Interaction between dietary thiamine and lipid in juvenile steelhead trout

Abstract

Thiamine (vitamin B1) deficiency has been negatively affecting salmonines in the Great Lakes region. This project investigated the hypothesis that thiamine deficiency in steelhead trout is a result of a high lipid diet due to thiamine being used up as an antioxidant to prevent lipid peroxidation. Juvenile steelhead trout were fed four diets (high lipid/thiamine, high lipid/no thiamine, low lipid/thiamine, and low lipid/no thiamine) in triplicate aquaria over a six-week period. Fish were sampled every two weeks to assess survival and growth, and samples were preserved for biochemical analysis. At week six, weight and lipid content of fish fed low lipid diets differed significantly from fish fed high lipid diets regardless of the presence or absence of dietary thiamine (P<0.05). Thiamine concentrations in fish fed the thiamine-containing diets were significantly higher than those fed thiamine deplete diet (P<0.05). Mortality was the highest in fish fed low lipid/no thiamine diet, followed by fish fed the low lipid/thiamine, high lipid/no thiamine, and then high lipid/thiamine diets. Finally, fish fed the high lipid/no thiamine diet began to exhibit symptoms of thiamine deficiency during week 4 of the experiment.