Determination and estimation of phosphorus availability in growing poultry and their historical development

Abstract

The variability of phosphorus (P) availability in poultry feeds is large, primarily caused by differences in the contents of phytate and intrinsic or exogenous phytase and by differences between non-phytate sources of P. Attempts to consider this variability in feed formulations has led to the development of different approaches to determine P availability. In the past seventy years, different response criteria and descriptive terms for available P have been used. In this review, response criteria that are often used will be described, including their development over time. Focus is be given to growing poultry and to quantitative approaches based on P retention and precaecal digestibility, relative bioavailability based on bone data, and in vitro solubility tests. In conclusion, precaecal digestibility and retention are the most appropriate criteria for evaluating P sources in poultry. The use of blood inorganic phosphorus (Pi) concentrations and performance data is discouraged for the purpose of evaluation. Bone response data can provide relative availability values for P sources. More research is needed to explore whether P retention data can be re-calculated from existing bone response data. Improvements in in vitro approaches for estimating P availability are suggested.

Keywords::

• phosphorus
• availability
• evaluation
• approaches
• history