Cellular antioxidant mechanism of selenium-enriched yeast diets in the protection of meat quality of heat-stressed hens

The effects and mechanisms of dietary selenium-enriched yeast (SeY, at Se 0, 0.25, and 0.50 mg/kg) on breast meat quality and oxidative stability of heat-stressed laying hens were studied. Two hundred and forty healthy Jingbai cross-bred hens at late laying period were randomly assigned to 4 experimental groups: one control group reared in a controlled thermal environment, and three treatment groups reared with heat stress (HS). The birds assigned to the controlled thermal environment were fed the basal diet, and the birds in the HS groups were fed the basal diet supplemented with 0, 0.25, or 0.50 mg Se (as SeY)/kg diet for 28 days. Chronic HS decreased pH_45min, increased lightness and drip loss, and impaired postmortem oxidative stability of breast muscle. The inclusion of SeY effectively reduced these stress-induced negative impacts, particularly on paleness, drip loss, and pH_45min decline. The SeY significantly enhanced the cellular antioxidant defense system, suppressed the reactive oxygen species (ROS) overproduction, and mitigated the mitochondrial damage and apoptosis of stressed muscle. In conclusion, dietary modification with SeY reduced quality loss and oxidative instability of meat from heat-stressed hens by maintaining a balanced mitochondrial redox status and inhibiting ROS induced myocyte apoptosis.