Dietary components and gastrointestinal growth in rats

Groups of young rats, weighing 50--80 g, were fed nutritionally adequate purified diets containing different types of protein, carbohydrate, lipid and fiber, or no fiber. Effect of diet on growth of the gastrointestinal tract was evaluated from differences in size of the organs and organ weight: body weight ratios at the end of a 5 week feeding period. The results suggested that type of dietary protein (casein or soy protein), or carbohydrate (dextrose, sucrose, hydrolyzed starch), or lipid (mixed animal + vegetable, corn oil or lard) did not seem to influence growth of the stomach, small intestine, cecum or colon. However, fiber (mixed vegetable, from oats or cellulose) in the diet appeared to have enhanced growth of the small intestine, and more markedly that of the colon (both its length and weight) but not that of the stomach or cecum. On the basis of crude fiber, growth enhancement appeared to be greater in response to the diet with mixed animal and vegetable components than to the semi-purified diets containing oats or cellulose.