ORIGINAL ARTICLE Effects of ethylenediaminetetraacetic acid on phytate phosphorus utilization and efficiency of microbial phytase in broiler chicks Y. Ebrahimnezhad 1 , M. Shivazad 2 , R. Taherkhani 2 and K. Nazeradl 1 1 Department of Animal Science, College of Agriculture, Azad Islamic University, Shabestar, Iran, and 2 Department of Animal Science, Faculty of Agriculture, University of Tehran, Karaj, Iran Introduction The major ingredients used in poultry feeds are of plant origin. About two-third of the phosphorous (P) in these feedstuff is present as phytate P, which is poorly utilized by poultry. The inability of poultry to utilize phytate P causes both economic and environ- mental problems. Physical methods, such as soaking, drying, germination (Jongbloed et al., 1991), supple- mentation of diets with exogenous microbial phytase (MP) (Kornegey, 2001) and vitamin D (Mitchel and Edwards, 1996) have found to be effective in increasing phytate hydrolysis. Several authors (Bolling et al., 1998; Boling et al., 2000a; Boling- Frankenbach et al., 2001; Brenes et al., 2003) have found that citric acid alone or in combination with phytase increased the phytate hydrolysis in chicken. Theoretically, these supplements could have syner- gistic or additive effect. Interaction between MP and vitamin D analogues (Biehl et al., 1995; Mitchel and Edwards, 1996) and phytase and citric acid (Boling et al., 2000a,b) have been assessed, but little work has been done to determine if organic acids, other than citric, will improve phytate P utilization in Keywords EDTA, phytase, alkaline phosphatase, broiler Correspondence Reza Taherkhani, Department of Animal Science, Faculty of Agriculture, University of Tehran, Karaj, Iran. Tel/Fax: +98 261 22248082; E-mail: rtaher@ut.ac.ir Received: 6 February 2007; accepted: 2 April 2007 First published online: 18 July 2007 Summary Previous studies have suggested that organic acids may improve P util- ization in animals. To evaluate the ability of ethylenediaminetetraacetic acid (EDTA) to improve phytate P utilization and the possible synergistic effect between EDTA and microbial phytase (MP) an experiment was conducted using 360 Ross 308 broiler chicks. The experiment was car- ried out using a completely randomized design with a 3*2 factorial arrangement (0, 0.1 and 0.2% EDTA and 0 and 500 IU MP). Four repli- cate of 15 chicks per each were fed dietary treatments including (i) P-deficient basal diet [0.2% available phosphorus (aP)] (NC); (ii) NC + 500 IU MP per kilogram of diet; (iii) NC + 0.1% EDTA per kilo- gram of diet; (iv) NC + 0.1% EDTA and 500 IU MP per kilogram of diet; (v) NC + 0.2% EDTA per kilogram; and (vi) NC + 0.2% EDTA + 500 IU MP per kilogram of diet. Weight gain (WG), feed efficiency and serum Ca, P and alkaline phosphatase (ALP) were assessed. Addition of 0.2% EDTA to low aP diets resulted in significantly lower feed consumption (FC) and WG, but 0.1% EDTA did not depress WG compared to NC. Phytase supplementation of P-deficient diets significantly improved WG and feed efficiency, but it had no effect on FC. Microbial phytase sup- plementation significantly decreased ALP concentration. Results obtained in our study suggest no synergistic effect between phytase and EDTA in broiler chicks. DOI: 10.1111/j.1439-0396.2007.00722.x 168 Journal of Animal Physiology and Animal Nutrition 92 (2008) 168–172 ª 2007 The Authors. Journal compilation ª 2007 Blackwell Publishing Ltd