While corn is the standard source of energy for swine, soybean meal is the typical protein source for swine diets. The amino acid content of soybean meal complements that of corn. When the price of soybean meal is high, alternate sources of protein are sought. Other plant products can be used as protein sources for swine diets, but pig performance will generally decrease. Cottonseed meal is a popular protein source for cattle, but low lysine and toxins limit its use in swine diets.
Cottonseed meal contains gossypol, which is toxic to swine.
Gossypol binds both lysine and iron, making them unavailable to swine. Peanut meal contains more protein than soybean meal, but less lysine. Cottonseed meal and peanut meal should replace no more than half the lysine from soybean meal in swine diets. Soybeans can provide an excellent source of both energy and lysine, but they contain several compounds that reduce pig performance. Cooked soybeans contain more energy than soybean meal because of their higher fat content.