Control of food intake in the rat by dietary protein concentration.

Male, weanling Sprague-Dawley rats were fed isocaloric diets containing graded levels of protein or amino acid mixtures. Food intakes and weight gains were recorded daily or every other day. Both short-term and long-term (64 days) experiments were carried out. Linear regressions of food intake versus time and weight gain versus time were used to establish daily weight gains and food intakes. The four-parameter mathematical model for physiological responses was used to predict daily food intake, daily weight gain, daily food intake per 100 g weight and efficiency of food conversion (daily weight gain/daily food intake) as functions of dietary protein concentration. The changes in the four parameters generated from the four-parameter model were examined as a function of time. Several aspects of food intake, weight gain and efficiency were shown to be functions of concentration of dietary protein.