Valorization of rapeseed meal. 2. Nutritive value of high or low-glucosinolate varieties and effect of dehulling

Five groups of 12 growing rats each were fed a control diet or one of 4 experimental diets composed of either high glucosinolate (Jet Neuf) or low glucosinolate (Tandem) rapeseed meal. After a 3-day adaptation period, the rats were fed ad libitum for 15 days. Both meals were given dehulled or non-dehulled. The Tandem rapeseed meal provided all the protein and Jet Neuf half the protein of the corresponding diets. Dehulling the seeds significantly increased the energy and protein digestibility of the rapeseed meals (+ 16.5 and + 6.3 or 10.4 points, respectively), their digestible energy and digestible protein contents (+ 28 and + 30%) and metabolic utilization of digestible protein in the indirect nitrogen balance trial. Conversely, in the feeding trial, the feed efficiency of the dehulled meal diets was lower than that of the non-dehulled meal diets. However, dehulling the Tandem rape seeds did not seem to reduce lysine availability. Finally, feeding dehulled Tandem rapeseed meal as the sole protein source did not significantly increase the liver weight of the rats.