Influence of Zinc Deficiency on Zinc and Dry Matter Content of Ruminant Tissues and on Excretion of Zinc

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Abstract
Inexperiments involving 24 animals, zinc and dry matter contents of various tissues were studied in zine-deficient and control goats and calves at various time intervals after control animals were fed the zinc-deficient diet. All samples were obtained before any symptoms of a deficiency occurred in the controls. Length of time, from 9 to 35 days, which controls were fed the deficient diet did not affect zinc content of tissues. Zinc content of hair, blood, liver, lung, kidney, femur, skin, and testicles was reduced in zinc-deficient animals. Zinc level was unaffected in brain and muscle tissues. In most tissues there was considerable overlapping between zinc content of controls and deficient animals, so that differences due to the deficiency are a statistical phenomenon rather than one of important value for diagnostic purposes with individual animals. Zinc content of hair may have some potential as a diagnostic aid. Dry matter content of tissues was affected relatively little by zinc deficiency or by species. Zinc excretion via feces was decidedly lower in zinc-deficient animals, but urinary excretion tended to be higher than for controls. Thus, fecal excretion is an important route of homeostatic conservation of zinc in deficient animals, but urinary excretion does not contribute to this conservation.