Effects of Deficient Zinc Intake on Palatability of Lard and Fish-oil Diets in Rats

Abstract

This study examined the effect of deficient zinc intake on the palatability of lard and fish-oil diets. Four-week-old male Fischer 344 rats were fed one of four diets: zinc-deficient lard diet （－ZnLD）, zinc-deficient fish-oil diet （－ZnFD）, zinc-adequate lard diet （＋ZnLD）, zinc-adequate fish-oil diet （＋ZnFD）. After 3 weeks, six rats in each group were dissected. The remaining －Zn rats were placed on a two-choice diet program of －ZnLD and －ZnFD, and the ＋Zn rats were placed on a two-choice diet program of ＋ZnLD and ＋ZnFD. After the self-selection period, all rats were dissected. Throughout the experimental period, the －Zn groups showed significantly low plasma zinc concentrations, food intake, and body weight, compared to the ＋Zn groups. The plasma and hepatic lipid levels were also lower in the －Zn groups. While the ＋Zn groups selectively ingested LD and FD at an n-6/n-3 ratio of approximately 3, the n-6/n-3 ratio was 1.9 in the －ZnLD group and 6.6 in the －ZnFD group. These results suggest that the ＋Zn groups were capable of taking in essential fatty acids at a fixed n-6/n-3 ratio, and that deficient Zn intake appeared to reduce this ability.