RELEVANCE OF NATIVE AND MICROBIAL PHYTASE FOR PHOSPHORUS UTILIZATION IN PIGS

To study the relevance of native phytase for phosphorus digestibility and for the relation between P-digestibility and the effectiveness or supplements of microbial phytase a series of balance experiments with 5 pigs (40-70 kg LW) was designed. Diets based on cereals and soyabean meal were fed, including four treatments with untreated and phy tase inactivated cereals, accomplished by extrusion. Both diets were supple mented wt the microbial phytase ZY 98 (LOHMANN LTE) with a dose of 800 U/kg. Reduction of phytase activity decreased P-digestibiljty of the diets from 45 % to 18 %. Microbial phytase supplements increased P-dig estibillty in the untreated diet by 7 %-U to 52 % and in the diet with inactivated phytase from 18 % to 47 %. The results document the effec ts of native phytase activity on P-digestibility and show that the eff icacy of supplements of microbial phytase depends basicly on the amoun t of native phytase activity and correspondingly on P-digestibility.