Hydrolysis of phytate and formation of inositol phosphate isomers without or with supplemented phytases in different segments of the digestive tract of broilers
- Publication Type
- Journal contribution (peer reviewed)
- Authors
- Zeller E, Schollenberger M, Kühn I, and Rodehutscord M
- Year of publication
- 2015
- Published in
- Journal of Nutritional Science
- Band/Volume
- 4 (e1)/
- DOI
- 10.1017/jns.2014.62
- Page (from - to)
- 12 p.
<p><span style="color: black; line-height: 107%; font-family: 'Arial',sans-serif; font-size: 12pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-themecolor: text1; mso-ansi-language: EN-GB; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">The objective was to characterise degradation of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) and formation of inositol phosphate (InsP) isomers in different segments of the broiler digestive tract. Influence of an Aspergillus niger (PhyA) and two Escherichia coli-derived (PhyE1 and PhyE2) phytases was also investigated. A total of 600 16-d-old broilers were allocated to forty floor pens (ten pens per treatment). Low-P (5·2 g/kg DM) maize–soyabean meal-based diets were fed without (basal diet; BD) or with a phytase added. On day 25, digesta from different digestive tract segments were pooled per segment on a pen-basis, freeze-dried and analysed for P, InsP isomers and the marker TiO2. InsP6 degradation until the lower ileum (74 %) in BD-fed birds showed a high potential of broilers and their gut microbiota to hydrolyse InsP6 in low-P diets. Different InsP patterns in different gut segments suggested the involvement of phosphatases of different origin. Supplemented phytases increased InsP6 hydrolysis in the crop (P < 0·01) but not in the lower ileum. Measurements in the crop and proventriculus/gizzard confirmed published in vitro degradation pathways of 3- and 6-phytasesfor the first time. In the intestinal segments, specifically formed InsP4–5 isomers of supplemented phytases were still present, indicating further activity of these enzymes. Myo-inositol tetrakisphosphate (InsP4) accumulation differed between PhyE1 and PhyE2 compared with PhyA in the anterior segments of the gut (P < 0·01). Thus, the hydrolytic cleavage of the first phosphate group is not the only limiting step in phytate degradation in broilers.</span></p>