DETOXIFICATION OF RAPESEED MEAL BY EXTRUSION WITH AN ADDED BASIC SALT

A commercial, high-glucosinolate, rapeseed meal with no added salt or mixed with 2, 5, or 10% NH4HCO3 was extruded under different processin g conditions using the Wenger TX-52 twin-screw extruder. Male Wistar r ats were fed 13 diets containing 15% rapeseed meals (including nonextr uded) or a casein-based control diet. After six weeks, blood samples w ere taken, and serum was analyzed for thyroid hormones. Extrusion proc essing under all salt and steam conditions tested reduced glucosino-la te levels in the meal, but no significant correlation was found betwee n intensity of the treatment conditions and glucosinolate reduction. H igher weight gains, feed efficiencies, and thyroid hormone profiles we re observed with use of the extruded meals; but no treatment completel y detoxified the meal. Histopathological evaluation showed that thyroi d and other tissue abnormalities occurred in all animals except those fed the casein diet. Antinutrients, including glucosinolates and proba bly volatile nitriles, in the meal were reduced by extrusion processin g under the basic conditions of this experiment.