Effect Of Phytase Dose And Form On The Residual Rate Of Activity In Steam-pelleting

There were 2 experiments in this study.The experiment 1 was to investigate the effects of dietary phytase dosage and forms of coated phytase on the residual rate of phytase activity in the process of steam conditioning-pelleting-cooling.The dietary phytase dosage was supplemented as 5 levels of 7560 U/kg,14310 U/kg,33830 U/kg,43590 U/kg and 61500U/kg.Six forms of phytase contained 1 naked phytase(CP0),4 phytase(CP1,CP2,KP1,KP2)coated with naked phytase CP0 and marketed coated phytase MP.The results showed that the dietary phytase activity dosage didn’t significantly affect the residual rates of phytase activity after steam conditioning-pelleting-cooling(P>0.05).There was no significant interaction effect between the dietary phytase activity dosage and the conditioning temperature on the residual rates of phytase activity after conditioning-pelleting-cooling(P>0.05).Compared with the control(CP0),the 5 coated phytase did not significantly improve the phytase activity residual rates.When the temperature increased from 75℃ to 85℃,the residual rate of phytase MP was not significantly different,whereas,the residual rates of phytase activity of the remaining 5forms were significantly decreased(P<0.05).The experiment 2 was to investigate the difference of the activity residual rate of phytases with 10 forms collected from market.The experiment was designed as a split-plot,with 10 phytase forms assigned to the main plots and conditioning temperature of 75℃ or85℃ assigned to split-plots.There were 4 replicates for each treatment.The results showed that the residual rates of phytase activity after conditioning-pelleting-cooling were significantly affected by the phytase forms(P<0.05).Relatively greater activity residual rates were observed in phytases 2,5,8 and 10.Median activity residual rates were observed in phytases 1,4 and 9.Whereas,relatively less activity residual rates were observed in phytases 3,6 and 7.When the conditioning temperature increased from 75℃ to 85 ℃,the residual rates of phytase activity after conditioning-pelleting-cooling were decreased significantly(P<0.05).