FEEDING DIETS CONTAINING HIGH-LEVELS OF MILK-PRODUCTS OR CELLULOSE DECREASE UREASE ACTIVITY AND AMMONIA PRODUCTION IN RAT INTESTINE

Three studies were done to determine the effect of feeding diets conta ining high levels of a readily fermentable carbohydrate (lactose in mi lk or yogurt, or pure lactose) or an undigestible, unfermentable dilue nt (alpha-cellulose) on urease (EC 3.5.1.5) activity and net ammonia p roduction in the rat gastrointestinal (GI) contents. Rats (170-200 g) were fed a control diet or diets containing 55% dried milk or 55% drie d yogurt, 25% lactose or 10% alpha-cellulose. Feeding diets containing milk or yogurt decreased urease activity to similar to 11% of the con trol value in the small intestine (on the basis of grams of collected contents or total contents), and to 50% in the large intestine (only o n the basis of grams of collected contents). Feeding the diet containi ng 25% lactose also decreased urease activity (on the basis of grams o f collected contents or total contents) to about 20% of the control va lue in the small intestine, but not (P > 0.05) in the large intestine. Net ammonia production rate was correlated (r(2) = 0.98) with urease activity in the large intestinal contents, and the rate of ammonia pro duction from ureolysis represented about two thirds of the total. Feed ing the cellulose diet decreased (P < 0.05) both urease activity and n et ammonia production in the large intestine to similar to 30% of the control value. Weights of tissue and contents of the large intestine w ere much higher (P < 0.01) in rats fed diets containing milk products or lactose than in the control rats, but were not affected by consumpt ion of the cellulose diet. Results of our studies indicate that feedin g diets containing high levels of milk products (lactose) or cellulose reduces urease activity and net ammonia production in the rat intesti ne, and thus may be beneficial for improving animal and human health.