What is the first limiting amino acid in swine diets?

Lysine is recognized as the first limiting amino acid in swine diets because it is essential for growth, reproduction, and overall health in pigs. In swine nutrition, the term "limiting amino acid" refers to the amino acid that is present in the least amount relative to the needs of the animal, thereby limiting protein synthesis when it is insufficient.

Lysine is particularly vital because it plays a crucial role in the formation of muscle protein, which is important for the growth and development of pigs, especially during the early stages of their life cycle. Since pigs cannot synthesize lysine themselves, it must be provided in their diet in adequate amounts. If lysine is deficient, it can lead to poor growth rates, decreased feed efficiency, and other metabolic issues, reflecting its importance in swine diets.

The other amino acids listed, such as threonine, methionine, and valine, are also essential but generally not as critical as lysine in terms of limiting growth in swine. This is why lysine is specifically identified as the first limiting amino acid in swine nutrition.