Protein evaluation of mixed diets in young adults, growing pigs, and growing rats

The protein quality of mixed diets was tested using the nitrogen balance technique with a slope-ratio approach in adults, growing pigs, and rats. For diet A (milk, cereals, potatoes, meat, fish, and vegetables) and diet B (milk, cereals, and potatoes) the slope of the regression line, nitrogen balance = f (nitrogen intake) was calculated and expressed in percentage of the slope obtained for diets containing egg white protein. In man, diet A was significantly better than the egg white protein diet which was similar to diet B. In pigs, diets A and B were significantly better than egg white protein. In rats, egg white protein was significantly better than diets A and B. The results are of interest in relation to the recommendations by FAO/WHO regarding adjustment of protein allowance in relation to dietary protein quality.