Protein Quality Indices and Growth Performance of Albino Rats Fed Sprouted Soybean, African Yam Bean and Red Kidney Bean Diets

The search for sustainable plant-based protein sources has intensified due to the increasing prevalence of protein-energy malnutrition and the rising cost of animal proteins. Sprouting is an effective bioprocessing technique known to improve the nutritional quality and digestibility of legumes by reducing anti-nutritional factors and enhancing nutrient bioavailability. This study evaluated the influence of sprouted soybean (Glycine max), African yam bean (Sphenostylis stenocarpa), and red kidney bean (Phaseolus vulgaris) protein diets on protein quality indices and growth performance in albino rats. Soybean, African yam bean, and red kidney bean seeds were sprouted for 48 h, oven-dried at 55 °C, milled into flour, and blended in nine different proportions. Experimental diets were formulated to contain 10% crude protein and fed to groups of albino rats for 21 days, while commercial rat chow served as the control. Growth performance was evaluated using feed intake, body weight gain, feed efficiency ratio, and protein efficiency ratio. Protein quality was assessed using apparent protein digestibility, nitrogen balance, biological value, net protein utilization, and net protein ratio following standard nitrogen-balance procedures. Data were analyzed using one-way analysis of variance, and treatment means were separated using Duncan’s multiple range test at p < 0.05. Significant (p < 0.05) differences were observed among the dietary treatments for all growth-performance and protein-quality parameters. Rats fed the commercial control diet recorded the highest growth performance and protein-utilization indices. Among the experimental diets, the blend containing 50% sprouted soybean and 50% sprouted red kidney bean (LB5) produced superior values for several growth and protein-quality indices. The improved nutritional response observed in mixed-legume diets may be associated with complementary amino-acid profiles and the beneficial effects of sprouting on anti-nutritional factors and protein digestibility. The findings indicate that selected sprouted soybean–African yam bean–red kidney bean blends have potential as affordable plant-based protein ingredients for food-product development.