Exogenous phytase and xylanase exhibit opposing effects on real-time gizzard pH in broiler chickens |
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| Authors: | S A Lee J Dunne E Febery C A Brearley T Mottram M R Bedford |
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| Institution: | 1. AB Vista, Marlborough, Wiltshire, UKSophie.Lee@abvista.com;3. Drayton Animal Health, Stratford-Upon-Avon, Warwickshire, UK;4. School of Biological Sciences, University of East Anglia, Norwich, UK;5. eCow Devon Ltd., Exeter, Devon, UK |
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| Abstract: | ABSTRACT1. The current study was conducted to evaluate the influence of high phytase doses and xylanase, individually and in combination, on performance, blood inositol and real-time gastric pH in broilers fed wheat-based diets.2. In a 42-d experiment, a total of 576 male Ross 308 broiler chicks were allocated to 4 dietary treatments. Treatments consisted of a 2 × 2 factorial arrangement, with 500 or 2500 FTU/kg phytase and 0 or 16 000 BXU/kg xylanase, fed in two phases (starter 0–21; grower 21–42 d). Heidelberg pH capsules were administered to 8 birds from each treatment group, pre- and post-diet phase change, with readings captured over a 5.5-h period.3. At 21 and 42 d, birds fed 500 FTU/kg phytase without xylanase had on average 127 and 223 g lower weight gain than all other treatments, respectively (P < 0.05). At 42 d, body weight-corrected feed conversion ratio (bwcFCR) was reduced (P < 0.05) by supplementing 2500 FTU/kg phytase or xylanase, with the combination giving a 12 point reduction in bwcFCR compared to birds fed 500 FTU/kg phytase without xylanase. Inositol content of plasma was twice that of the erythrocyte (P < 0.001), with 2500 FTU/kg phytase tending to increase (P = 0.07) inositol content in both blood fractions.4. Across all treatments, capsule readings ranged from pH 0.54 to 4.84 in the gizzard of broilers. Addition of 2500 FTU/kg phytase to the grower diet reduced (P < 0.05) average gizzard pH from 2.89 to 1.69, whilst feeding xylanase increased (P < 0.001) gizzard pH from 2.04 to 2.40. In contrast, digital probe measurements showed no effect of xylanase on gizzard pH, while addition of 2500 FTU/kg phytase increased (P = 0.05) pH compared to 500 FTU/kg phytase with or without xylanase.5. These findings suggested that xylanase and high phytase doses have opposite effects on real-time gastric pH, while similarly improving performance of broilers. |
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| Keywords: | Capsule gizzard pH phytase xylanase |
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