Toxicity of water extracted rapeseed meal in the rat

The toxic effect of different concentrations of “detoxified” rapeseed meal (DRSM) obtained by 2 h lixiviation was studied. This preparation contained 0.02 % oxazolidinethiones (VTO) and no detectable isothiocyanates (ITC). It was fed for 4 weeks to weanling rats in amounts that provided from 0 to 100% of total dietary protein. The control diet provided 20% protein from casein. Another control group was fed crude rapeseed meal (RSM) to the same protein level. Growth rates and protein efficiency ratio (PER) were similar in rats fed DRSM and casein diets. The substitution of casein by increasing levels of DRSM did not modify PER. The weight of the liver, thyroid, heart, spleen, adrenals and kidneys was normal. In animals fed DRSM no histological changes were detected in the liver. The thyroid exhibited changes similar to, but of lesser severity than in animals fed crude RSM. It is suggested that other toxic compound(s) may be present in rapeseed meal that are not extractable by lixiviation. The need of further investigations of the effect of this “detoxified” product including functional studies before its extensive inclusion in animal or human diets is emphasised.