Growth and nitrogen retention of rats fed bean ( Phaseolus vulgaris) and bean and rice diets

Abstract

The protein quality of bean diets was compared to the protein quality of bean and rice complementary diets in rat feeding studies assaying growth and nitrogen balance. Amino acid analyses of the diets indicated that methionine and cysteine were limiting in beans and lysine was limiting in rice. Weight gain of rats fed whole black beans either alone or in combination with rice was significantly smaller ( p ≤0·05) than the weight gain of rats fed dehulled black or white beans either alone or in combination with rice. Protein efficiency ratio (PER), feed efficiency ratio (FER) and relative PER (rPER) were significantly greater ( p≤0·05) for bean and rice diets than bean diets. Total serum protein concentration of rats was correlated ( r=0·63) with weight gain. True digestibility coefficient (DC), biological value (BV) and net protein utilization (NPU) of bean and rice diets were significantly greater ( p ≤0·05) than the DC, BV and NPU of bean diets. The DC, BV and NPU for the whole black bean diet were significantly smaller than the DC, BV and NPU of the other bean diets. The BV of bean and rice diet proteins were statistically similar ( p>0·05) to the BV of the control casein diet. In conclusion, the protein quality of beans was improved by combining with rice. Dehulling of whole black beans improved the protein quality of black beans to the same level as the protein quality of white beans when fed alone or in combination with rice.