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Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801
A repletion-depletion assay was conducted to evaluate the effect of Mn status and excess dietary P provided as dicalcium phosphate on Mn excretion and turnover. Chicks were fed either Mn-adequate (30 mg Mn/kg) or high Mn (1000 mg Mn/kg) casein-dextrose diets for 7 d. Following this loading period, the chicks were fed a Mn-deficient casein-dextrose diet (1.4 mg Mn/kg) with or without 0.5% excess P supplied from dicalcium phosphate. Whole body (without feathers) and selected body tissues (liver, kidney, gut, tibia and feathers) were assayed for Mn content at 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 15 and 20 d after initiation of the Mn-deficient diet. Excess P had little effect on Mn turnover. All tissues showed significantly reduced biological half-lives (P < 0.05) as a result of loading chicks with a high level of Mn (1000 mg/kg) during the 7-d loading period. However, there was wide variation in Mn turnover rates among tissues. Liver, kidney and whole body contained readily exchangeable manganese in much higher proportions than did bone.
KEY WORDS: turnover manganese phosphorus chickens repletion-depletion
1 Part of a thesis presented by K. J. Wedekind to the Graduate College, University of Illinois, for partial fulfillment of requirements for the Ph.D. degree in Animal Sciences.
2 Present address: Department of Animal Sciences, University of Nebraska, Lincoln, NE 68583-0908.
3 To whom correspondence should be addressed: 328 Mumford Hall, 1301 West Gregory Drive, University of Illinois, Urbana, IL 61801.
Manuscript received 5 September 1990. Revision accepted 5 December 1990.