To estimate P equivalency of each enzyme combination,
a quadratic equation was derived from dietary
nPP (%) concentration and tibia ash (%) using a nonlinear
regression model: Y = aX2+ bX + c, in which
Y = the tibia ash as a percentage, and X = dietary
nPP level (%) using data collected in a factorial experiment.
Then this equation was solved using the tibia ash
(%) data collected to calculate X values or inorganic P
equivalency values of each of the treatments. To obtain
the P equivalency of each enzyme and its combination,
0.15 (% of nPP level of basal diet) was subtracted from