Effect of Dietary Vitamin E on Cortisol and Glucose Responses to Handling Stress in Juvenile Beluga Huso huso

Abstract

An 8-week feeding experiment was conducted to investigate the effect of dietary vitamin E on the physiological response to handling stress in juvenile beluga Huso huso. Fish were fed six experimental diets supplemented with 0, 25, 50, 100, 200, or 400 mg Dl-all-rac-α-tocopherol acetate/kg diet. At the end of the experiment, the fish in each tank were subjected to acute handling and air exposure stress. Cortisol and glucose were measured as the primary hormonal and secondary metabolic responses to the stressors, both before and 3 h after application of the stressors. The growth parameters and feed utilization rates were significantly lower in fish fed the diet not supplemented with vitamin E than in fish fed diets supplemented with vitamin E. Cortisol concentration was not affected by dietary treatment but glucose concentration was. Fish fed vitamin E at 0, 25, 100, and 400 mg/kg diet had higher concentrations of glucose than those fed vitamin E at 50 and 200 mg/kg. However, fish fed diets with 50 and 200 mg/kg exhibited higher growth rates. These results indicate that dietary vitamin E has some effect on plasma glucose but no effect on plasma cortisol. In general, when the stressors were applied to belugas, the glucose and cortisol responses were relatively low. This may be due to higher resistance and lower physiological responses to these types of stressors by this species or by chondrosteans in general.

Received January 10, 2011; accepted August 4, 2011

ACKNOWLEDGMENTS

We thank the staff at the Shahid Dr. Beheshti Sturgeon Propagation and Rearing Complex for providing the juvenile beluga sturgeon and the necessary facilities for this experiment.