Protein minimum requirements from some vegetable sources for maintenance of mature laboratory rats

Abstract

The effect of the quality and quantity of dietary protein on its utilization and on requirement by adult rats was studied by means of biological and biochemical parameters. Wistar adult rats were fed, "ad libitum", isocaloric diets containing various levels of casein (1%, 3%, 5%), rice (3%, 6%, 7%), bean (5%, 7%, 9%) and a rice and bean mixture (3%, 6%, 8%) throughout the 28 days period, and were compared to a casein control group (28%). The dietary protein levels to maintain body weight for adult rats were 4.1 g%; 9.7 g%; 7.3 g% and 4.5 g% for rice, bean, rice-bean mixture and casein, respectively. Biochemical parameters (plasma protein, albumin and liver protein) were not a sensitive indicator of protein intake. The magnitude of the changes observed shows a metabolic adaptation to protein restriction and possibility to overcome the poor protein quality by increasing the dietary protein quantity. The extent to which protein quality affects protein utilization depends on the stage of the animal physiological development.