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Greater bioavailability of chelated compared with inorganic zinc in broiler chicks in the presence or absence of elevated calcium and phosphorus

Authors Richards J, Fisher P, Evans J, Wedekind K

Received 3 March 2015

Accepted for publication 8 April 2015

Published 25 June 2015 Volume 2015:7 Pages 97—110


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Peter Koulen

James D Richards, Paula M Fisher, Joseph L Evans, Karen J Wedekind

Research and Development Department, Novus International Inc., Saint Charles, MO, USA

Abstract: Animal diets often contain antagonists that reduce Zn bioavailability, thereby creating a deficiency. The bioavailability of Zn chelated to 2-hydroxy-4-(methylthio)butanoic acid (chelated Zn) was compared with Zn sulfate in broiler chicks in two dietary conditions: a Zn-deficient corn-soybean meal (C-SBM) diet and a Zn-deficient C-SBM diet containing elevated Ca and P as antagonists. In experiment 1, chicks were fed a common diet (19 mg Zn/kg diet) through day 8, and then a Zn-unsupplemented (21 mg Zn/kg diet; 0.82% Ca, 0.47% available P) C-SBM basal or the basal supplemented with 5, 10, 15, 20, or 30 mg Zn/kg diet as chelated Zn or Zn sulfate for 6 days. Common-intercept, multiple linear regression slope-ratio analysis indicated significantly greater Zn bioavailability for chelated Zn relative to Zn sulfate as judged by: total tibia Zn (µg) (161%; P=0.001); tibia zinc concentration (µg/g; 165%, P=0.0009); and small intestinal metallothionein mRNA expression (248%; P=0.009). In experiment 2, chicks were fed a Zn-deficient (24 mg Zn/kg diet) common diet, then fed a C-SBM basal elevated in Ca and P (27 mg Zn/kg diet; 1.2% Ca, 1% available P), or the basal supplemented with 15 or 30 mg Zn/kg diet as Zn sulfate or 7.5, 15, or 30 mg Zn/kg diet as chelated Zn. Zn sulfate was antagonized to a greater extent than Zn chelate. Bioavailability of chelated Zn relative to Zn sulfate was 441% (P=0.0063; µg total tibia Zn), 307% (P=0.0066; µg/g tibia Zn), and 426% (P=0.0041; metallothionein). Thus, feeding chelated Zn offers advantages over inorganic Zn, especially in diets containing high levels of Ca and P, which is a common occurrence in pet food and in livestock diets.

Keywords: antagonism, broilers, chelate, metallothionein, minerals

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