Wheat middlings and red dog are two coproducts of the wheat milling process that are used as sources of energy and protein in animal feed. Wheat middlings are granular particles of the wheat endosperm, bran and germ. Red dog consists mainly of the aleurone layer that lies between the bran and the endosperm, along with small particles of bran, germ, and flour. It is often used in extrusion mixtures and as a pellet binder. The composition of wheat middlings varies from mill to mill because of the different conditions under which they are produced.
Wheat and wheat co-products contain more non-starch polysaccharides (NSP) than other grains commonly fed to pigs. Because pigs lack the enzymes needed to digest NSPs, this may affect the digestibility of energy and nutrients. An experiment was conducted to determine the apparent total tract digestibility (ATTD) of gross energy (GE), dry matter (DM), and organic matter (OM), and the concentration of digestible energy (DE) and metabolizable energy (ME) in ten sources of wheat middlings as well as one source of red dog.