Mucin-producing tissues are prioritized over other tissues for protein synthesis when dietary threonine is limiting

Mucins in mucus are particularly rich in an indispensable amino acid, threonine, and their continuous synthesis and secretion represent a major use of dietary threonine. In piglets, the small intestine is particularly sensitive to a low threonine intake resulting in compromised mucin production. Other epithelial tissues, such as stomach, colon and lung, also synthesize large amounts of mucin but their impact on threonine requirement is not as well known. This study suggested that mucin-producing tissues, such as the small intestine, stomach, colon and lung get higher priority for synthesis when dietary threonine is limiting, compared to muscle, liver and kidney. So if neonates are on a marginal threonine intake, then growth and the functions of other vital tissues are likely compromised at the expense of maintenance of the mucus layer.