Effect of Phytase on Ileal Amino Acid Digestibility, Nitrogen Retention and AMEn for Broilers Fed Diets Containing Low and High Phytate Phosphorus
A 42 d broiler experiment was conducted to determine the effect of added Escherichia coli phytase (Phyzyme-XP 5000G) to low and high phytate P (PP) diets on performance and nutrient digestibility. The experiment consisted of 12 treatments with 2 levels of PP: Low-Phytate (LP) group-0.24% and High-Phytate (HP) group-0.32%. Both LP and HP groups had respective Positive Controls (PCs) with 0.39% in the starter and 0.29% NPP in the grower, respectively and 5 basal diets with graded levels (0, 250, 500, 750 and 1000 FTU's/kg diet) of added phytase.
The HP diets contained additional PP because canola and rice bran were substituted for part of the corn and soybean meal. GE retention was significantly improved 6% percentage points for 42 d broilers fed either LP or HP diets with added phytase however a significant interaction indicated the improvement in energy retention caused by phytase was primarily from the broilers fed the HP diet.
Overall there was no significant main effect of phytase on GE retention of 21 d broilers but the energy retention of HP diet was significantly less than for LP fed broilers and broilers fed the LP diet showed a significant improvement an interaction suggested the phytase would only benefit broilers fed the LP diet. The ileal % digestibility of threonine, tryptophan and serine were affected by PP levels, phytase and the interaction of PP and phytase for 21 d broilers, whereas cystine was the only amino acid to show all three main effects for 42 d broilers.
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