The effectiveness of an Escherichia coli phytase in improving phosphorus and calcium bioavailabilities in poultry and young pigs

The effectiveness of an Escherichia coli phytase in comparison with a comme rcially available Aspergillus phytase in improving the bioavailability of p hosphorus in broilers, layers and young pigs was studied in three separate experiments. Three basal diets, marginally deficient in dietary P mainly pr ovided as phytate, were formulated. Both phytases were added to the diets a t the rate of 500 U/kg diet. The phytases significantly (P less than or equ al to 0.05) improved the availability of phytate P to broilers, layers and young pigs. Aspergillus and E. coli phytases enhanced the pre-caecal digest ibility of P by 11 and 29% for broilers and 18 and 25% for layers, respecti vely. Total tract digestibility of P (P balance) was also enhanced but with smaller magnitude. In pigs, total tract digestibility of P was improved by 33 and 34% by Aspergillus and E. coli phytases, respectively. Under the co nditions of this study, it was observed that E. coli consistently, though w ith small magnitude in layers and pigs, enhanced the availability of phytat e P at the same range or slightly better than Aspergillus phytase. It was o nly in pigs that the availability of Ca was significantly (P less than or e qual to 0.05) improved by addition of both phytases. It can be concluded th at E. coli phytase is highly effective in improving the bioavailability of phytate P to broilers, layers and young pigs. This seems to be based on the high proteolytic stability of the enzyme in the digestive tract, as shown recently.