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

• We determined the efficiency of a Buttiauxella 6-phytase on nutrient digestibility in growing pigs.
• The results showed a linear or quadratic response on most of the AA digestibility.
• Ileal and total tract digestibility of Ca, P and other nutrients enhanced in a dose dependent manner.

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 = 25 kg) 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 2000 FTU/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 45 g/kg BW determined at the beginning of each experimental period. Each period lasted for 9 d with 5 d of adaptation to experimental diets followed by 2 d of faecal and 2 d 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 2000 FTU/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 2000 FTU/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 2000 FTU/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 2000 FTU/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.