Espinosa, C. D., and H. H. Stein. 2023. Variability in wheat middlings; are there differences in digestibility, composition among sources?  National Hog Farmer, March/April 2023. Link to full text.

Data for the composition of wheat middlings from flour mills in the U.S. and for the standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) have been published for wheat middlings from the U.S. However, it is not known if the data obtained from wheat middlings from the U.S. also are representative for wheat middlings in Europe. Therefore, an experiment was conducted to test the hypothesis that there are no differences in composition and SID of CP and AA between wheat middlings sourced from flour mills in Europe and in the U.S.

Casas, G. A., D. A. Rodriguez, and H. H. Stein. 2018. Chemical composition and digestibility of energy, dry matter, amino acids, and fiber in wheat middlings and red dog fed to growing pigs. J. Anim. Sci. 96(Suppl. 2):175-176 (Abstr.) Link to abstract (.pdf)

Navarro, D. M. D. L., E. M. A. M. Bruininx, L. de Jong, and H. H. Stein. 2018. Effects of inclusion rate of high fiber dietary ingredients on concentration of digestible and metabolizable energy in mixed diets fed to growing pigs. J. Anim. Sci. 96(Suppl. 2):159 (Abstr.) Link to abstract (.pdf)

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.

Jaworski, N. W. and H. H. Stein. 2017. Disappearance of nutrients and energy in the stomach and small intestine, cecum, and colon of pigs fed corn-soybean meal diets containing distillers dried grains with solubles, wheat middlings, or soybean hulls. J. Anim. Sci. 95:727-739. Link to full text (.pdf)