Meta-analysis of Responses to Dietary Non-phytate Phosphorus and Phytase in Laying Hens

9 October 2012, at 12:00am

Analysing published data using diets based on maize and soybean meal, 0.22 per cent of of non-phytate phosphorus (NPP) without supplemental phytase resulted in good performance, according to researchers from Iran and Germany, while adding phytase to the feed meant that the dietary NPP level could be lowered.

Reducing the level of non-phytate phosphorus (NPP) in diets for laying hens without negatively affecting their productivity and health is crucial for sustainable egg production, according to a paper published recently in Poultry Science.

H. Ahmadi of Ferdowsi University of Mashhad in Iran and Professor M. Rodehutscord of the University of Hohenheim in Germany explain they applied a meta-analytical approach using a full quadratic model to quantify relationships between dietary NPP and phytase levels and performance of laying hens. Egg production (EP, %), egg mass (EM, g/hen/day) and feed conversion ratio (FCR) were considered as model outputs.

A data set containing 168 phosphorus or phosphorus-plus-phytase treatments was extracted from 12 published papers. The data were assembled from 14 trials with a total of 8,752 hens in the range of 36 to 76 weeks of age. Egg production, egg mass and feed conversion ratio were analysed using a linear mixed model that included the linear and quadratic effects of dietary NPP and phytase levels and their interactions.

Except for the quadratic effect of dietary phytase on FCR, all other model components (that is, intercept, linear, quadratic and interactions) were significant (P<0.05).

There were relatively strong relationships between observed and predicted egg production (R2=0.78, RMSE=3.73), egg mass (R2=0.84, RMSE=2.09) and feed conversion ratio (R2=0.78, RMSE=0.11), demonstrating that observations within study are practically predictable.

Analyses of the model revealed that corn-soybean meal-based diets containing 0.22 per cent of NPP without supplemental phytase resulted in high egg production, egg mass and feed efficiency in layers, concluded Ahmadi and Rodehutscord. In the presence of 150, 300 and 400 phytase units (FTU) per kg of feed, the dietary NPP level may be decreased and optimal levels were calculated as 0.18, 0.15, and 0.14 per cent, respectively.


Ahmadi H., and M. Rodehutscord. 2012. A meta-analysis of responses to dietary nonphytate phosphorus and phytase in laying hens. Poult. Sci., 91(8):2072-2078. doi: 10.3382/ps.2012-02193

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October 2012