Nitroblue Tetrazolium Reduction of Neutrophils in Heat Stressed Goats Is Not Influenced by Selenium and Vitamin E Injection

Abstract

Experiment was designed to determine whether heat stress suppresses neutrophil function and injections of selenium and vitamin E prior to heat stress prevent suppression of neutrophil function in goats. Twelve female goats were divided into 2 groups of 6 each and were kept at 25°C. Goats in the treatment group were injected intramuscularly with 0.1 mg/kg of selenium and 2.72 IU/kg of vitamin E at 8 and 1 day prior to the initiation of heat stress. The other group was kept as control. All goats were exposed to hot environment at 38°C from day 0 through 8. Decreased tendency in plasma cortisol concentrations and temporary increase in plasma glucose concentrations were shown in both groups. In the control group, plasma selenium concentration gradually increased and a-tocopherol concentration decreased during the first 2 days. After the second injection with selenium and vitamin E, plasma selenium and a-tocopherol concentrations significantly increased and remained higher than those in the control group. Whole blood glutathione peroxidase (GSH-Px) activity in the treatment group tended to be greater than that in the control group, but no significant difference was observed between 2 groups. The nitroblue tetrazolium (NBT) reduction by activated neutrophils significantly decreased on day 6 in the control group but not in the treatment group. The NBT reduction by resting neutrophils significantly decreased in both groups. These data suggest that heat stress depresses neutrophil function, and selenium and vitamin E injection prior to heat stress has no apparent effect on neutrophil function during the stress.