Chitosan-zinc chelate improves intestinal structure and mucosal function and decreases apoptosis in ileal mucosal epithelial cells in weaned pigs

The present study was conducted to investigate the effects of chitosan (CS)-Zn on intestinal morphology, mucosal epithelial cell apoptosis and mucosal immune function in weanling pigs. A total of 150 weanling barrows with a body weight of 7 center dot 2kg were randomly allocated into five groups. A basal diet without Zn supplementation was used as the control and other four groups were fed the control diet supplemented with 50 or 100mg/kg of Zn as CS-Zn, 100mg/kg of Zn as ZnSO4 and 3000mg/kg of Zn as ZnO, respectively. The feeding trial lasted for 28d. The results showed that serum diamine oxidase activities, d-lactate levels and endotoxin contents were lower in pigs fed dietary 100mg/kg of Zn as CS-Zn or 3000mg/kg of Zn as ZnO than in pigs fed the control or 100mg Zn/kg as ZnSO4 diet. The ratios of the villus height:crypt depth of the duodenum, jejunum and ileum were higher in pigs that received 100mg/kg of Zn as CS-Zn or a high level of Zn as ZnO than in pigs fed the control diet. Moreover, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL)-stained ileal epithelial cells were found in the control group, and apoptotic cells did not appear prominently in pigs that received the 100mg/kg of CS-Zn or ZnO diet. Secretory IgA concentration in ileal mucus was increased in the dietary group that received 100mg/kg of CS-Zn or ZnO. These results indicated that dietary 100mg CS-Zn/kg had similar biological effects to dietary 3000mg ZnO/kg on intestinal morphology, mucosal epithelial cell apoptosis and mucosal immune function.