244 The feed enzyme xylanase improves finish pig viability and carcass feed efficiency

This paper presents a novel find that the feed enzyme xylanase (XYL) improves pig viability. Xylanases break down cell wall arabinoxylans to shorter chain xylo-oligomers and these become a food source for beneficial gut microflora. In poultry, an increase in this substrate coincided with a balance shift toward more beneficial microflora. This is hypothesized to support intestinal barrier function and improved host health. A total of 2124 PIC castrate and female pigs (11.7 ± 0.2 kg) were used in a growth assay to approx. 137.9 kg ( ± 0.5 kg). Pigs were placed in a commercial research facility, blocked by gender and genotype, stratified by weight and allocated (34 pigs/pen, 0.70 m2/pig) to diets with 0, 0.075, 0.150 or 0.225 g Danisco Xylanase/kg feed. Treatments were arranged as a 2 × 4 × 3 factorial (sex, diet, genotype) with pen being the experimental unit. Diets were composed of corn, soybean meal, corn DDGS (15.0%), wheat midds (10%) and soy oil (1.0%). Nutrient levels met or exceeded the requirement (PIC 2008). Early nursery diets were medicated, however diets were maintained medication free after 30 kg body weight. Paylean® (Elanco) was used at 5 and 10 mg/kg in the final 2 diets. Pigs were classified as moderately high health based on PRRS and PEDv negative status. Mortality and removal rate, for medical treatment, from 12 kg to harvest was 4.16%. Under these conditions, increasing XYL dose tended to reduce mortality (3.99, 3.51, 2.25, 2.39%, SEM = 0.98, linear P = 0.175). Death loss for pigs that remained in test pens (excluded medical pens) averaged 3.39, 2.32, 1.90, 1.62%, SEM = 0.82, linear P = 0.126). Carcass ADG and G:F ratio was computed as the difference between estimated initial carcass weight (0.74 × BW) and plant carcass weight. Carcass ADG was not improved but carcass FCR improved as XYL increased (0.286, 0.287, 0.291, 0.290, P = 0.012, SEM = 0.0015). This occurred, despite no improvement in whole-body G:F ratio, because carcass yield tended to improve with dose: 73.9, 74.0, 74.1, 74.3% (P = 0.160 linear). When gain was expressed on a pen basis (viable pigs × gain), whole-body and carcass gain improved in a linear manner (P = 0.071, P = 0.047); the latter averaged 2892, 2926, 3104, 3035 kg/pen (SEM, 66.4). This study is the first to show that the feed enzyme XYL improves pig viability and in a dose related manner; even under high health conditions and for progeny of 3 genotypes (line × trt, P > 0.50). This outcome has implications for animal well-being and reduced enteric antibiotic use.