Introduction to phytase
The primary constituents of diets for pigs are plant-based ingredients
which come primarily from the seeds of plants. The major fraction of the stored phosphorus
in plants is found in seeds mainly as a component of the molecule phytin.
Phytin-phosphorus is poorly available to pigs, and this availability varies both within and among ingredients.
The enzyme phytase releases phosphate groups from phytin making
the released phosphorus potentially available to the animal. Phytase is the only recognized
enzyme that can initiate the release of phosphate from phytin. The commercially available phytases are either 3-phytases or 6-phytases. These two types of phytase are characterised according to where they cleave the phytic acid molecule.
Phytases are also distinguished by the microbiological origin. It is sometimes claimed that the microbiological origin contributes to specifically positive characteristics.
The market for phytases was for quite many years dominated by the products from BASF and Novozymes but within the last five years several competitors have launched their own phytases.
There are several essential parameters to note in the choice of phytase. Here the most important ones are listed:
- How much phytase activity do I get for my money and how much activity is needed to release the required amount of phosphorus?
- Heat stability; the product must be able to tolerate high temperatures during pelleting
- At which pH level is the phytase most efficient? Most of the phosphorus released from phytic acid takes place in the stomach so the phytase must be most efficient at the pH levels present in the stomach.
- How fast does the phytase release phosphorus in the stomach? Retention time of the digesta in the stomach is limited and therefore crucial for the efficacy of the phytase.