hours during daylight) for 3 weeks, while those in the NHS group were reared under normal conditions. Supplementation of ALA (500 mg/kg) was made on the diet of the HS+ALA group from 14 d onwards. All other experimental procedures and analyses were carried out as mentioned in the DP study. Results: Study 1: Supplementation of DP in the heat-stressed broilers significantly improved the final body weight, ADG, ADFI, efficiency; the expression of heat shock protein-related genes (HSF1, HSF3, HSP70, HSP90), antioxidant-related genes (SOD1, SOD2, GPX1, GPX3, PRDX1, TXN), tight junction-related genes (CLDN1, OCLN), immune-related genes (IL4, MUC2) and major VFAs. The microbial analysis revealed significant enrichment of beneficial bacteria in DP supplemented broilers. Study 2: Supplementation of ALA in the heat-stressed broilers significantly improve the final body weight, ADG, expression of HSP90, PRDX1, GPX3, SOD2, OCLN, MUC2, and major VFAs. Finally, the microbial analysis revealed the significant abundance of beneficial bacteria Lactobacillus and Peptostreptococcaceae in the ALA supplemented broilers. Conclusion: This study identified dietary supplementation of DP to be the novel strategy to mitigate heat stress in poultry. Dietary supplementation of the DP improved both the growth performance and overall gastrointestinal physiology in heat-stressed broilers. Similarly, ALA improved body weight, gut microbiota, and other gut health parameters. Thus, the DP, and ALA supplementation can be considered as a potential remedy for heat stress in poultry.

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Animal sciences, Agriculture, Alpha-lipoic acid, Dried plum, Heat stress, Microbiota, Mitigation, Poultry

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133 pages

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