Influence of weed seed oil contamination on the nutritional quality of diets containing low erucic acid rapeseed (Brassica napus, Tower cultivar) oil when fed to rats.

Oils from three samples of rapeseed screenings and a sample of stinkweed seeds (Thlaspi arvense) were added to Tower rapeseed oil at three levels (5, 10 and 15%). The contaminated Tower oils were fed at 20% (w/w) of a purified diet to male weanling Sprague-Dawley rats for 16 weeks. The screenings oils caused no increase in the focal myocardial lesion index or lipidosis of the rat hearts. Stinkweed oil gave a significant increase in myocardial lipidosis and a non-significant increase of the myocarditis index. These were attributed to an imbalance in the fatty acid composition of the Tower oil for the specific requirements of the growing rat. Screenings oil contamination had no significant effects on the feed intake or growth of the animals. The growth of rats fed stinkweed oil-contaminated diets was significantly lower than other treatments when it was adjusted for feed intake by analysis of covariance. No treatment effects on body organ weights nor on blood lipid parameter were observed. The presence of week seed oils, at the highest levels likely to be encountered in low erucic acid rapeseed oil, was concluded to have a significant influence on its nutritional value.