Protein Efficiency Ratio of Pigeon Pea (Cajanus cajan) and Lima Bean (Phaseolus lunatus): A Sprague-Dawley Rat Growth Assay

Abstract

Objective. This study has been conducted to determine the protein efficiency ratio (PER) of selected indigenous legumes, namely pigeon pea (Cajanus cajan) and lima bean (Phaseolus lunatus), as alternative protein sources.
 Methods. Experimental diets (pigeon pea-based and lima bean-based) and control diet (casein-based) were formulated and standardized using proximate analysis to have 10% protein basal diet based on the Association of Official Analytical Chemists (AOAC) guidelines. Diets were given to corresponding groups (2 experimental, 1 control) using 30 albino Sprague-Dawley weanling rats aged 21 days old, over a 28-day growth assay.
 Results. Results showed that the mean final weight and weight gain were significantly higher in rats fed with caseinbased diet (p<0.05 for both parameters) compared to those fed with pigeon pea-based diet and lima bean-based diet. The two experimental groups showed no significant difference between their mean final weights and weight changes (p=1, p>0.05). The PER of the casein (3.37 ± 2.71) is higher than that of the pigeon pea (1.87) and lima bean (1.32). These results can be attributed to the presence of anti-nutritional factors (ANFs) in the seeds of pigeon pea and lima bean. Reduced protein intake (due to bitter taste), toxicity, and interference with protein digestibility (through interaction with digestive enzymes) imparted by these ANFs can explain the weight loss among the experimental groups and consequently the low PER. Heat treatment done in the study were not adequate to remove the ANFs.
 Conclusion. The study shows that pigeon pea and lima bean as protein sources alone are not as adequate and efficient in providing necessary protein requirements for weanling rats. Proper processing and treatment should be done to remove inhibitors of protein digestibility and quality.