299 Effect of the inclusion of Axtra® Pro on the ileal and total tract digestibility of energy and nutrients, concentrations of metabolizable energy, and N retention in a commercial diet fed to swine.

Abstract Two experiments were conducted to determine the effect of the inclusion of Axtra® Pro on the ileal and total tract digestibility of energy and nutrients in diets fed to growing pigs. For Exp. 1, a corn, soybean meal, DDGS, and wheat middlings-based diet was formulated. Dietary treatments consisted of a control diet, and the control plus Axtra® Pro added to achieve 4,000, 8,000, and 12,000 U/kg of feed. A total of 12 barrows (DNA 200 x 400, BW: 36.1±1.62kg) were allotted to a triplicated 4x4 balanced complete Latin square design with 4 treatments and 4 experiment periods. All animals were individually housed in metabolic crates equipped with a drinker, a feeder, and a partial diamond-slatted floor. For each experimental period, the first 5-d were considered adaptation, and the next 5-d were considered collection, for which a screen and a urine pan were installed to allow for the total and separate collection of feces and urine. There was a 7-d washout period after every experimental period before new dietary treatment was provided to the animals. For Exp. 2, three diets similar to Exp. 1 containing 0, 4,000, and 8,000 U/Kg of Axtra® Pro were formulated with titanium dioxide as an undigestible marker. A N-free diet was also formulated for a total of 4 dietary treatments. Twelve surgically cannulated barrows (DNA 200 x 400, DNA; BW: 32.6±1.81 kg) were used for a total of 5 periods of 7 days each, consisting of 5 days of adaptation and 2 days of collection, with a 7-d washout period between experiment periods. On each collection day, ileal samples were collected for 8h. Pigs were housed individually in pens equipped with a drinker, feeder, and smooth side walls. For Exp. 1, no differences were observed in the concentrations of DE and ME, ATTD of GE, DM, Ca, P, ADF, OM, and fat, and N retention. However, a quadratic effect (P < 0.05) was observed for the ATTD of DM, NDF, and OM. For Exp. 2, no differences were observed in the AID of DM and AEE. However, a quadratic effect (P < 0.05) of the inclusion of Axtra® Pro was observed for the AID and SID of CP and most AA, except for Leu and Ala, where the greatest values of digestibility were observed at 4,000 U/kg but decreased at 8,000 U/kg of feed. In conclusion, the ATTD of most nutrients was unaffected by the inclusion of Axtra® Pro under the conditions of this study. However, the ATTD of NDF and SID of CP and AA increased by including 4,000 U/kg of Axtra® Pro.