Since pigs are unable to digest phytate, the main form of phosphorus in grains and oil seeds, a substantial amount is excreted in manure. Of course, phosphorus is a limiting nutrient for manure land application.
Because phosphorus is an essential element for pigs, highly available inorganic phosphorus is typically supplemented in the diet to meet the pig’s needs. Using phytase lowers the amount of supplemental phosphorus required in the pig’s diet. Phytase also reduces the amount of excreted phosphorus, thereby enhancing manure-application options.
The amount of phytase needed in a diet depends on the dietary ingredients and the product’s enzyme activity, according to a report in the Journal of Swine Health and Production. It’s important to note that differences in laboratory assays exist, as well as differences among commercial products. One phytase unit, or FTU, of one product may not be equivalent to 1 FTU of another. “The manufacturer’s recommendations should always be followed due to differences between products,” says Joel DeRouchey, Kansas State University swine nutritionist.
For accurate diet formulation, it’s important to obtain phytase enzyme activity information from the supplier. As the amount of phytase added to a diet increases, the phosphorus release from phytate also increases in a curvilinear fashion. This means that phosphorus release diminishes with each additional unit of phytase until additional dietary levels of phytase fail to result in a further response.
Improved phosphorus utilization and reduced inorganic phosphorus in the diet result in less phosphorus excretion from pigs. Phytase also can increase availability of other minerals such as calcium.
Proper storage conditions and frequent product rotation are important to preserve its efficacy. Products containing phytase should be stored only in cool, dark, dry areas. DeRouchey points out that phytase is sensitive to degradation when stored in premixes subject to high temperature and moisture conditions. “More frequent product turnover in summer is critical to maintain a high level of phytase activity,” he adds.