Fecal Excretion, Tissue Accumulation and Turn-Over of 54Manganese after Intravenous Dosing in Holstein Calves Fed a Practical-Type Diet2

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Abstract
Nine, male Holstein calves, fed a practical-type diet with 31 ppm manganese, were sacrificed 1, 5, or 21 days after a single tracer 54Mn dose was administered intravenously to study manganese metabolism. The results were compared with 65Zn data from earlier studies. Feces were the predominant way of endogenous 54Mn excretion, with 40% excreted within 2 days and 73% in 21 days. Endogenous fecal 54Mn excretion rate was far faster than that of 65Zn. One day after dosing, highest 54Mn levels were in pancreas, liver, kidney, gall bladder, bile and spleen. The fastest decline was in bile, liver, spleen and most gastrointestinal tract tissues, with the slowest rates in bone, muscle, skin, heart and testicles. The 54Mn turnover rate was much more rapid than 65Zn, but there is a similar relative order of rates among the various tissues. Whole blood 54Mn declined rapidly through 24 hr. after dosing, was approximately level to day 5 and then increased to day 14. The data indicate that much more rapid endogenous excretion, combined with considerably less transport from the small intestine to other tissue, as shown previously, are important ways by which the body keeps manganese concentrations much lower than zinc even though dietary intake is similar or greater. Copyright © 1973. American Society of Animal Science . Copyright 1973 by American Society of Animal Science.

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