PSV-13 - Influence of xylanase supplementation in growing-finishing pigs

Abstract: Xylanase is commonly incorporated into U.S. swine finishing diets due to feed efficiency and livability responses. The mechanisms behind this benefit includes reducing digesta viscosity, releasing entrapped nutrients, and hydrolyzing fiber into key arabinoxylan oligosaccharides fermented by microbe that generate short-chain fatty acids. The objective of this study was to evaluate the efficacy of a xylanase (Econase XT 25; AB Vista, Marlborough, UK) on performance and nutrient digestibility of growing-finishing pigs. The hypothesis tested in this study was that supplementation of xylanase following the transition period until slaughter would improve energy and nutrient digestibility of pigs with positive effects on performance. Over a 96-day test period, 432 mixed sex pigs (21.5 ± 4.25 kg) were randomly assigned to one of the two dietary treatments in 36 pens with 12 animals each and 18 pens per diet. The two test treatments were a control diet (CTR), or the same diet supplemented with 100 g/tonne of xylanase (XYL, 16,000 BXU/kg). Diets were based on wheat, soybean-meal, sunflower meal, and palm oil, and were formulated according to FEDNA (2013) recommendations. The pelleted diets were fed over 2 phases: grower (from day 0 to day 53) and finisher (from day 53 to day 96). Fecal samples were collected directly from the rectum from three pigs per pen randomly selected during 4 consecutive days (from day 91 to 94) and pooled for the evaluation of apparent total tract digestibility (ATTD) of ash, dry and organic matter, protein and energy. Titanium dioxide (TiO₂) was added to the finisher diet as an indigestible marker. Pig livability rate, feed intake, and weight gain were recorded, and feed conversion ratio (FCR) was calculated. Data was analyzed using the Standard Least Square procedure of JMP 17 Pro with block and treatment as fixed effects. Overall, the general health of pigs was good, and no record of disease problems was reported throughout the study, although a 2% improvement in livability was observed in xylanase-supplemented pigs (P = 0.271). No differences were observed on average daily weight gain or average daily feed intake, (P > 0.05), but mortality corrected FCR (mFCR) was 2.7 points lower in XYL compared to CTR treatment (P = 0.040). Xylanase supplementation improved (P < 0.01) the ATTD coefficients of dry matter, organic matter, protein, and energy compared to CTR treatment, and a tendency was found for an improved ash utilization (P = 0.06). Based on the calculation for digestible energy, an improvement of 137 kcal/kg was supplied by the addition of xylanase to the diet. The hypothesis of the study was confirmed as xylanase supplementation of growing-finishing pig diets improved energy and nutrient digestibility and this may have contributed to the observed improvement in diet efficiency.