In the present study, the other results of productive
performance, egg quality, serum and tibia had also
supported our hypothesis that FPP would release phytate-
bound phosphorus of corn-soybean layer diet. It
was reported that the lower phosphorus led to low ADFI
(Usayran et al. 2001; Keshavarz 2003; Augspurger et al.
2007), but the significant difference of ADFI was not
appeared when the DCP content of corn-soybean-FPP
diet was reduced to 0.67% in this research. Furthermore,
the eggshell hardness and eggshell thickness were not
reduced significantly until the DCP content of cornsoybean-
FPP diet was reduced to 0.34%. This result
agreed with the report of Gordon and Roland (1997):
the reduction of eggshell quality from the non-phytate
phosphorus was overcome when diets were supplemented
with phytase. It was reported that the phytase
added to the deficient phosphorus feed improved the
pigmentation of the egg yolk (Kozlowski and Jeroch
2011; Englmaierová et al. 2012). In the present study,
the yolk color improved significantly when the laying
hens were fed deficient DCP corn-soybean-FPP diet.
The reason of the yolk color improved was maybe the
effect of phytase of FPP on improving the pigmentation
of the egg yolk.