Zinc retention in rabbits: effect of previous diet

The retention of orally administered zinc-65 was influenced by the previous diet. Zinc-deficient rabbits fed a diet containing 25 parts of zinc per million incorporated naturally in soybean protein still retained 58 percent of an oral dose of zinc-65 16 days after the dose was given, while rabbits fed the same diet supplemented with zinc (54 parts per million) as zinc oxide retained only 14 percent. The weight gain and the appearance of the animals fed these two diets were different.