RAPESEED OIL MEAL AS A PROTEIN SUPPLEMENT FOR SWINE AND RATS: II. ENERGY AND NITROGEN DIGESTIBILITY AND NITROGEN RETENTION
Energy and nitrogen digestibility and nitrogen retention studies are reported for pigs averaging 7, 28 and 62 kg. in weight and for 4- and 6-weeks-old albino rats fed diets containing 0, 2 or 10 per cent expeller extracted Argentine type rapeseed oil meal. The 10 per cent level of the meal depressed apparent digestibility of dry matter, energy and nitrogen with significant effects occurring only in rats. The 2 per cent level of the meal had no significant effect on digestibility. Retention of digestible nitrogen was not altered by the level of rapeseed oil meal in the diet. As indicated by digestibility studies, female rats were more susceptible than males to the presence of rapeseed oil meal in the diet. There were a number of interactions between rapeseed oil meal level and the type of diet fed to rats suggesting that the energy and protein levels of the diet may influence the effect that this meal has on apparent digestibilities of dry matter, energy and nitrogen.