Poultry response to high levels of dietary fiber sources varying in physical and chemical characteristics

The ban on the use of antibiotics in feeds as growth promoters in many countries throughout the world has increased the incidence of enteric disorders in poultry. Natural additives, inclusion of whole cereals, feeding coarse mash diets, and increasing the level of fiber in the diets have been explored as nutritional strategies to reduce the incidence of the problem. Traditionally, dietary fiber has been considered a diluent of the diet and, often, an antinutritional factor. However, moderate amounts of fiber might improve the development of organs, enzyme production, and nutrient digestibility in poultry. Some of these effects are a consequence of better gizzard function, with an increase in gastroduodenal refluxes that facilitate the contact between nutrients and digestive enzymes. These effects often result in improved growth and animal health, but the potential benefits depend to a great extent on the physicochemical characteristics of the fiber source. In conclusion, poultry require a minimal amount of fiber in the diet for proper functioning of the digestive organs. The response to fiber inclusion depends on the source and level of dietary fiber and the characteristics of the diet as well as on the physiological status and health of the bird. In particular, the inclusion in the diet of moderate amounts of coarse, insoluble fiber sources, such as oat hulls, at levels between 2 and 3% usually improves the growth performance of broilers fed low-fiber diets.