Reduction of Excretory Phosphorus and Trace Minerals by Dietary Supplementation of Microbial Phytase in Broiler Chicks

An experiment was conducted to study the effect of microbial phytase on excretory phosphorus (P), copper (Cu), zinc (Zn) and manganese (Mn) in broiler chicks. Male broiler chicks with three replications of 10 chicks each were given free access to the experimental diet from 7 to 21 days of age. The basal diet consisted mainly of corn, soybean meal and defatted rice bran, and contained 0.60% total P, 0.30% non-phytate P, 0.90% calcium, 8.1mg Cu, 82.3mg Zn and 95.3mg Mn per kg of diet, and 0.1% chromium oxide as an indicator. To the basal diet, defluorinated phosphate (0.075 and 0.15% as non-phytate P) or microbial phytase (125, 250 and 500units/kg of diet) was added. The excreta of each replication were collected for the last three days of the experiment, and the retention ratio and excretion of total P, phytate P, Cu, Zn and Mn were calculated.The retention ratio of total P, Cu and Zn increased almost linearly with the increase of supplemented phytase. When 500units/kg phytase were added, total P excretion was reduced by 31%, and the excretion of Cu and Zn was also reduced by 7%, respectively, in comparison with the diet containing 0.45% non-phytate P. However, the excretion of Mn was not affected by the addition of phytase.