LAUSR

There is increasing interest in feeding higher-fiber coproducts to weaned pigs due to their potential benefits on gut function and microbiota. However, young pigs are not efficient at utilizing fibrous coproducts. Exogenous carbohydrases can be used to improve nutrient utilization and growth of pigs fed higher levels of coproducts. Previous results regarding the impact of carbohydrases on performance in pigs have been inconsistent, thus a better understanding of associated mechanisms is needed. Using 460 weaned pigs (6.4 ± 0.1 kg), our first study showed that a carbohydrase enzyme blend (EB) improved ADG of weaned pigs fed higher-fiber diets (with added DDGS and wheat middlings) over a 28-d experimental period (P < 0.05). Pigs fed EB-supplemented diets had lower urinary lactulose:mannitol ratio, decreased plasma IL-8 concentration, and greater ileal CLDN3 (claudin 3) mRNA abundance, compared with those fed diets without EB (P < 0.05). These changes may partly explain the improved growth, providing mode of action evidence for carbohydrase in improving performance of weaned pigs. Carbohydrases may also exert prebiotic effects through release of oligosaccharides from fiber degradation. Thus, carbohydrases and dietary fiber may improve disease resilience of young pigs against bacterial infections, for example, enterotoxigenic Escherichia coli (ETEC) induced post-weaning diarrhea. Our second study evaluated the impact of soluble versus insoluble fiber with or without carbohydrases in newly weaned pigs (n = 60; 6.9 ± 0.07 kg) challenged with F18 ETEC. A diet containing a soluble and highly fermentable fiber from sugar beet pulp with added carbohydrases improved (P < 0.05) ADG, tended to increase (P < 0.10) ileal OCLN (occludin) mRNA, increased (P < 0.05) colonic OCLN mRNA, and tended to decrease (P < 0.10) ileal Escherichia-Shigella compared with ETEC-challenged control. Collectively, appropriate use of exogenous carbohydrases in higher-fiber diets (with the right type and amount of enzyme substrate) is promising in improving gut health and growth performance in weaned pigs.