The impact of xylanase and body weight, and their interaction, on the utilization of dietary components in swine
The increased use of corn co-products in swine diets has prompted interest in the ability of carbohydrase enzymes, such as xylanase, to assist the pig in fiber degradation. It has been proposed that, by breaking down arabinoxylans, xylanase enzymes can mitigate the negative effects of fiber on digestive efficiency. However, previous studies with xylanase in corn-based diets in swine have produced inconsistent results. A digestibility study was conducted in order to better understand how the enzyme impacts diet utilization in the pig by measuring the impact of xylanase on energy and nutrient digestibility in the small and large intestines and across the total tract. Thirty-two gilts (32.6 Ã Â Ã Â± 0.47) were surgically fit with T-cannulae at the terminal ileum, housed individually, and assigned to 1 of 4 dietary treatments in a complete randomized design. Diets were arranged in a 2 Ã Â Ã Â 2 factorial by adding 0% or 0.017% xylanase (Econase XT, Ab Vista) to corn-soybean meal diets with 0% (lower fiber: LF) or 30% (higher fiber: HF) corn DDGS. Three collection periods consisting of a 2 d fecal collection followed by a 3 d ileal collection occurred at average BW of 46.0 Ã Â Ã Â± 0.4, 54.1 Ã Â Ã Â± 0.4, and 70.3 Ã Â Ã Â± 0.5 kg, respectively, for a total of 24 observations per dietary treatment. Pigs remained on the same diet through the trial to test the impact of BW on enzyme response. Ileal and fecal samples were analyzed to determine the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of GE, DM, NDF, ADF, and nitrogen, and the AID of starch and AA. Apparent digestibility values for fat were corrected for endogenous losses and true ileal digestibility (TID) and true total tract digestibility (TTTD) of fat was reported.
Xylanase inclusion increased the AID of DM, starch, and nitrogen and tended to increase the AID of GE in LF diets, but had no effect in HF diets, resulting in XI Ã Â Ã Â FL interactions (P ≤ 0.059). Xylanase decreased the AID of NDF and tended to decrease the AID of ADF in LF diets, but had no impact in HF diets, resulting in FL Ã Â Ã Â XI interactions (P ≤ 0.097). However, the decrease in fiber digestibility may have been an artifact rather than a true result. Xylanase inclusion tended to decrease the AID of hemicellulose but increase the hindgut disappearance of NDF, ADF, and hemicellulose (P ≤ 0.100). In LF diets, xylanase tended to decrease the ATTD of ADF but increased the ATTD of ADF in HF diets, leading to a trend for a XI Ã Â Ã Â FL interaction. (P = 0.091). As BW increased, xylanase inclusion led to different patterns of the ATTD of DM and protein, but the xylanase treatment did not differ from the non-xylanase treatment at any of the three BW. In conclusion, there was no impact of BW on the enzyme response in 46.0 to 70.3 kg pigs. Xylanase appears to liberate nutrients for digestion in the small intestine in corn-soybean meal diets in growing pigs, but corn DDGS do not appear to be a suitable substrate for the xylanase enzyme.