Approach on the mechanisms of effects of chlortetracycline in the diet on intestinal morphology in weaning piglets

Seventy-two piglets(Duroc×Large white×Landrace) weaned at 21 days were used to study the effects of chlortetracycline on intestinal morphology and cell structure in weaning piglets.The piglets were randomly allotted to three groups,each of which was replicated three times with eight pigs per replication. The piglets were reared on a conventional corn-based diet added by 0(control group),75 mg/kg(test 1),and 150mg/kg chlortetracycline(test 2).All piglets were given ad libitum access to both feed and water.The results showed that addition of 75mg/kg and 150mg/kg chlortetracycline increased AFI by 3.62% and 8.35%(P0.05) and decreased diarrhea rate by 22.10%(P0.05) and 52.23%(P0.01), respectively,as compared with the control group.The lengths of the villi within the jejunal and ileal sections of the small intestine were increased significantly(P0.05) and the crypt depth were decreased significantly(P0.01) as compared with the control group.Addition of 75mg/kg and 150mg/kg chlortetracycline decreased the activities of NF-κB in jejunum by 41.57%(P0.05)and 91.01%(P0.01),and decreased IκK-β mRNA expression 56.16%(P0.05)and 89.72%(P0.01,respectively.Nuclear factor NF-κB and IκB kinase may play an important role in the modulation of macrophage and functions of digestive tract in weaning piglets.