The available energy and nutrients in feed ingredients are usually determined using a 3-step approach.In the first step, ingredients are analyzed for chemical composition including proximate components, amino acids,minerals, and carbohydrates.The details to which carbohydrates are analyzed depend on the ingredient in case and may include more or less detailed analyses for starch, oligosaccharides, and nonstarch polysaccharides.For high-fat ingredients it may also be appropriate to determine fatty acid composition, and an analysis for the concentration of phytate is needed for all ingredients.Analyses for antinutritional factors, such as glucosinolates in canola meal or gossypol in cottonseed meal, are also needed for these specific ingredients because these components may reduce the digestibility of nutrients in the ingredients.The second step of the evaluation should focus on determining the digestibility of the analyzed nutrients.For energy, minerals, and fiber, a total tract digestibility model is usually used, whereas an ileal digestibility model is used to determine the digestibility of amino acids, starch, sugars, and lipids.For either method, the quantities of excreted nutrients are subtracted from the intake of nutrients to calculate the digestibility of that nutrient, which is assumed to be equivalent to availability.The third step in the evaluation involves formulation of diets based on the determined digestibility values and feeding these diets to pigs to confirm that normal animal performance can be maintained on diets containing the ingredient in question.For meat producing animals, an evaluation of the quality of the produced final products from the animal is also appropriate to ensure that consumers will not react negatively to products produced from diets containing the ingredient that is investigated.