Are all phytases the same?
Let us talk about the different phytases and their origin. First, phytase brands - Natuphos, Ronozyme P, both derived from different types of mushrooms (respectively Aspergillus niger vs. A. ficuum). In contract, the newest phytase VemoZyme F NTP was obtained from Escherichia coli (bacteria) and has shown its positive effect on productivity, bone mineralization and phosphorus utilization in non-ruminants. Other phytases originating from E.coli have been developed as well, however they are not yet approved and available in the U.S.
Importance of pH
In the gastrointestinal tract phytases are "soluble" only at low pH, where they are mixed with the aqueous phase of the intestinal contents. Exactly at this point, phytase and phytate phosphorus from the feed can meet each other. At around pH 4 phytate starts form insoluble precipitates with cations (eg. calcium, zinc, iron and copper). At pH 6 insoluble phytate complexes are prevailing. In birds, ultimate solubility of phytate occurs in the glandular stomach and the gizzard (stomach area). After movements of the gastric contents to the duodenum and later to the small intestine, the pH begins to rise. There, excretion of phosphorus is the best and it is being utilized by the animals. At the end of the small intestine you can find the remaining insoluble phytate.
All phytases can seal off phosphorus from the phytate molecules under suitable conditions. Commercial forms of phytases have been said to be active in practically the same levels. However, you should know that the commercial phytases have different biochemical indicators are not necessarily identical. In general, the effects of different phytases in non-ruminants is influenced by biochemical factors such as pH profile, specific activity and resistance to the attacks of endogenous proteases.
Thermostability of the enzyme is an important feature, and it shows if it must be added after pelleting the feed or can be used as a direct additive to feed. This does not affect the activity of the enzyme "in vivo", when it is properly included in the feed.