This experiment was performed to investigate the effect of dietary supplementation with olive leaf extract on yield performance of laying quails. A total of 192 Japanese quail (Coturnix coturnix japonica) 60 d old were allocated to 4 treatment groups with 4 replicates containing 12 quails each. Birds were maintained in laying cages and received water and diet ad libitum during the total period of experiment. A 16:8 hours light:dark photoperiod was employed. The experiment lasted for 42 days. The quails received a basal diet (maize and soyabean meal based; 19.1% crude protein (CP), 2.940 kcal/kg metabolizable energy (ME), 3.0% calcium and 0.39% availible phosphorus) that was formulated including vitamins and minerals. The diets were prepared as control (basal diet, group K), basal diet plus 200 mg α-tocopherol acetat/kg (group E), and basal diet plus 80 or 120 ppm Oleuropein (OLE) (group OLE-80 and OLE-120).

At the end of the experiment, the olive leaf extract supplementation in the diets did not have significant effects on the final body weight, the daily weight gain, the average daily feed intake and the feed conversion ratio (FCR) (P>0.05). The lowest egg weight (P<0.01) and egg production (P<0.001) were found in OLE-120 group. The mortality rate were not affected by the treatments (P>0.05).

Saturated fatty acid ratio (SFA) of egg yolk samples were found 37.14 % in OLE-80 group and this value was found lower than other groups.