Effects of curcumin on growth performance, jejunal mucosal membrane integrity, morphology and immune status in weaned piglets challenged with enterotoxigenic Escherichia coli

• Dietary curcumin supplementation improved growth performance of weaned piglets.
• The protective effect of curcumin on intestinal mucosa barrier of ETEC-challenged piglets was confirmed.
• Curcumin could be used as an alternative to antibiotics in diets fed to weaned piglet.

The aim of this study was to evaluate the effect of dietary curcumin supplementation on growth performance and intestinal mucosal barrier function of weaned piglets. Fifty piglets, weaned at 21 ± 2 days of age, were randomly allotted to five treatments for 21 days. The dietary treatments were the control (basal diet), and the basal diet supplemented with 50 mg/kg quinocetone, or 200 mg/kg, 300 mg/kg or 400 mg/kg curcumin. The piglets were housed in individual pens and orally challenged with enterotoxigenic Escherichia coli (ETEC) during the preliminary trial period. The jejunal morphology and histology analysis were detected under light microscope. The plasma d-lactate and diamine oxidase (DAO) were determined by using enzymatic spectrophotometric assay. Immunohistochemistry assays were used to examine secretory immunoglobulin (sIgA) protein expression. Real-time PCR was used to determine mRNA levels of cytokine and Toll-like receptor 4 (TLR4) in jejunal mucosa. The results showed that, compared with the control, dietary addition of 300 mg/kg or 400 mg/kg curcumin decreased (P < 0.05) feed/gain ratio and crypt depth, improved (P < 0.05) villus height and villus height:crypt depth ratio, reduced (P < 0.05) plasma d-lactate and DAO activity, up-regulated the protein expression of sIgA (P < 0.05), increased (P < 0.05) the number of goblet cells (GCs) and reduced (P < 0.05) the number of intraepithelial lymphocytes (IELs). The mRNA levels of interleukin 1β (IL-1β) and TLR4 and tumor necrosis factor α (TNF-α) were also decreased (P < 0.05), but mRNA level of interleukin 10 (IL-10) was increased (P < 0.05). There was no difference in the above parameters between the 300 mg/kg and 400 mg/kg curcumin groups. Pigs fed with 50 mg/kg quinocetone also decreased (P < 0.05) feed/gain ratio, increased villus height:crypt depth ratio (P < 0.05), and reduced (P < 0.05) crypt depth and mRNA levels of TLR4. In conclusion, curcumin and the quinocetone have similar effects in improving piglet growth, but dietary addition of 300 mg/kg or 400 mg/kg curcumin was more effective than quinocetone in improving intestinal mucosal barrier integrity, morphology, and immune status of weaned pigs. This indicates that curcumin could be used as a potential feed additive replacing quinocetone in weaned piglets.