Effect of carvacrol essential oils on growth performance and intestinal barrier function in broilers with lipopolysaccharide challenge

The purpose of this study was to evaluate the effects of orally administrated carvacrol essential oils (CEOs) on the function of the intestinal barrier in broilers challenged by lipopolysaccharide (LPS). Eighty 28-day-old Ross 308 broilers were assigned to a 2 × 2 factorial arrangement of treatments (20 pens of 1 chick/treatment). Factors were CEOs (with or without orally administered) and LPS (challenged or non-challenged). Individually housed broilers were randomly assigned to four treatments (n = 20 broilers per treatment: 10 males and 10 females): no CEOs and no LPS challenge (NCEOs + NLPS); CEOs and no LPS challenge (CEOs + NLPS); no CEOs and LPS challenge (NCEOs + LPS); CEOs and LPS challenge (CEOs + LPS); all birds were fed the same diet. The broilers were administered 200 μL CEOs daily for 15 days. Orally administered CEOs significantly (P < 0.05) increased the gene expressions of occludin, claudin-1, claudin-5, zonula occludens-1 (ZO-1) and ZO-2 in the small intestinal mucosa, and increased (P < 0.05) the counts of goblet cell in the small intestinal epithelium; LPS-challenge damaged the intestinal barrier, and significantly (P < 0.05) reduced the gene expression of the aforementioned genes and increased the Escherichia coli (P < 0.05) and Salmonella enumeration (P < 0.05) in the intestine of broilers compared with the NCEOs + NLPS group. Injecting LPS reduced (P < 0.05) the gene expression of sIgA compared with the NCEOs + NLPS group. In summary, the CEOs improved the development of the intestinal barrier, to a certain extent, and repaired the intestinal damage caused by LPS.