A total of 2500 one day old Japanese quail were obtained from a local commercial hatchery and raised over 43 weeks of ages. On week 30, quails were selected according to the weight and the egg production percentages and divided into 4 groups. Experiment was conducted as a completely randomized design with 4 treatments (control, 0.04% bacitracin methylene disalicylate (BMD), 0.05 and 0.1% Origanum vulgare extract) of 10 replicates and 12 quails in each. Feed consumption and egg production were recorded daily on a cage basis, whereas BW was obtained at the start of 30 and at the end of 43 wk of age and body weight changes were calculated. Eggs were collected daily and the weight of all the eggs produced was determined per replicate. Quails were weighed individually before feed distribution at the beginning of the experimental period and at the end of week 43 and BW changes were calculated. Eggs were broken weekly and yolk weight measured after gentle rolling on paper towel to remove adherent white. Determined values were used to calculate fractional yolk weight. Egg quality was measured in two eggs per replicate chosen at random from eggs produced at 43 weeks of age. Eggshell breaking strength was measured with an eggshell force gauge (model-II, Robotmation Co. Ltd., Tokyo, Japan) and shell thickness with an ultrasonic thickness gauge (Echometer 1062, Robotmation Co. Ltd.). Haugh units were measured with automatic egg multi-tester equipment (EMT-5200, Robotmation Co. Ltd.). The Origanum vulgare extract significantly (P≤0.05) decreased plasma cholesterol content and LDL levels and increased HDL concentration. Using the Origanum vulgare extract and BMD in diets improved antibody response against Newcastle disease (ND) and avian influenza (AI) significantly (P≤0.01).
