Feed manufacturing refers to the process of producing animal feed from raw agricultural products. Fodder produced by manufacturing is formulated to meet specific animal nutrition requirements for different species of animals at different life stages. According to the American Feed Industry Association (AFIA), there are four basic steps:

The Washington State Department of Agriculture defines feed as a mix of whole or processed grains, concentrates, and commercial feeds for all species of animals to include customer formula and labeled feeds, and pet feed. These feed are now commercially produced for the livestock, poultry, swine, and fish industries. The commercial production of feed is governed by state and national laws. For example, in Texas, whole or processed grains, concentrates, and commercial feeds with the purpose of feeding wildlife and pets should be duly described in words or animation for distribution by sellers. Most State and Federal codes have clearly stated that commercial feeds should not be adulterated.

Animal feeds have been broadly classified as follows:

The quality of the prepared feed ultimately depends on the quality of the material such as the grain or grass used; the raw material should be of very good quality. Commercial feed manufacturing is an industrial process, and therefore should follow HACCP procedures. The Food and Drug Administration (FDA) defines HACCP as "a management system in which food safety is addressed through the analysis and control of biological, chemical, and physical hazards from raw material production, procurement and handling, to manufacturing, distribution and consumption of the finished product".

The FDA regulates human food and animal feed for poultry, livestock, swine, and fish. Additionally, the FDA regulates pet food, which they estimate feeds over 177 million dogs, cats, and horses in America. Similar to human foods, animal feeds must be unadulterated and wholesome, prepared under good sanitary conditions, and truthfully be labeled to provide the required information to the consumer.

Feed makes up approximately 60% to 80% of the total cost of producing hogs. Manufactured feeds are not merely for satiety but also must provide animals the nutrients required for healthy growth. Formulating a swine ration considers the required nutrients at various growth stages in creating an appropriate feed. Three basic methods are used to formulate swine diets: Pearson square, algebraic equations and linear programs (computers). In recent times, microcomputer programs are available that will balance a diet for many nutrients and assist with economic decisions.

The basic nutrients required are crude protein, metabolizable energy, minerals, vitamins and water. The formulation procedure has both fixed and variable portions. Swine rations are generally based on a ground cereal grain as a carbohydrate source, soybean meal as a protein source, minerals like calcium and phosphorus are added, and vitamins. The feed can be fortified with byproducts of milk, meat by-products, cereal grains; and "specialty products." Antibiotics may also be added to fortify the feed and help the animal's health and growth.

Distillers dried grains with solubles (DDGS), which are rich in energy and protein, have been used in place of corn and soybean meal in some livestock and poultry feeds and corn DDGS have become the most popular, economical, and widely available alternative feed ingredient for use in U.S. swine diets in all phases of production. The U.S. Grain Council reported that corn DDGS is used primarily as an energy source in swine diets because it contains approximately the same amount of digestible energy (DE) and metabolizable energy (ME) as corn, although the ME content may be slightly reduced when feeding reduced-oil DDGS.