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

Abstract Text: The current study evaluated the effect of different levels of a 6-phytase derived from Buttiauxella spp. 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 6 x 6 Latin square design to give 12 observations per treatment. The experimental diets consisted of 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 indigestible marker. Pigs were given their daily feed allowance at a rate of 4.5% of BW determined at the beginning of each experimental period. Each period lasted for 9 d with 5 d of adaptation to the assigned experimental diet followed by 2 d fecal and 2 d ileal digesta collections. Data were analyzed using the mixed model procedures of SAS. The final model had treatment as the main effect since pen and period effects were non-significant. Increasing levels of 6-phytase supplementation linearly increased apparent ileal digestibility (AID) of DM, CP and GE (P < 0.01). Compared with NC, AID of Ca and P respectively increased (P < 0.05) by 5.9, 11.7, 9.0 and 12.3% and 12.7, 46.6, 49.1 and 77.4% with 250, 500, 1000 and 2000 FTU/kg of phytase. Mean AID of dispensable and indispensable AA improved (P<0.05) by 2.5, 2.0 and 1.0% and 2.0, 1.3 and 1.2%, respectively, for diets containing 500, 1000 and 2000 FTU/kg of phytase. Mean standard ileal digestibility (SID) of dispensable and non dispensable AA improved (P < 0.05) by 1.7, 1.2 and 2.8% and 1.0, 0.2, and 3.4% respectively, for diets with 500, 1000 and 2000 FTU/kg of phytase. Apparent total tract digestibility (ATTD) of DM, CP, and GE responded linearly (P < 0.01) to increasing levels of phytase. The ATTD of Ca and P respectively increased (P < 0.05) by 18.2, 30.4, 24.5 and 33.8% and 46.8, 98.4, 99.7 and 124.3% for diets supplemented with 250, 500, 1000 and 2000 FTU/kg of the 6-phytase. In conclusion, supplementation with a 6-phytase from Buttiauxella spp. expressed in Trichoderma reesei significantly enhanced the AID and ATTP of Ca, P and other nutrients in pigs, in dose dependent manner.

Keywords: Amino acid, calcium, phosphorus, phytase, ileal digestibility, pig