Study Of Different Sources Phytase On Effects Of Laying Hens Fed Corn-miscellaneous Meal Diets

One thousand three hundred and twenty Hy-Line brown laying hens aged24weeks wereselected and randomly allocated into11treatments with8replicates of15birds. The dietarytreatments included control (0.36%nonphytate P in the diet), negative control (0.16%nonphytate P in the diet, NC), Phytase A treatment groups {NC+Phytase A(125u/kg,250u/kg,500u/kg, respectively),A125, A250, A500},Phytase B treatment groups{NC+Phytase B (125u/kg,250u/kg,500u/kg respectively), B125, B250, B500}.Phytase Ctreatment groups {NC+Phytase C (125u/kg,250u/kg,500u/kg respectively),C125,C250,C500}.This experiment was conducted to study the effects of the different sources phytase （Aderived from Pichia pastoris,B derived from Trichoderma reesei,C derived from Escherichiacoli）when adding at different levels in low phosphorus miscellaneous-meal diets on layingperformance, egg quality(eggshell strength,albumen height, haugh unit,yolk color),metabolism of calcium and phosphorus(plasma,tibia,calcium and phosphorus apparentdigestibility) and duodenum configuration, to determine optimal phytase and level in layinghens fed miscellaneous-meal diets.Exp1Effects of different sources phytase on laying performance and egg quality inlaying hens fed corn-miscellaneous meal diets.There were no effects of phytase on FCR and egg qulity(P>0.05). Hen-day eggproduction and feed intake were lower(P<0.05) for the NC,A125and C125compared withthe PC at24wk,but other groups had no effects (P>0.05).There were no effects of phytase onegg mass before4wk(P>0.05),while differences of egg mass were gradually manifested after5wk.Egg mass were lower(P<0.05) for the NC and B500compared with the PC at24wk.Exp2Effects of different sources phytase on metabolism of calcium and phosphorus andduodenum configuration in laying hens fed corn-miscellaneous meal diets.Hen tibia calcium and plasma calcium levels were not affected by the dietary treatments.At12wk,the plasma phosphorus level was lower(P<0.05) for NC and B500groups comparedwith the PC.What’s more,the plasma phosphorus level was lower(P<0.05) forNC,A125,B500and C125groups compared with the PC at24wk.The tibia strength for NCtreatment increased significantly(P<0.05) compared with A500and C500treatments,but hadno significant(P>0.05) difference with PC treatment.Low phosphorus diets decreased(P<0.05) the tibia ash compared with A500,B125and C500treatmens.While the apparent digestibilityof crude protein, calcium and phosphorus was lower (P<0.05) for NC and B500groupscompared with the PC, the other groups had no significant(P>0.05) difference with PCtreatment. Each treatment groups had no significant(P>0.05) difference about the villus heightof duodenal but the NC group had the shortest duodenal villus height.The crypt depth wasdeeper(P<0.05) for NC, A125and C125compared with the PC and the VCR waslower(P<0.05) for NC, A125and C125compared with the PC. Additionally,the VCR ofphytase B treatment was the best among the three phytase.In conclusion,it would increase egg production,egg mass and hen-day feed intake andimprove the apparent digestibility of crude protein, calcium and phosphorus and duodenumconfiguration when low phosphorus miscellaneous-meal diets supplemented withphyase.While the effects of three phytase were similar, the optimal dose of three phytase wasdifferent. The optimal dose of phytase A and C was250U/kg,but phytase B was125U/kg.What’s more, excessive addition of phytase B would decrease performance of layinghens.