| Two experiments were conducted to examine the interaction between nutrient andphytase in the broiler diet by investigating the effects of phytase supplementation ongrowth performance,nutrient utilization and tibial mineralization,which will provide datawith right supplementation of phytase in the broiler diet.Exp.1 Effects of Levels of Energy and Available Phosphorus and TheirInteraction in the Broiler Diets on Efficacy of PhytaseA trial of 2×2×2 factorial design was conducted to evaluate the effects of phytase atthe level of 0, 500FTU/kg added in the broiler diets with different ME levels(11.90,11.70MJ/kg) and different AP levels(0.35%, 0.25%) on growth performance,nutrientutilization and tibial mineralization.A total of 640 AA broilers at 1-d age were allotted into8 treatments with 8 replicates of 10 birds each. The experiment was divided into 2periods(0-3w,4-6w) which lasted 7 weeks. The results indicated that:(1) In diets with phytase supplementation, ADFI of first period was decreased by2.52% (p＜0.05 ) and F/G of whole period was decreased by 1.81% (p＜0.05); utilizationsof DM,CP,Ca and P were improved by 0.97% (p＜0.10) ,1.49%(p＜0.20), 8.55% (p＜0.01) ,8.61% (p＜0.01 ) respectively; apparent ileal utilizations of EAA,NEAA,TAA(p＜0.20), TIr,Gly,Ala,Val (p＜0.10 ) and Ile(p＜0.05 ) were improved;the contents of tibialash(p＜0.05) in first period,tibial Ca(p＜0.05) and P(p＜0.01 ) in last period were alldecreased.But phytase didn't exhibit significant influence on ADG and energy utilization(p＞0.05).(2) Phytase and levels of energy,AP in diet didn't have significant interaction (p＞0.05) on broiler growth performance;phytase and energy had significant interaction (p＜0.01) on utilizations of DM,GE,P, contents of tibial Ca,P in first period and tibial Ca in lastperiod.utilizations of DM,GE in control treatment added phytase were higher significantly(p＜0.01) than low-energy treatment,the digestibility of P; contents of tibial Ca of twoperiods in low-enery treatment added phytase were higher significantly (p＜0.01 ),but thecontent of tibial P in first period was lower significantly (p＜0.01) than low-enerytreatment. Conclusion:Phytase added in diets affects broiler growth performance,nutrient utilization and tibialmineralization.In the point of growth performance, Supplementation of phytase in low-P,low-energy or low-P-energy diet can get the similar growth performance with the controltreatment.Exp.2 Effects of Levels of Energy in the Broiler Diets on Efficacy ofPhytase 324 AA broilers at 1-d age were used to investigate the effects ofphytase at the levelof 0,500FTU/kg added in the diets with three ME levels of 12.33, 12.13, 12.03 MJ/kg ongrowth performance and nutrient utilization. The chicks were allocated to 6 treatments,each of which had 6 pens of 9 chicks per pen. The results showed as followed:(1) Phytase supplementation significantly improved ADG, ADFI, FCR, utilizations ofDM, CP, Ca, P (p＜0.05 or p＜0.01), but had no significant effect on energyutilization(P＞0.05).(2) The diet with low energy level significantly decreased utilizations of DM, GE, Ca,P (p＜0.05 or p＜0.01), but had no significant effect on CP utilization and growthperformance (P＞0.05).(3) Phytase and energy had significant interaction (p＜0.05) on FCR, utilizations ofDM and Ca; improvements of growth performance and nutrient utilization by phytasesupplementation were greatest in middle-energy diet.Conclusion: Phytase added in broiler diets significantly improved growthperformance and nutrient utilization.In this experimental condition,the diet with energy12.13 MJ/kg added phytase at the level of 500 FTU/kg can gain optimal productiveefficiency.
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