Abstract
This paper describes a preference for two disaccharides in the diets of Zn-adequate and Zn-deficient rats. Maltose and sucrose were used as a source of carbohydrate in the diet and the selection patterns of rats were analyzed for 28 d by a two-choice selection method. Diets provided as a set of two either Zn-adequate or Zn-deficient diets were changed in position daily. Control Zn-adequate and Zn-deficient rats both exclusively selected the sucrose diet at days 1 and 2, after onset of the feeding experiment, and then gradually selected the maltose-diet. After changing their preference from sucrose to maltose, the Zn-adequate control rats selected widely from both the maltose and sucrose diets, while the Zn-deficient rats exclusively and continuously selected the maltose diet from the two diets over the experimental period. The level of selection of sucrose-diet on day 28 had a correlation with the intestinal sucrase activity in the control rats. The sum of daily maltose and sucrose diet intake in rats fed a Zn-deficient diet showed a characteristic variation with the cyclic period of 3.6±0.2 d. The daily body-weight change of rats fed a Zn-deficient diet was well synchronized with their own food intake cycle. The day before changing preference from sucrose to maltose in rats fed a Zn-deficient diet represented a trough in their own food intake and body-weight cycles. These results suggest that one sign of a change in preference from sucrose to maltose in Zn-deficient rats is caused by a stage of negative energy balance.
