Efficacy of novel 6-phytase from Buttiauxella sp. on ileal and total tract nutrient digestibility in growing pigs fed a corn-soy based diet

The current study evaluated the effect of different levels of a 6-phytase from Buttiauxella sp. expressed in Trichoderma reesei on ileal and total tract nutrient digestibility in growing pigs. Twelve ileal cannulated pigs (initial BW=25kg) were randomly assigned to 1 of 6 treatments in a replicated 6×6 Latin square design to give 12 observations per treatment. The experimental diets consisted of a corn soybean meal-based control diet (NC), NC supplemented with 4 levels of phytase (i.e. 250, 500, 1000 and 2000FTU/kg) and a low-protein diet (5% casein) used to quantify endogenous amino acid (AA) losses. All diets contained titanium dioxide as an indigestible marker. Pigs were given their daily feed allowance at a rate of 45g/kg BW determined at the beginning of each experimental period. Each period lasted for 9d with 5d of adaptation to experimental diets followed by 2d of faecal and 2d of ileal digesta collection. Data were analyzed using the mixed model procedures of SAS. The final model had treatment as the main effect as pen and period effects were non-significant. Increasing levels of 6-phytase supplementation linearly increased (P<0.05) apparent ileal digestibility (AID) of dry matter (DM), crude protein (CP) and gross energy GE. Compared with NC, AID of phosphorus (P) increased (P<0.05) by 12.7, 46.6, 49.1 and 77.4% with 250, 500, 1000 and 2000FTU/kg of phytase, respectively along with AID of calcium (Ca) showing a tendency for improvement. Mean AID of indispensable and dispensable AA improved (P<0.05) by 2.3, 2.0 and 1.1% and 2.1, 1.2 and 1.2% for diets containing 500, 1000 and 2000FTU/kg of phytase, respectively. Mean standard ileal digestibility (SID) of indispensable and dispensable AA improved (P<0.05) by 1.7, 1.2 and 2.8% and 1.0, 0.2, and 3.6% for diets with 500, 1000 and 2000FTU/kg of phytase, respectively. Apparent total tract digestibility (ATTD) of DM, CP and GE responded linearly (P<0.05) to increasing levels of phytase. The ATTD of Ca and P increased (P<0.05) by 18.2, 30.4, 24.5 and 33.8% and 46.8, 98.4, 99.7 and 125.3% for diets supplemented with 250, 500, 1000 and 2000FTU/kg of the 6-phytase, respectively. In conclusion, the supplementation of diets with a Buttiauxella 6-phytase significantly enhanced the AID and ATTD of Ca, P and other nutrients in pigs, in a dose dependent manner.