Calcium is a special mineral in terms of phytate and phytase. It has the lowest binding affinity for phytate, but is present in the largest amount in feed for poultry. Therefore, lowering the amount of phytate bound phosphorous with phytase potentially expands the ratio of calcium to total phosphorous to 2:1. Phytate decreases the utilization, usability and absorption of both calcium and phosphorous. Recommendations are usually to reduce the volume of calcium to minimize potential problems associated with its effects on the availability of phytate to phytase. However, in practice it is not uncommon to observe little or no change was in calcium, when phosphorus is dropped. This is especially true in laying birds, where changes in the amount of calcium is closely followed by the manufacturers to not jeopardize the quality of the shell.
From the three types of phytases available on the U.S. market, only one supplier posted matrix values for nutrients besides calcium and phosphorus for the species. As our understanding of the origin of the effects of phytate and the level and dynamics of their interactions with intestinal phytases develops, nutritionists will determine the matrix values for amino acids and energy with higher accuracy. In the future, under certain conditions, it may even be appropriate to use phytases alongside with the amount of phytate in the mixture, instead of just removing the predetermined amount of inorganic phosphorus. Since phytate is associated with fibers in the cell wall (NSP) of some components, phytase enzymes can provide further benefits for the NSP components of the feed.
Least but not last - the use of grains with low amounts phytic acid (phytate) may reduce the potential capture of nutrients, simply due to the presence of less phytate and hence lower potential of the substrate to connect other nutrients. However, these improved crops still contain phytate and would react to the addition of phytase.