Objective: Determination the effects of phytasc supplementation in broiler diets.
design: Randomized complete blocks design.
Animals: Two hundred eighty broiler chickens. Procedure: The experimental diets were prepared based on NRC (1994) recommendations except for Prequirement. The diets, C, I P, 2P and 3P consist of 0,300,600 and 900 units of phytase activity per Kg of diet (FTU/Kg) respectively without of inorganic phosphorus supplementation. The ID, 2D and 3D diets have similar composition with control diet (C) except for 1, 2 and 3 g phosphorus pre Kg of diet from dicalcuim phosphate (DCP). Factors related to phosphorus nutrition were measured during the experiment. Statistical analysis: Analysis of variance. duncan’s multiple range test of means, Linear regression equations.
Results: Addition of phytase had significantly effects on feed
intake, body weight gain, tibia ash, tibia length, tibia phosphorus and phosphorus excretion (P<0.05). Phytase had no significant effects on feed conversion ratio, mortality and the cost of diet for
production of 1 Kg of live body weight (P>0.05). Phosphorus
equivalency were calculated as 700 FTU/Kg for body weight gain and 400 FTU/Kg for tibia ash equal to I g phosphorus from phosphate. Implications: The phytase enzyme is able to hydrolyze the phytate
molecule and convert it to a nuiritive form and destroy it’s negative
effects. Depend on acquired results. We can conclude that
supplementation of phytase in broiler commercial diets is applicable
and there is no need of inorganic phosphorus supplementation
to diets without additional cost, and it can prevent the phosphorus
loss in manure. The optimal level of phytase inclusion in broiler diets is 600 FTU/Kg diet based on the results of thisJ.fac.vet.Med.Univ.Tehran.57,3:75-79,2002