The objectives of this study were to determine the effects of microbial phytase supplementation over a range of Non-Phytate Phosphorus (NPP) on some serum parameters of broiler chickens fed corn-soybean meal diets. The experimental diets were as follows: diet 1) 0.31% NPP during starter and 0.29% NPP during grower and finishing periods without phytase; diet 2) 0.31% NPP during starter and 0.29% NPP during grower and finishing periods plus phytase (a commercially available microbial phytase preparation, Natuphos 1000 was added at 500 phytase units kg-1 diet); diet 3) 0.38% NPP during starter and 0.36% NPP without phytase; diet 4) 0.38% NPP during starter and 0.36% NPP during grower and finishing periods plus phytase; diet 5) 0.45% NPP during starter and 0.43% NPP during grower and finishing periods without phytase; diet 6) 0.45% NPP during starter and 0.43% NPP during grower and finishing periods plus phytase. At 21 and 42 day of age, Serum Ca, P, Mg, Albumin and total protein were measured. The results have showed that supplementation broiler diets with commercial phytase increased levels of NPP, P, Albumin and total protein concentrations and decreased serum Mg however, Ca concentration did not change.
