Nutritional effects of field bean (Vicia fabaL.) proteinase inhibitors fed to rats

Abstract

1. Weanling rats were fed on purified-casein diets containing active and inactive (autoclaved) field bean (Vicia fabaL.) proteinase inhibitors (PI) at levels of 1.25, 2.5, 5.0 and 10 g/kg. Diets containing raw-and autoclaved-field-bean meal (FBM) were also given. The body-weight gain, protein efficiency ratio (PER); i.e. the ratio of the live weight gain in g/g of protein consumed and apparent nitrogen digestibility were determined 7, 14 and 21 d after the start of the trial.2. Significant growth depression (P< 0.001) was observed in rats given diets containing 2.5 g/kg PI (27–35%). In rats fed on raw FBM growth depression was severe after 7 d (57%).3. Food intake was depressed at PI inclusion levels of 5 g/kg and higher between 14 and 21 d.4. PER was depressed significantly (33–44%) in rats given diets containing the active PI at all levels after 7 d. The protein utilization of all casein diets was higher than that of the FBM diets.5. Apparent N digestibility was depressed in rats fed on diets containing 10 g/kg PI by 9 and 7% at 14 and 21 d respectively. The N digestibility of both raw and heated FBM was similar at approximately 84%.6. It was concluded that the PI are not the main factors responsible for the growth depression observed when raw FBM is fed to rats.