Wheat and barley increase phytate degradation and phosphorus digestibility in corn fed to pigs

•Phytases in wheat and barley are non-specific but also degrades corn phytate.•Phytate degradation was not additive in barley, wheat and corn soaked together.•Thus, phosphorus digestibility is non-additive when wheat, barley and corn are mixed.•Non-additivity has to be taken into account when mixing cereals different in phytase.•Non-additivity was seen both in in vitro and in digestibility studies with dry feeding.