Rats allowed to self-select zinc-deficient lard and fish-oil diets did not develop a preference for fish-oil diet.

Zinc (Zn)-deficiency causes a reduction in food intake and alters adipose metabolism. The effect of zinc restriction in rats on the selection of fish-oil and lard was studied during a period of reduced appetite. The reduction of appetite was caused by an experimentally induced Zn-deficiency. Four-week-old male rats were divided into three dietary treatment groups: Zn-adequate (ZnA, 30.9 mg Zn/kg), marginal Zn-deficient (ZnM, 5.9 mg Zn/kg) or Zn-deficient (ZnD, 0.9 mg Zn/kg). The three groups were placed on a self-selection regimen of the ZnA-fish-oil diet (ZnA-FD) and the ZnA-lard diet (ZnA-LD), the ZnM-FD and the ZnM-LD or the ZnD-FD and the ZnD-LD, respectively for 24 d. The amount of the FD intake in the ZnD group decreased to 0.5 g/d after day 4-6 of self-selecting on the LD and the FD and no significant increase in the FD intake in the group was observed during the self-selection period. However, after day 7-9 and 13-15, the FD intake of the ZnA and the ZnM groups increased, respectively, and at the end of the self-selection period the ZnM and the ZnA rats consumed about 2.0 g FD/d and 4.5 g FD/d, respectively. The FD intake ratio [FD intake (g)/total intake (g)] in the ZnD rats during the self-selection period was the lowest and that in the ZnA rats was the highest of three groups. In conclusion, we showed that zinc status alters fish-oil and lard selection patterns and ZnD rats did not show a preference for fish-oil.