Effect of oregano essential oil supplementation on performance, biochemical, hematological parameters and intestinal histomorphometry of Japanese quail (Coturnix coturnix Japonica)

This study was performed to evaluate the efficacy of two levels of dietary oregano essential oil (OEO) on growth performances, biochemical, hematological parameters, and intestinal histomorphology in Japanese quail. A total number of 99 quail chicks were divided into three groups (33 quails per group): Control, OEO 150 mg kg-1, and OEO 300 mg kg-1 treated groups for 42 days. Feed conversion ratio (FCR), feed intake, weight gain, and edible organ weight were recorded. Biochemical and hematological parameters were determined. Histomorphological examination of hepatic and intestinal tissues was performed. FCR was significantly improved and feed intake was significantly decreased in OEO 150 mg kg-1 group compared to control. No detectable changes were observed in the lipid profile. Meanwhile, total protein, albumin, globulin, and H/L ratio were significantly increased in OEO 300 mg kg-1 at day 21. Uric acid and creatinine were significantly increased in the OEO 300 mg kg-1 group at day 42. A significant increase was observed in the whole thickness of the small intestine in the OEO 150 mg kg-1 group besides a significant increase in villi length, width, and crypt depth. Vacuolar and fatty degeneration of the hepatocytes along with Kupffer cell hypertrophy was observed in OEO 300 mg kg-1 group. It was concluded that OEO 150 mg kg-1 improved the quail’s performance, intestinal histomorphometry as well as hematological parameters with no negative impacts on biochemical parameters.