The Domestic Cat as a Laboratory Animal for Experimental Nutrition Studies III. Niacin Requirements and Tryptophan Metabolism

Niacin deficiency, characterized by loss in body weight, diarrhea and death, has been produced in cats fed a 35% casein diet. Doses of 1 to 3 mg of niacin are effective against the deficiency; the optimum appears to be 10 mg or more. Tryptophan supplements are not effective either in promoting growth or in bringing about urinary excretion of N 1 -methyl-nicotinamide. Cats deficient in pyridoxine do not excrete xanthurenic acid following supplementation with tryptophan. It is concluded that in the cat the metabolism of tryptophan is different from that in other species, at least from the kynurenine stage onward.