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Modeling digestibility of dietary phosphorus in growing and finish pigs

Lookup NU author(s): Vasilis Symeou, Emerita Professor Sandra Edwards, Professor Ilias Kyriazakis


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Low P digestibility combined with intensive pig production can lead to water pollution. The aim of this paper was to develop a model able to represent P digestion in pigs across diets and contribute towards the reduction of P excretion. Phosphorus in plant feedstuffs includes some nonphytate P (NPP) that is readily digested but is mostly as organic phytate P (oP) that is indigestible unless it is dephosphorylated. The ability of pigs to dephosphorylate oP using endogenous phytase enzymes is limited and is a function of Ca intake. The effect of Ca (g/kg diet) on the proportion of oP dephosphorylated (kg/kg) in the small intestine (SI) and large intestine (LI) was determined as 0.26 - (0.015 × dietary Ca) and 0.69 - (0.059 × dietary Ca), respectively. The dephosphorylated oP in the LI was assumed to be indigestible and was excreted. Proportion of oP dephosphosphorylation (kg/kg) by microbial and plant phytase activity (FTU) in the stomach was estimated to be 0.56 × [1 - exp(-0.001 × FTU)] and 0.38 × [1 - exp(-0.002 × FTU)], respectively. Phosphorus digestibility (kg/kg) of NPP and dephosphorylated oP in the SI was assumed to be constant at 0.8. The model was used to predict P digestibility in 2 experiments by Stein et al. (2011) and Poulsen et al. (2010) and compare the predictions with experimental outcomes. The model successfully predicted the P digestibility to a range of dietary Ca concentrations and for 2 levels of supplementation with microbial phytase. However, the predictions overestimated P digestion systematically but always within a 10% margin of the observed values. The model could be a useful tool for formulating strategies to improve the efficiency of P digestion and reduce soluble P excretion in pigs.

Publication metadata

Author(s): Symeou V, Edwards SA, Kyriazakis I

Publication type: Article

Publication status: Published

Journal: Journal of Animal Science

Year: 2012

Volume: 90

Issue: suppl. 4

Pages: 59-61

Print publication date: 01/12/2012

ISSN (print): 0021-8812

ISSN (electronic): 1525-3163

Publisher: American Society of Animal Science


DOI: 10.2527/jas.53804

PubMed id: 23365282


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