Dose-Dependent Enrichments and Improved Redox Status in Tissues of Broiler Chicks under Heat Stress by Dietary Supplemental Microalgal Astaxanthin

Astaxanthin (AST) is a well-known carotenoid with a high antioxidant capacity. This study was designed to evaluate the nutritional and metabolic effects of microalgal AST added to the diets of broiler chicks under heat stress. A total of 240 Cornish male chicks (1 day old) were divided into six cages per treatment (eight chicks per cage) and fed a corn-soybean meal diet supplemented with AST from Haematococcus pluvialis at 0, 10, 20, 40, and 80 mg/kg for 6 weeks. Heat stress was employed during weeks 4-6. The supplementation led to dose-dependent enrichments (P < 0.05) of AST and total carotenoids in the plasma, the liver, and the breast and thigh muscles. There were similar enhancements (P < 0.05) of oxygen-radicalabsorbance capacities, but there were decreases or mixed responses (P < 0.05) of glutathione concentrations and glutathione peroxidase activities in the tissues. In conclusion, supplemental dietary microalgal AST was bioavailable to the chicks and enriched in their tissues independent of heat stress, leading to coordinated changes in their endogenous antioxidant defense and meat quality.