Effect of Dietary Rapeseed Meal on the Serum Proteins of Rats

Two experiments were conducted in which growing male rats were fed three diets containing as protein sources, casein (C), rapeseed meal variety Bronowski (BM), and B. napus meal (NM). In the first experiment the diets were fed to both thyroidectomized rats and to sham-operated rats with thyroid intact. Poorest gains were recorded for rats fed the NM diet irrespective of whether the thyroids were removed or intact, indicating that the toxicity of B. napus meal was not confined to the effect on the thyroid gland. In the second experiment four groups of rats were fed BM diet, NM diet, and C diet. The latter diet was given to both thyroidectomized rats and rats with intact thyroid to provide controls for the study of the effect on the thyroid of the glucosinolate in rapeseed. As in experiment 1, weight gain of rats receiving NM diet was less than that of either of the two groups of rats receiving C diet. After 25 days the serum protein and the thyroxine-binding properties of serum proteins were examined by disc gel electrophoresis. Rats fed NM or C diet (with thyroid removed) showed an altered serum protein pattern as compared to rats fed C or BM diets. The 131I-thyroxine-binding ability of the albumin band was much greater for the serum of rats receiving diets NM and C (with thyroid removed), 37% and 46% versus 22% of the total 131I-thyroxine recovered on the gel.