Selected features of copper metabolism in the cat

In separate experiments, domestic short hair kittens were fed diets based on soy or egg white protein containing from 1.98 to 9.64 or 0.58 to 9.8 micrograms Cu/g diet, respectively. Moreover, kittens were also nursed from queens fed diets containing either 0.58 or 12 micrograms Cu/g of diet. In each experiment, copper was analyzed in liver, spleen, lung, heart, muscle and brain samples. The liver copper concentration was the most responsive to changes in dietary copper intake. For example, in weanling kittens fed 0.58 or 9.8 micrograms Cu/g diet, the liver copper concentration was 24 or 45 micrograms/g wet weight, respectively. Likewise, the levels of hepatic Cu,Zn-superoxide dismutase were reduced in kittens fed the low copper diet. However, the concentrations of zinc, iron and manganese in liver, lung, spleen, brain, muscle and kidney were not consistently changed in response to low copper intakes. Anemia was also not a consistent feature in the copper-deficient cat or kitten, but signs of connective tissue lesions were observed in kittens born to and weaned from queens fed diets containing less than 1 micrograms Cu/g diet. Based on these observations and data for changes in growth in response to the differing levels of dietary copper, the copper requirement for the kitten was estimated to be 4-5 micrograms/g of diet (energy content approximately 5 kcal or 21 kJ per gram).