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EVALUATING PROTEIN QUALITY BY ESTIMATING WEIGHT GAIN COEFFICIENTS
Author(s) -
CANOLTY NANCY L.,
KOONG L. J.
Publication year - 1977
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1977.tb12686.x
Subject(s) - weight gain , protein quality , weanling , body weight , zoology , linear regression , biology , chemistry , food science , mathematics , endocrinology , statistics
A different approach was used to evaluate protein quality in this study. Varying amounts of isonitrogenous (1.6%) diets containing lactalbumin, commercially prepared nondefatted corn germ or isolated soybean protein were fed to weanling rats for 3 wk. Body weights were recorded weekly and feed intakes determined daily. Body weight change and feed intake (dry matter) of each rat were expressed as per kg metabolic body size (mean body weight, kg 0.75 ). Weight change was related to feed intake by linear regression with the slope of the regression line being designated as the weight gain coefficient. A weight maintenance coefficient was determined for each diet by calculating from the appropriate regression equation the feed intake that maintained body weight. When the three diets were compared, there were no differences among the weight maintenance coefficients indicating that the three diets were equally effective in maintaining body weight. There were differences among the weight gain coefficients, however, demonstrating that the three diets were not equally effective in promoting growth. Since diets were isonitrogenous, differences among weight gain coefficients were attributed to differences among proteins. We propose that weight gain coefficients are directly related to protein quality when diets differ only with respect to the source of protein and suggest that there are distinct advantages in using this method for evaluating protein quality.