In extrusion, cereal grains are processed under conditions of heat and pressure. Like other types of heat treatment, extrusion may reduce the concentration of antinutritional factors. Extrusion also gelatinizes starch, improving its digestibility. Improved digestibility of starch should, in turn, lead to an increase in digestible energy. Extrusion has also been shown in some studies to solubilize the insoluble fraction of the fiber which would also increase fiber digestibility and digestible energy.

Corn is a high starch ingredient, while oats are high in fiber. An experiment was conducted to determine the effects of extruding corn and oats on the apparent total tract digestibility (ATTD) of energy and fiber when fed to growing pigs.

Global production of rice is third in terms of total tonnage after corn and wheat. Rice is grown to produce polished white rice for human consumption. However, harvested rice, called paddy rice or rough rice, needs to be dehulled, which results in production of brown rice. The outer brown bran layer of brown rice, known as rice bran, also needs to be removed before polished white rice is produced. Approximately 20% of the paddy rice is hulls and the bran fraction is 8 to 10%, so only 70% of the paddy rice will become polished rice. Rice bran is high in fiber, and also contains about 15% crude protein and 14 to 20% fat. Rice bran can be fed as full fat rice bran or defatted rice bran. During milling of the rice, some kernels may get broken and cannot be used for human consumption. These broken kernels are known as broken rice or brewers rice and may also be used in animal feeding. Broken rice is high in starch and contains little fat, fiber, or protein.

Both rice bran and broken rice may be fed to pigs, but these ingredients are poorly characterized in terms of nutritional value. An experiment was, therefore, conducted to determine the standardized ileal digestibility (SID) of crude protein and amino acids in broken rice, two sources of full fat rice bran (FFRB), and defatted rice bran (DFRB) fed to growing pigs.

Distillers dried grains with solubles (DDGS), a co-product of the ethanol industry, is an affordable source of energy and protein in pig diets. DDGS contains more gross energy than corn, but the energy is less digestible because of the high concentration of insoluble fiber in DDGS. If the fiber in DDGS could be made more soluble with pretreatment, its feed value would be improved.

An experiment was conducted to determine the effects of physical, chemical, and enzymatic pretreatments on the concentrations of digestible (DE) and metabolizable (ME) energy and on the apparent total tract digestibility (ATTD) of gross energy, organic matter, acid detergent fiber (ADF), and neutral (NDF) detergent fiber.

Soybean meal is the most common source of protein in swine diets in the United States. However, conventional soybean meal contains antinutritional factors such as antigenic proteins, oligosaccharides, lectins, and trypsin inhibitors that limit its use in diets fed to weanling pigs. Methods of processing soybean meal to remove antinutritional factors have been developed. These include enzyme treatment, fermentation, and the removal of soluble carbohydrates.

Like soybean meal, rapeseed products are usually not fed to weanling pigs due to the presence of glucosinolates and relatively high concentrations of fiber in these products. Previous research has shown that fermentation of soybean meal can reduce antinutritional factors and fiber concentrations. An experiment was conducted to determine the apparent total tract digestibility (ATTD) of energy and concentrations of digestible (DE) and metabolizable (ME) energy in four sources of processed soybean products, conventional soybean meal, conventional 00-rapeseed expellers, and in a fermented mixture of co-products including 00-rapeseed expellers, wheat bran, potato peel, and soy molasses.

Results of experiments in Europe have indicated that the apparent total tract digestibility (ATTD) of gross energy and nutrients, as well as the concentration of digestible (DE) and metabolizable (ME) energy, is greater in gestating sows fed close to their maintenance requirement than in growing pigs allowed ad libitum access to feed.

However, no data from North America for the comparative digestibility of energy and nutrients in sows and growing pigs have been reported. Therefore, an experiment was conducted to compare the digestibility of energy and nutrients in sows and growing pigs. A second objective was to develop equations to predict digestibility of energy and nutrients in sows from digestibility values obtained in growing pigs.

Calcium supplementation is important for swine diets because most commonly used feed ingredients have low concentrations of calcium. In a typical corn-soybean meal diet for a growing pig, the corn and soybean meal contribute only about 16% of the total calcium, with the rest coming from supplements. Apparent total tract digestibility (ATTD) values for calcium have not been reported for many common ingredients, and no values for the standardized total tract digestibility (STTD) of calcium have been reported. Therefore, an experiment was conducted to determine the ATTD and STTD of calcium in five calcium supplements.

An additional objective was to test the hypothesis that inclusion of microbial phytase in the diets increases the ATTD and STTD of calcium. Results of previous research has indicated that inclusion of microbial phytase in swine diets often increases the digestibility of calcium, but the effect of phytase on the STTD of calcium in individual ingredients has not been reported.

One factor that affects the chemical composition of soybeans and soybean meal is where the beans were grown. For instance, soybeans grown in the northern United States contain less crude protein than soybeans grown further south. As a result, soybean meal produced from beans grown in the Northern United States often contain less crude protein than soybean meal produced from beans grown further south. However, less is known about how the concentrations of digestible (DE), metabolizable (ME), and net (NE) energy differs among meals produced from soybeans grown in different areas of the U.S. Therefore, an experiment was conducted to determine the digestibility of energy and concentrations of DE, ME, and NE in soybean meal produced from soybeans grown in different areas of the U.S. and fed to growing pigs.

Canola meal can be used as a source of protein in swine diets, but conventional canola meal contains less protein than soybean meal. In recent years, new varieties of canola have been developed with seeds that contain more protein and less fiber than conventional canola seeds. The meal from these new varieties of canola has a protein content similar to that of soybean meal.

Previous research at the University of Illinois demonstrated that diets containing at least 30% high protein canola meal (CM-HP) or conventional canola meal (CM-CV) could be fed to nursery pigs without reducing growth performance. It has not yet been determined how much soybean meal can be replaced by conventional or high protein canola meal in diets for growing-finishing pigs without affecting growth performance or carcass characteristics. Therefore, an experiment was performed to determine the optimum inclusion rate of high-protein and conventional meal in diets fed to growing and finishing pigs.