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 total food intake.