Phytase is added to pig diets to improve P digestibility but may also improve amino acid (AA) digestibility. Data from experiments evaluating the dose–response effect of a phytase are used to determine AA “matrix” values, i.e., the amount by which the diet may be reduced in AA due to the expected contribution of the phytase. In this study, data from 8 datasets generated from 5 experiments (325 data points) on the effect of a consensus bacterial 6-phytase variant (PhyG) on AA digestibility in growing pigs were combined and modeled by log-linear regression. The model predicted 3.7 and 4.5 percentage unit increases in the ileal digestibility of total AA with the phytase added to the diet at 1,000 and 4,000 FTU/kg, respectively (vs. a non-supplemented diet). The percentage unit improvements in the ileal digestibility of the total and all 18 individual AA (above that achieved by the unsupplemented diet) increased with increasing phytase dose in a log-linear manner. Improvements were greatest for Trp, Thr, Gly, and Cys. An example is presented of how the model may be used to generate an AA matrix for the phytase in different diet types. The results support the use of the phytase in grower pig diets for improving AA digestibility.

Read the full article in the Journal of Animal Science.