Drying temperatures and corn varieties that inherently differ in kernel hardness, virtuousness, and protein solubility index may influence nutrient digestibility in corn. However, information about interactive effects of corn source (i.e., endosperm hardness) and drying method on energy and nutrient digestibility is limited. Therefore, an experiment was conducted to test the hypothesis that that the apparent total tract digestibility (ATTD) of gross energy (GE) and total dietary fiber (TDF) is influenced by corn source and drying temperature.

Most diets for weanling pigs contain highly digestible plant and animal proteins, but there is an increasing trend to include more fibrous co-products in diets for pigs due to reduced diet costs. However, feeding diets to nursery pigs with high concentration of dietary fiber may reduce nutrient digestibility, induce intestinal inflammation, and subsequently depress growth performance. Addition of 100 to 200 mg/kg of Cu from Cu hydroxychloride (IntelliBond C^II; Micronutrients USA LLC; Indianapolis, IN) to diets improves feed efficiency and reduces post weaning diarrhea in pigs. However, there are at this point no data to demonstrate the effect of Cu hydroxychloride on intestinal barrier integrity of pigs fed low-fiber or high-fiber diets, and it is not known if Cu hydroxychloride influences immune responses of pigs. Therefore, 2 experiments were conducted to test the hypothesis that inclusion of 150 mg/kg of Cu from Cu hydroxychloride reduces intestinal permeability and subsequently improves growth performance of pigs fed diets without or with high concentration of dietary fiber.

Navarro, D. M. D. L., E. M. A. M. Bruininx, L. de Jong,  and H. H. Stein. 2018. The contribution of digestible and metabolizable energy from high-fiber dietary ingredients is not affected by inclusion rate in mixed diets fed to growing pigs. J. Anim. Sci. 96:1860-1868. Link to abstract

Fiber in feed ingredients used in diets for pigs is mainly used for energy, which is synthesized by microbes in the hindgut of the pig and absorbed in the form of short chained fatty acids. To estimate the energy that a pig can obtain in a particular fibrous ingredient, a digestibility experiment is usually conducted and the digestible energy (DE) and the metabolizable energy (ME) in the ingredient is determined. However, it is not known if the obtained DE and ME values are accurate for all inclusion rates of the feed ingredient in diets.

There are two reasons that differing inclusion rates of high fiber ingredients in diets fed to pigs might result in variable DE and ME values. Because energy from dietary fiber is obtained via hindgut fermentation, there may be a saturation point in the fermentation capacity in the hindgut of growing pigs. In addition, increasing dietary fiber increases the passage rate of feed through the digestive tract and thus reduces time for fermentation. However, it is not known if these potential issues affect the DE and ME in fibrous ingredients fed to pigs. An experiment was conducted to determine effects of inclusion rate of four commonly used high fiber dietary ingredients on the concentration of DE and ME by growing pigs.

Mathai, J. K., H. L. Spangler, H. H. Stein, and K. J. Touchette. 2017. Effects of high neutral detergent fiber diets on the nitrogen balance of pigs fed threonine-limited diets. J. Anim. Sci. 95(Suppl. 5):136 (Abstr.) Link to abstract (.pdf)

Navarro, D. M. D. L., E. M. A. M. Bruininx, L. de Jong, and H. H. Stein. 2017. Chemical composition and physicochemical characteristics of feed ingredients and effects on in vitro ileal and total tract digestibility of dry matter. J. Anim. Sci. 95(Suppl. 5):89-90 (Abstr.) Link to abstract (.pdf)

Dietary fiber is resistant to digestion in the small intestine, but is fermented in the large intestine and the resulting short chain fatty acids provide some energy to the pig. Fermentation occurs to a greater or lesser degree depending on the chemical and physical composition of the fiber; soluble fiber is generally fermented to a greater extent than insoluble fiber.

Bulk density, swelling capacity, water binding capacity, and viscosity of diets fed to pigs vary based on the types of fiber present in the diets. Therefore, an experiment was conducted to test the hypothesis that the physicochemical characteristics of feed ingredients are correlated with the concentrations of digestible energy (DE) and metabolizable energy (ME) and the apparent total tract digestibility (ATTD) of energy, dry matter (DM), and nutrients in corn, wheat, soybean meal (SBM), canola meal, distillers dried grains with solubles (DDGS), corn germ meal, copra meal, sugar beet pulp, solka floc, and pectin.

Rojas, O. J. and H. H. Stein. 2016. Use of feed technology to improve the nutritional value of feed ingredients. Anim. Prod. Sci. 56:1312-1316. Link to full text (.pdf)

Rojas, O. J., E. Vinyeta, and H. H. Stein. 2016. Effects of pelleting, extrusion, or extrusion and pelleting on energy and nutrient digestibility in diets containing different levels of fiber and fed to growing pigs. J. Anim. Sci. 94:1951-1960. Link to full text (.pdf)