Simultaneous application of phytase and xylanase to broiler feeds based on wheat: feeding experiment with growing broilers

In a 2 week study with broilers, graded levels of phytase added to feeds containing 6.70 g kg−1 of Ca, 4.80 g kg−1 of total phosphorus along with the recommended xylanase dosage (400 FXU kg−1) improved body weight gains quadratically (R2 = 0.55; p < 0.0001). Xylanase supplementation to feeds containing 0, 600 or 1000 units kg−1 of phytase significantly improved gains (p = 0.0072) and decreased viscosities of intestinal contents (p < 0.0001). High phytase concentrations in feeds (1000 FTU kg−1) increased intestinal viscosities, whereas, in the presence of xylanase, graded levels of phytase linearly reduced viscosities below the levels attained with xylanase fed as a sole supplemental enzyme (p = 0.033). Contents of ash in the toes were increased by phytase supplementation (p = 0.0011), the effect being more pronounced in birds consuming feeds that also contained xylanase. Improvements in performance and in bone mineralisation resulting from phytase and xylanase supplementation were lower than those observed in the control diets containing 4.50 g kg−1 of available phosphorus. The in vitro dialysable phosphorus predicted 71% of the variability observed in body gains, whereas amounts of pentoses freed from feed samples in vitro were highly correlated (R = 0.919) with feed efficiencies when the data were subjected to Hanes transformation. © 1999 Society of Chemical Industry