Amino acids and protein
Protein is the second largest contributor to the cost of swine diets following energy. Protein is essential for pigs to have an adequate growth and muscle development. There is no specific requirement for protein per se for pigs, but rather for the individual components that make up proteins, amino acids. The amino acid profile and digestibility are important determinants of quality of dietary protein, particularly for lysine. Lysine content and digestibility often dictate the quality of a protein source because it is the most limiting amino acid in most swine diets.
The main protein source for swine is soybean meal owing to its high quality and availability. The main alternative plant proteins used to replace soybean meal in swine diets are canola meal, sunflower meal, cottonseed meal, and field peas. In early nursery diets, animal proteins and specialty soybean products are commonly used to replace soybean meal to attenuate the hypersensitivity reaction to soybean and encourage feed intake in weanling pigs.