Feeding Diets Containing High Levels of Milk Products or Cellulose Decrease Urease Activity and Ammonia Production in Rat Intestine

Manuscript received 26 September 1997. Initial reviews completed 10 November 1997. Revision accepted 23 March 1998.

Department of Animal Science, Cheju National University, Cheju 690-756, Republic of Korea and ^* Departments of Meat and Animal Science and Nutritional Sciences, University of Wisconsin, Madison, WI 53706

Three studies were done to determine the effect of feeding diets containing high levels of a readily fermentable carbohydrate (lactose in milk or yogurt, or pure lactose) or an undigestible, unfermentable diluent (-cellulose) on urease (EC 3.5.1.5) activity and net ammonia production in the rat gastrointestinal (GI) contents. Rats (170-200 g) were fed a control diet or diets containing 55% dried milk or 55% dried yogurt, 25% lactose or 10% -cellulose. Feeding diets containing milk or yogurt decreased urease activity to ~11% of the control value in the small intestine (on the basis of grams of collected contents or total contents), and to 50% in the large intestine (only on the basis of grams of collected contents). Feeding the diet containing 25% lactose also decreased urease activity (on the basis of grams of collected contents or total contents) to about 20% of the control value in the small intestine, but not (P > 0.05) in the large intestine. Net ammonia production rate was correlated (r² = 0.98) with urease activity in the large intestinal contents, and the rate of ammonia production from ureolysis represented about two thirds of the total. Feeding the cellulose diet decreased (P < 0.05) both urease activity and net ammonia production in the large intestine to ~30% of the control value. Weights of tissue and contents of the large intestine were much higher (P < 0.01) in rats fed diets containing milk products or lactose than in the control rats, but were not affected by consumption of the cellulose diet. Results of our studies indicate that feeding diets containing high levels of milk products (lactose) or cellulose reduces urease activity and net ammonia production in the rat intestine, and thus may be beneficial for improving animal and human health.

The Journal of Nutrition Vol. 128 No. 7 July 1998, pp. 1186-1191
Copyright ©1998 by the American Society for Nutritional Sciences

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