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Weaning is a stressful event in the life of piglets that often causes decreased growth performance and increased diarrhea. In the past, large amounts of antibiotics have been used in the feed to reduce weanling stress. However, nowadays essential oils are biosynthesized as potential substitutes for the antibiotics. In this context, tea tree oil (TTO) was shown to have anti-inflammation and anti-tumor functions. Moreover, previous studies have demonstrated that TTO can reduce diarrhea and improve the growth performance of weanling piglets. Therefore, the aim of the present study was to discover the effects of TTO on the intestinal mucosal immunity of weanling piglets. For that purpose, a total of ninety 21-day-old weanling piglets (6.73 ± 0.12 kg) were randomly allotted into 5 treatments: (i) a control group (CON), fed with a basal diet; (ii) an antibiotic group (ANT), fed with an antibiotic-supplemented diet; or the (iii) low-, (iv) middle- and (v) high-level TTO-supplemented groups (LTO, MTO and HTO), fed with 50 mg/kg, 100 mg/kg and 150 mg/kg TTO added diets, respectively.
As a result, after 21 days of study, TTO supplementation increased the ADFI and showed a trend of increased ADG of the weaned piglets. The villus length of the jejunum and the V/C ratio of all of three segments of the small intestine were improved by the TTO treatments. TTO supplementation also increased contents of IL-2 in the jejunum and in the ileum, IL-10 in the jejunum and interferon-γ in the ileum. The gene expression of IL-1ß and IL-10 in the jejunum, and tumor necrosis factor-α and occludin in the ileum were all upregulated under the TTO treatments. TTO supplementation also increased the gene expression of heat shock proteins (Hsp)60, Hsp70 and Hsp90. In addition, TTO supplementation activated Notch2 signaling in the small intestine. Although ANT supplementation did also improve intestinal development, increase cytokines secretion, upregulate the gene expression of tight junction proteins and activate the gene expression of Notch2 signaling, TTO exhibited better results.
In conclusion, TTO supplementation could improve the intestinal mucosal immunity of weaning piglets, with better effects than those of the antibiotics, probably due to the activation of Notch2 signaling.
Dong, L., Liu, J., Zhong, Z., Wang, S., Wang, H., Huo, Y., ... & Yu, L. (2019). Dietary tea tree oil supplementation improves the intestinal mucosal immunity of weanling piglets. Animal Feed Science and Technology, 255, 114209. https://doi.org/10.1016/j.anifeedsci.2019.114209
