[Zn-binding capacity of serum. A parameter for diagnosing marginal Zn deficiency (author's transl)]

In two experiments with male Sprague-Dawley rats, the influence of varying the dietary Zn content on per cent Zn-binding capacity of the serum was to be measured. In the first experiment, young rats were given, after a 14-day Zn depletion, the following diets with 1.3, 4, 6, 8, 10, 12, 20, and 100 mg Zn/kg DM for 2 weeks. Per cent Zn-binding capacity of the serum was 90% in the extreme deficiency range and decreased to less than 60% with increasing dietary Zn content, whereas the serum Zn content rose steadily with the Zn supply. Following Zn injection, per cent Zn-binding capacity of the serum significantly decreased to values around 70% in all animals of the groups given 1.3--12 mg dietary Zn. At 20 and 100 mg/kg of diet, per cent Zn-binding capacity of the serum was not affected by Zn injection. In the second experiment, per cent Zn-binding capacity of the serum was also found to depend upon Zn supply without prior depletion in rats of three different age groups with life weights of 50, 100, and 300 g. Under these experimental conditions, per cent Zn-binding capacity of the serum proved to be a good indicator for diagnosing alimentary Zn supply.