Oregano Oil Combined with Macleaya Cordata Oral Solution Improves the Growth Performance and Immune Response of Broilers

SIMPLE SUMMARY: Developing safe and effective antibiotic growth promoters (AGPs) substitutes is particularly important to improve animal health and production performance. As an essential plant oil, the oregano oil's main bioactive substance is carvacrol, which has been proven to have antioxidant, anti-inflammatory, antibacterial, and antiviral properties. The sanguinarine from macleaya cordata is the primary bioactive substance. Sanguinarine has anti-tumor, immune-enhancing, antibacterial, and anti-inflammatory effects. However, it has not been reported whether the compatibility of oregano oil and macleaya cordata extract could produce better results. This study is the first to report the effect of oregano oil combined with macleaya cordata oral solution on the growth of broilers. The oregano oil combined with macleaya cordata oral solution significantly improved the growth performance of broilers. At the same time, serum biochemical indices, serum antioxidant indices, serum immune indices, serum cytokines, and intestinal morphology were significantly improved. In summary, our results demonstrated that the mixed solution of oregano oil and macleaya cordata has substantial potential to be an alternative to AGPs for broilers to reduce costs and improve benefits. This study provides basic data and technical support for further research. ABSTRACT: The abuse of AGPs in animal husbandry has led to severe problems such as drug resistance and ecological, and environmental destruction, which seriously threaten human health and public health security. In recent years, extracts of oregano oil and macleaya cordata have become a hot spot in the research and application of AGP substitutes for their safety and high efficiency. This study is the first to report the effect of oregano oil combined with macleaya cordata oral solution on broiler growth performance. A total of 960 one-day-old broiler chickens were randomly divided into four treatment groups (240 chickens per group). Each treatment group was divided into six replicate groups (40 birds per replicate group). There were four groups in this study: the solvent control group, the oregano essential oil combined with macleaya cordata extract oral solution group (OS group), the oregano essential oil oral solution group (OEO group), and the macleaya cordata extract oral solution group (MCE group). Two chickens from each replicate group were collected and mixed into a composite sample. Six composite samples were obtained for each treatment group. The results showed that the oregano oil combined with macleaya cordata oral solution significantly improved the growth performance of broiler chickens. At the same time, serum biochemical indices, serum antioxidant indices, serum immune indices, serum cytokines, and intestinal morphology were significantly improved by the OS group. This study shows that oregano oil combined with macleaya cordata oral solution has substantial potential to be an alternative to AGPs for broilers.