Bioefficacy of Laurel (Laurus nobilis L.) Essentials Oil on Lipopolysaccharide-Induced Inflammation in Japanese Quails

The potential use of natural plants and essential oils as feed additives in poultry farming is a popular research area. In the presented study, the effects of laurel essential oil on growth and feed conversion performances, slaughter-carcass characteristics oxidative stress index and histopathological parameters in Japanese quails in LPS-induced inflammation model were investigated. The study groups were established as Control (C), laurel essential oil (LEO) group, lipopolysaccharide (LPS) group, laurel essential oil together with lipopolysaccharide (LEO+LPS) group. The live weights on the 19th, 26th and 33rd days were higher in the LEO+LPS and in the LEO group on the 36th day. Feed utilization was the worst in the LPS and the best in the LEO group. Non-eviscerated carcass yield was lower in the LPS group compared to the control, and the gizzard weight was higher in the LEO, LEO+LPS and LPS groups. The OSI value was observed as highest in the LPS group and the lowest in the LEO group. In addition, OSI value in the LEO group reduced importantly comparing with LEO+LPS group. Liver OSI values did not show any significant difference in all groups. Histopathologically, no significant difference was observed, in terms of fatty liver, congestion, degeneration necrosis and cell infiltration. The addition of laurel increased degeneration, necrosis and desquamation and cell infiltration in the lamina epithelialis in the intestine. In the intestines, cell infiltration was significantly increased in the LPS group compared to the control group. In addition, eosinophilic accumulations were detected in the brain in the LPS group. As a result, it was determined that laurel essential oil improved live weight and feed conversion rate, made a significant contribution to balancing the oxidant-antioxidant capacity ratio, and showed significant bioactivity, especially in terms of turning the negative effect of LPS into positive.