Reducing nitrogen nutrients concentration in dairy food is economic for pig industry. Here, we used finishing pig as model to investigate the effect on colon mucosal barrier and nutrients absorption after reducing crude protein (CP) in dietary from 16 % to 13 %. The results showed that crypt depth, cells, claudin-1 and E-cadherin expression level will not be changed, which implied the integrity of colon mucosal structure. Furthermore, the expressions of ASCT1, EAAT3 and SGLT1 in colon were also maintained at normal levels in 13 % CP dietary. Interestingly, the CAT1 and GLUT2 expression were increased significantly after reducing CP level to 13 %, which might be attributed to the compensatory nutrients absorption. This study implied that 13 % CP was sufficient to maintain normal colon structure and will not change intestinal morphology, which provided a basis for an ideal economic protein feed formula.
KEY WORDS: Amino acid transporter; Pig; Colon; Goblet cell; Tight junction.