Phytase enzymes with higher affinity (lower kM) for phytates with six or five associated P units had a higher ability to reduce the anti-nutritive effect of phytate even when releasing the same amount of P
Higher enzyme dose
In order to use phytase, which is aimed at reducing the anti-nutritive effect of phytate, it is necessary to exceed the release of P derived from the enzyme. Initially, higher doses of phytase would be considered equivalent to reducing the need for additional inorganic P in the diet in an attempt to further reduce food costs while maintaining animal productivity.
However, an alternative approach is to try to eliminate the anti-nutritive effects of phytase through higher enzyme doses, thereby increasing nutrient absorption and animal productivity.
One study administered high doses of phytase (12,500 FTU/kg) to broilers on a diet with adequate available P (0.25%) and observed an increase in productivity. The second study observed not only higher productivity, but also higher levels of liver carotenoids in birds given higher doses of phytase.
Several studies with higher phytase doses using diets with normal P levels have shown better performance in poultry, but this increase in productivity is always associated with increased P digestibility, even when the diets do not have high-low P levels. In all these studies, increased productivity at higher phytase doses was associated with increased dietary conversion factors.