Impact of Xylanase and Glucanase on Oligosaccharide Formation, Carbohydrate Fermentation Patterns, and Nutrient Utilization in the Gastrointestinal Tract of Broilers

Simple Summary Fiber-degrading enzymes are commonly used as feed additives in poultry nutrition to offset the anti-nutritive impact of cereal fibers. These enzymes have been associated with improved nutrient digestion and hindgut fermentation of fibers, and ultimately, improved animal growth. Nevertheless, the underlying mechanisms are not fully clear. The aim of this research was to determine the ability of fiber-degrading enzymes to break fibers down to smaller, more easily fermentable structures and evaluate its implications on feed digestion and fermentation in broilers. It was shown that fiber-degrading enzymes released oligosaccharides in the upper gastrointestinal tract in wheat-fed broilers. This coincided with higher short-chain fatty acid production in the ceca and improved nutrient digestion in the small intestine. Such processes were not observed in maize-fed broilers. The higher impact of enzymes in the wheat-based diet is believed to be related to the more complex structure of maize fibers as well as to the higher nutritional value of maize compared to wheat. This study further establishes the beneficial influence of fiber-degrading enzyme supplementation on nutrient and fiber use. This study aimed at determining how the degradation of cereal non-starch polysaccharides (NSP) by dietary enzymes during feed digestion can influence nutrient digestibility and NSP fermentability in broilers. Ninety-six one-day-old male broilers were assigned to 4 different treatments: control and enzyme-supplemented wheat-based (WC, WE) or maize-based (MC, ME) treatments. Enzyme supplementation with endo-xylanase and endo-glucanase occurred from day 20 onwards. On day 28, digesta samples were collected. Nutrient digestibility, NSP recovery, oligosaccharide profile, and short-chain fatty acids (SCFA) content were determined. Enzyme supplementation in WE resulted in a higher starch (3%; p = 0.004) and protein (5%; p = 0.002) digestion in the ileum compared to WC. Xylanase activity in WE led to in situ formations of arabinoxylan-oligosaccharides consisting of 5 to 26 pentose units in the ileum. This coincided with decreased arabinose (p = 0.059) and xylose (p = 0.036) amounts in the ceca and higher acetate (p = 0.014) and butyrate (p = 0.044) formation in WE compared to WC. Conversely, complete total tract recovery of arabinoxylan in MC and ME suggested poor maize NSP fermentability. Overall, enzyme action improved nutrient digestibility and arabinoxylan fermentability in the wheat-based diet. The lower response of the maize-based diet to enzyme treatment may be related to the recalcitrance of maize arabinoxylan as well as to the high nutritive value of maize.

Automated summary

This study demonstrates that fiber-degrading enzymes can enhance nutrient digestibility and fiber fermentability in broilers, particularly in wheat-based diets, by breaking down fibers into smaller, more easily fermentable structures. Their impact is believed to be higher in wheat-based diets due to the complex structure of maize fibers and the higher nutritional value of maize.