The effects of supplementary bacterial phytase on dietary true metabiolisable energy, nutrient digestibility and endogenous losses in precision fed turkeys
Résumé
ABSTRACT 1. Forty BUT 9 female turkeys were used in a precision feeding assay to investigate the effect of dietary phytase on true metabolisable energy corrected for N retention (TMEn), true nutrient digestibility (TND), and the excretion of endogenous mucin, measured as sialic acid (SA). 2. Five treatments (control (C), C + 250 FTU (phytase units per kg feed), C +500 FTU, C +2500 FTU, and glucose only for endogenous losses estimation) were used in this study and each treatment was replicated eight times in a randomised complete block design. Diets were formulated to be nutritionally adequate with the exception that the P content was relatively low (3.6 g/kg non-phytate P). 3. Inclusion of phytase increased TND in a quadratic manner with the optimum being achieved at approximately 500 FTU, at which TND was 37.3% improved compared to the control. The concentration of SA in the excreta decreased linearly (P<0.05) with increased phytase supplementation. Dietary TMEn, true dry matter digestibility (TDMD) and true mineral digestibility coefficients were not affected (P>0.05) by phytase supplementation. 4. Phytase inclusion increased digestibility coefficients for indispensable, dispensable and total amino acids in a linear manner. The scale of the response to phytase was greatest with threonine least with lysine digestibility, suggesting a specific mechanism of action that benefits the gut health. 5. The strong negative relationship between secretion of SA and threonine digestibility suggests that a large part of the threonine benefit may be from reduced mucin synthesis. This supports the hypothesis that dietary phytase may play a role in improving the health status of the intestine and as a result reducing the maintenance energy requirements of turkeys.
Domaines
Biologie animale
Origine : Fichiers produits par l'(les) auteur(s)
Loading...