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

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 % 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. 7. Zn-deficient rats were able to discriminate between diets containing 6 and I ppm Zn when both diets were offered simultaneously. 8. The responses of Zn-deficient rats to Zn-containing diets did not occur if the diets did not contain protein.