As an important olive component, hydroxytyrosol (HT) has good medicinal and health effects. However, its importance in alleviating immune suppression in broilers has not been established. Therefore, we aimed at evaluating the immunomodulatory and antioxidant effects of HT in immune suppressed broilers. Immune suppressed broiler models were established via intraperitoneal injection of 80 mg/kg cyclophosphamide (Cy). Thirty two Cobb 500 male broilers were randomly allocated into 4 groups of 8 each. Broilers in the model (Cy) and HT treatment (Cy+HT) groups were intraperitoneally administered with Cy (80 mg/kg BW) once a day for 3 d. From the 4th d, broilers in the Cy+HT and HT groups were treated with 0.5 mL of 200 mg/L HT solution, once a day, for 7 d. The Cy and Con groups were orally administered with normal saline. On the 14th and 28th d, serum and duodenal samples were obtained for testing. It was found that HT increased villi height (VH)/crypt depth (CD) ratio in the duodenum and suppressed serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels. Moreover, it elevated the expressions of CD4+ and CD8+ T lymphocytes. HT upregulated the mRNA expression levels of interleukin-2 (IL-2), interleukin-4 (IL-4), and interleukin-10 (IL-10), enhanced the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and downregulated malondialdehyde (MDA) levels in Cy-induced immune-suppressed broilers. In conclusion, HT can alleviate immune-suppression as well as enhance immunity and antioxidant activities in the local mucosa of small intestines in broilers. Therefore, it can be used as an immune stimulant. More studies should be performed to confirm our findings and to elucidate on the mechanisms of HT.

Walnut oil (WO) is widely used in traditional medicine, and it has become a dietary supplement in many countries. We isolated walnut oil from Juglans sigillata and evaluated its protective effects on acute intestinal injury, and Toll‐like receptor 4 (TLR4)/nuclear factor‐κB (NF‐κB) signaling pathway in lipopolysaccharide (LPS)‐induced mice was studied. The results showed that the LPS + WO group significantly decreased serum tumor necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), and IL‐1β levels and increased the jejunum superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) levels compared with the LPS group. Walnut oil ameliorated the pathological morphology of the LPS‐induced acute jejunum injury and decreased jejunum cells apoptosis rate and TLR4/NF‐κB protein expression. Furthermore, the expression of the TLR4/NF‐κB pathway key gene mRNA significantly reduced after treatment with walnut oil. This study concludes that walnut oil can exert the protective effect on LPS‐induced acute intestinal injury in mice by inhibiting the TLR4/NF‐κB signaling pathway.