Absorption of amino acids and peptides.

Recent findings regarding peptide and amino acid net flux and transport processes are reviewed. The digestive process, the absorption of end products of protein digestion, net portal-drained visceral flux of peptides and amino acids, peptide-bound and free amino acid transport activities and proteins, transport of peptide-bound amino acids, regulation of PepT1 expression and activity, mediated absorption of free amino acids, and emerging concepts for the role of amino acid transporters are discussed. The chapter provides evidence that the gastrointestinal epithelia of pigs, chickens, sheep and cattle possess a large capacity to digest proteins and absorb their constituent amino acids by the same mechanisms as other animals, although some distinctions exist.