Vitamin E requirements of juvenile grass shrimp, Penaeus monodon, and effects on non-specific immune responses.

A feeding trial was conducted to determine the dietary vitamin E (DL-alpha-tocopheryl acetate, dl-alpha-TOA) requirement and its effect on the non-specific immune responses of juvenile grass shrimp, Penaeus monodon. Purified diets with eight levels (0, 25, 50, 75, 100, 150, 200, 400 mg vitamin E kg diet-1) of supplemental dl-alpha-TOA were fed to P. monodon (mean initial weight 0.29 +/- 0.01 g) for eight weeks. Each diet was fed to three replicate groups of shrimp. Weight gains and total haemocyte count (THC) were higher (P < 0.05) in shrimp fed diets supplemented with 75 and 100 mg vitamin E kg diet-1 than in shrimp fed diets supplemented with </= 50 mg vitamin E kg diet-1. Superoxide dismutase (SOD) activity was higher in shrimp fed diets supplemented with 50-200 mg vitamin E kg diet-1 than in shrimp fed diets supplemented with </= 25 and 400 mg vitamin E kg diet-1. Vitamin E concentrations in the hepatopancreas and muscle of the shrimp were increased as the dietary vitamin E supplementation level was increased up to 200 mg vitamin E kg diet-1. Thiobarbituric acid (TBA) values in the hepatopancreas and muscle were generally decreased as the dietary vitamin E supplementation level increased. Analysis by polynomial regression of weight gain, THC and hepatopancreatic vitamin E concentration of the shrimp indicated that a level of 85-89 mg vitamin E kg diet-1 is required for maximal growth and non-specific immune responses of P. monodon and that 179 mg vitamin E kg diet-1 is required to maximise tissue vitamin E concentration.