Physiological function and application of dietary fiber in pig nutrition: A review

Dietary fiber (DF), divided into soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), has attracted increasing attention in the field of pig nutrition. Although DF reduces nutrient digestibility and inhibits energy deposition in most cases, fiber-rich feeds have been widely used in pig diets. This is not only because of lower feed costs, but also from the continuous discovery about the nutritional value of DF, mainly including the improvement of piglet intestinal health and sow reproductive performance. The addition timing has also been further considered, which potentially enables the nutritional value of DF to be accurately used in applicable pig models. Furthermore, fiber degrading enzymes have been shown to alleviate the anti-nutritional effects of DF and have ensured the improvement effect of fiber on intestinal health in young piglet models. However, the regulatory effect of fiber on pork quality is still unclear, which requires consideration of the wide range of fiber sources and the complexity of the basic diet composition, as well as the impact of pig breeds. Taken together, future research needs to gain more insight into the combined effects of SDF and IDF, processing methods, and addition timing to improve the nutritional value of DF, and further explore the physiological functions and regulatory mechanisms of DF fermentation products short-chain fatty acids in pigs.