title: Zinc stores in chickens delay the onset of zinc deficiency symptoms.
abstract: Three chick assays were conducted to evaluate Zn depletion rates in whole body and various tissues. In Assay 1, chicks fed a corn-soybean meal diet containing 1,037 mg Zn/kg had twice as much Zn in intestine and bone and 50% more Zn in liver and whole body than chicks fed 37 mg Zn/kg (P < .01). In Assay 2, the minimum Zn requirement for growth of chicks consuming a chemically defined, amino acid diet was 10.6 mg Zn/kg. In Assay 3, chicks were fed the chemically defined diet containing either 300 or 10.6 mg Zn/kg during an 8-d pretest period, after which they were fed either 0 or 10.6 mg Zn/kg for 9 d. Tissue Zn concentrations were determined on Days 0, 1, 2, 3, 4, 5, 7, and 9 of the test period. Following the pretest period, Zn was higher in the liver, tibia, and small intestine, but not in muscle, of chicks fed 300 mg Zn/kg than of those fed 10.6 mg Zn/kg (P < .01). Growth of chicks switched from 10.6 to 0 mg Zn/kg was less than for chicks maintained on 10.6 mg Zn/kg by Day 5 (P < .05), whereas chicks switched from 300 to 0 mg Zn/kg did not display a growth depression relative to the control until Day 8 (P < .05). Zinc that accumulated in the liver and small intestine of chicks fed the 300 to 0 Zn regimen declined until Day 3 of the test period, whereas tibia Zn decreased until Day 8. Chicks fed the 10.6 to 0 regimen did not display a substantial decrease in small intestine, liver, or tibia Zn. The data confirm that Zn can accumulate in bone, liver, and intestine and can subsequently be released for use during a period of Zn deficiency. The data also indicate that chicks fed a diet containing the minimum requirement of Zn cannot accumulate reserves of Zn that become available for use during a subsequent period of Zn depletion.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Emmert
authors.forename: D H
authors.initials: DH
authors.lastname: Baker
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001835:Body Weight; D001842:Bone and Bones / Q000378:metabolism; D002645:Chickens / Q000254:growth & development*; D004032:Diet / Q000662:veterinary*; D007421:Intestine, Small / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009751:Nutritional Requirements; D009928:Organ Specificity; D014018:Tissue Distribution; D015430:Weight Gain; D015032:Zinc / Q000008:administration & dosage* / Q000172:deficiency / Q000378:metabolism*
chemical_list: D015032:Zinc