Effects of zinc deficiency on food intake and feeding patterns of rats.

I. The effects of alterations of the protein and zinc concentrations of a semi-synthetic diet on the food intake and dietary preferences of Zn-deficient and normal rats have beencompared. 2. The voluntary food intake of Zn-deficient rats fell to 70 96 of that of the controls. The day-to-day variation of intake increased markedly and was associated with a cyclical pattern of food consumption. When the food intake of deficient rats was slightly restricted the troughs of the cycles disappeared. 3. Concurrent with the fall in food intake, Zn-deficient rats ceased to gain weight, but a similar change was found with pair-fed controls. 4. Force-feeding Zn-deficient rats with 140 yo of their voluntary intake rapidly induced signs of ill-health. 5. Reduction of the protein content of the diet from 20 to 5 % resulted in an increased food intake and the disappearance of the cyclical pattern of intake. Growth, however, was not renewed. 6. Zn-deficient rats responded to a Zn-supplemented diet within 1-2 h by an increased food intake.