RESUMEN
This study was conducted to explore the effect of graded levels of pyrroloquinoline quinone disodium (PQQ·Na2) on the performance and intestinal development of weaned pigs. A total of 216 pigs weaned at 28 d were assigned in a randomized complete block design to 6 diets containing 0, 1.5, 3.0, 4.5, 6.0, or 7.5 mg/kg PQQ·Na2 for 28 d. Performance, diarrhea incidence, intestinal morphology, redox status, cytokines, and the expression of tight junction proteins were determined. Pigs had increased ADG (linear, P < 0.01), G:F (quadratic, P < 0.01), and lower diarrhea incidence (P < 0.01) with the increase of PQQ·Na2 supplementation. Villus height increased (quadratic, P < 0.01) in all segments of the small intestine, and crypt depth in the duodenum and jejunum was decreased (linear, P < 0.05) in pigs with the increase of PQQ·Na2 supplementation. Pigs fed PQQ·Na2-supplemented diets had higher (P < 0.05) activities of antioxidant enzymes including total superoxide dismutase in duodenum, jejunum, and ileum; glutathione peroxidase (GSH-Px) in jejunum and ileum; catalase (CAT) in duodenum and ileum; and lower (P < 0.05) malondialdehyde concentrations in the intestinal mucosa of all segments. In the intestinal mucosa, cytokines including interleukin (IL)-1ß, IL-2, and interferon-γ were significantly decreased (P < 0.05) in pigs fed PQQ·Na2-supplemented diets. The protein expression of zonula occluden protein-1 (ZO-1) and occludin in the jejunum was significantly increased (P < 0.05) in pigs fed diets containing PQQ·Na2. In conclusion, these results have indicated that dietary PQQ·Na2 supplementation improves growth performance and gut health in weaned pigs. Moreover, pigs fed diet with as low as 1.5-mg/kg PQQ·Na2 have better performance compared with pigs fed no PQQ·Na2-supplemented diet; pigs fed diet with 4.5-mg/kg PQQ·Na2 have highest G:F among treatments during the whole period.