Food intake regulation in the weanling rat: self selection of protein and energy

Abstract

Four experiments were designed to measure the ability of the weanling rat to regulate protein intake. The rats were allowed to self select their food intake from choices of two diets varying only in protein content. The amount of protein energy selected was measured when they were fed a choice of diets varying in protein quantity (0 to 70%) and quality (casein or gluten) or in protein density (the diets were diluted by 15 or 30% with cellulose) and when they were fed in the cold (8°). For each protein source, the protein intake in relation to total energy was constant as a result of appropriate selection from the diets offered. A higher ratio of dietary protein energy was selected when the poor quality gluten rather than casein was fed. The gluten fed rats given a choice of a 50% gluten diet and a protein free diet maintained a constant intake of protein even when the gluten diet was diluted with cellulose. Cold exposed rats fed a choice of a casein diet and a protein free diet made appropriate adjustment for their increased energy requirement by eating the protein free diet. It is concluded that the weanling rat exhibits evidence of a definite ability to regulate protein intake. The mechanisms controlling protein intake and energy intake, while apparently separate, interact to control food intake.