Production of Zinc Deficiency in the Squirrel Monkey (Saimiri sciureus)

Zinc deficiency was produced in the squirrel monkey by feeding a low zinc diet containing casein as the protein source. The casein was rendered low in zinc by a procedure combining isoelectric precipitation and treatment with disodium ethylenediaminetetraacetic acid (Na2 EDTA). The diet was tested in two experimental trials, in which eleven, weanling, male squirrel monkeys were fed the diet for periods up to 352 days and were compared with eleven control monkeys fed the same diet supplemented with 15 µg zinc/g. Growth in monkeys fed the low zinc diet was retarded; the animals became unkempt in appearance, and some showed varying degrees of hair loss. Hair samples obtained on days 22–23 of feeding showed decreased zinc concentrations. Red cell volumes and red cell hemoglobin concentrations, determined serially until days 56–57, were normal. At killing, reduced zinc concentrations were found in the heart, spleen, liver, and pancreas. In the adrenal, zinc concentration was increased, while in bone it was normal. Three monkeys fed the low zinc diet for more than 130 days showed decreased concentrations of serum albumin and zinc.