NUTRITIONAL EVALUATION OF EXTRUDED FULL-FAT SOYBEANS AND RAPESEEDS USING PIGS AND CHICKENS

Abstract

Soybeans and rapeseeds were ’extruded’ at temperatures of 125 and 120 C, respectively. These products, along with soybean meal and rapeseed meal were substituted for 40% of a basal diet; the basal and substituted diets were fed to barrow pigs from 25 to 75 kg liveweight. Digestibility determinations, carried out when the pigs weighed 30 and 70 kg showed that the apparent digestibilities of dry matter, fat and nitrogen were not influenced by the weight of the pig; however, crude fiber was better digested by the 70-kg than by the 30-kg pigs. Apparent digestibilities of dry matter and gross energy of the diet containing rapeseed meal were less than those for the other diets. Digestible energy values of soybean meal and extruded soybean were 3.88 and 4.31 kcal/g, respectively, for the 30-kg pigs. Corresponding values for the rapeseed meal and extruded rapeseed were 2.93 and 4.83 kcal/g, respectively. Backfat of the pigs that had received the diet containing extruded soybeans contained significantly more linoleic acid (27%) than that from the pigs which had received the basal diet (14%). There was 3% erucic acid in the backfat sample of the pigs that had received the diet containing the extruded rapeseed. Addition of raw rapeseed to a basal diet reduced weight gain of young chicks, but this effect could be partially alleviated by extruding the rapeseed, in that the addition of 10% extruded rapeseed did not reduce performance significantly.