title: Bioavailability of iron in cottonseed meal, ferric sulfate, and two ferrous sulfate by-products of the galvanizing industry.
abstract: Iron depletion-repletion assays were carried out with young chicks to establish Fe bioavailability values for Fe2(SO4)3.7H2O (22.7% Fe), Fe-ZnSO4.H2O (20.2% Fe, 13.0% Zn), Zn-FeSO4.H2O (20.2% Zn, 14.2% Fe), and cottonseed meal (200 mg Fe/kg). Standard hemoglobin response curves were established using feed-grade FeSO4.H2O (28.8% Fe) or reagent-grade FeSO4.7H2O (20.1% Fe) as standards such that relative bioavailability (RBV) could be assessed for the experimental sources of Fe. Weight gain, hemoglobin, and hematocrit responded linearly (P < 0.05) to Fe supplementation in all assays. Using hemoglobin as the response criterion, slope-ratio calculations established Fe RBV values of 126% for Fe-ZnSO4.H2O and 93% for Zn-FeSO4.H2O. The 126% value for Fe-ZnSO4.H2O was greater (P < 0.05) than the FeSO4.H2O standard (100%), but the 93% value for Zn-FeSO4.H2O was not different (P > 0.10) from the standard. However, evaluation of all criteria of response (hemoglobin, hematocrit, weight gain) suggested that neither Fe-ZnSO4.H2O nor Zn-FeSO4.H2O had different Fe RBV values than FeSO4.H2O. Standard-curve calculations were used for assessment of Fe RBV in Fe2(SO4)3.7H2O and cottonseed meal, as only a single level of Fe addition was studied for each of these products. Iron RBV in Fe2(SO4)3.7H2O was estimated to be 37%, whereas Fe RBV in cottonseed meal was found to be 56%. Both of these values were lower (P < 0.05) than the FeSO4 standard. The data suggest that the two new products, representing combinations of FeSO4.H2O and ZnSO4.H2O by-products of the galvanizing industry, are excellent sources of bioavailable Fe, whereas ferric sulfate and cottonseed meal are relatively poor sources of usable Fe.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
authors.forename: S D
authors.initials: SD
authors.lastname: Boling
authors.forename: H M
authors.initials: HM
authors.lastname: Edwards
authors.forename: J L
authors.initials: JL
authors.lastname: Emmert
authors.forename: R R
authors.initials: RR
authors.lastname: Biehl
authors.forename: D H
authors.initials: DH
authors.lastname: Baker
mesh_terms: D000821:Animal Feed; D000818:Animals; D001682:Biological Availability; D002645:Chickens; D003369:Cottonseed Oil; D019587:Dietary Supplements; D005260:Female; D005290:Ferric Compounds; D005296:Ferrous Compounds; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D007221:Industry; D007501:Iron / Q000493:pharmacokinetics*; D008297:Male; D013232:Steel; D015430:Weight Gain
chemical_list: D003369:Cottonseed Oil; D005290:Ferric Compounds; D005296:Ferrous Compounds; D006454:Hemoglobins; D013232:Steel; C020748:ferrous sulfate; C024823:ferric sulfate; D007501:Iron