Aim: This study was conducted to determine the effect of Mentha caucasica on performance, some body measurements and their relation with liveweight in Japanese quails.

Materials and Methods: One hundred and fifty day-old Japanese quail chicks were used in the study. The quails were allocated to 3 groups, each comprising 50 animals, including the control group, Mint Group I (0.75%) and Mint Group II (1.5%). The quails were weighed and their body measurements (head length, head width, body length, leg length, shank length, wing length) were determined on a weekly basis during the 6 weeks posthatching.

Results: The average liveweight of mint groups were determined to be higher than the control group (P<0.05). Generally, feed conversion ratio was decreased in mint groups. According to the control group, quails in mint groups produced eggs at an earlier age. Usually, body measurements increased with advancing age. According to gender and feeding groups, values of some body measurements between differences were significant (P<0.05). Positive, high significant correlations were determined among some body measurements (head length, head width, body length, leg length, shank length, wing length) and liveweight (P<0.05, P<0.01, P<0.001). The most decisive body measurements used in the determination of liveweight were body length and head width.

Conclusion: Some body measurements can be used in the prediction of liveweight and as criteria in selection for liveweight of the Japanese quail.