At the 2011 Kansas Swine Day, researchers J.A. Barnes and colleagues at Kansas State University reported a trial in which a total of 576 pigs (PIC TR4×1050, 106lb initial bodyweight) were used in a 75-day trial to evaluate effects of xylanase (Porzyme 93010; Danisco Animal Nutrition, St. Louis, Missouri) in growing-finishing diets varying in dietary energy and fibre on growth performance, carcass characteristics and nutrient digestibility.

Pens of pigs were randomly allotted to one of six dietary treatments in a 2×3 factorial (with or without xylanase and three dietary energy levels) with eight pigs per pen and 12 replications per treatment. The six treatments consisted of corn-soybean meal-based diets with added dried distillers grains with solubles (DDGS), wheat middlings (midds) and choice white grease (CWG) arranged to make low- (30 per cent DDGS, 12.5 per cent midds, and 0 per cent CWG), medium- (15 per cent DDGS, 6.25 per cent midds, and 1.2 per cent CWG), and high-energy diets (0 per cent DDGS, 0 per cent midds, and 2.4 per cent CWG), with or without xylanase (0 or 4,000 units xylanase per kilogram of diet).

Diets were formulated to contain increasing dietary CWG in the medium- and high-energy treatments to maintain uniform dietary crude fat levels. All diets were fed in meal form and in four phases.

No xylanase × energy interactions (P>0.0.06) occurred for any criteria evaluated.

Overall (days 0 to 75), pigs fed diets with xylanase had poorer average daily gain (P<0.02) than pigs fed diets without added xylanase. No differences were found in any other growth response criteria between pigs fed diets with or without xylanase.

Pigs fed diets with increasing energy had improved (linear; P<0.001) average daily gain and feed:gain ratio with no effect on average daily feed intake.

For carcass traits, increasing energy improved carcass yield (linear; P<0.01) and hot carcass weight (linear; P<0.001) but increased backfat depth (linear; P<0.01). Furthermore, pigs fed diets with increasing energy had lower lean percentage (linear; P<0.003) and jowl fat iodine value (IV; linear; P<0.001).

Apparent faecal digestibility of acid detergent fibre improved (P<0.002) with the addition of dietary xylanase. However, there were no differences in any other nutrient digestibility criteria evaluated.

As dietary energy increased, apparent digestibility of dry matter, nitrogen, fat, gross energy, acid detergent fibre and neutral detergent fibre increased (linear, P<0.02).

Feeding pigs diets with increasing energy levels resulted in improved performance over those fed low-energy diets. Although acid detergent fibre digestibility was increased with xylanase supplementation, growth performance, carcass characteristics and other nutrient digestibility values did not improve.

Reference

Barnes J.A., J.M. DeRouchey, M.D. Tokach, R.D. Goodband, S.S. Dritz and J.L. Nelssen. 2011. Effects of xylanase in growing-finishing diets varying in dietary energy and fibre on growth performance, carcass characteristics and nutrient digestibility. Proceedings on the 2011 Kansas Swine Day p227-239.

Further Reading You can view the full paper by clicking here.