Aim: In the present study, peppermint oil was added to the ration of Japanese quail (Coturnix coturnix japonica) and it was aimed to shed light on similar studies in the future by examining its effect on liver tissue by light microscopy.

Materials and Methods: In the study, 10-day old, 40 Japanese quails were used. There were 4 groups of 10 chicks, each with 5 males and 5 females. Groups; Control group 0.3% sunflower oil (SO)+0.0% peppermint oil (PO), the other three groups 0.2% (SO) +0.1% (PO); 0.1% (SO)+ 0.2% (PO) and 0.0% (SO)+0.3% (PO). Created by adding oil ad libitum. From the paraffin blocks prepared by routine tissue follow-up from the liver, sections were taken with a rotary microtome. Hematoxylin-Eosin stained preparations were examined under a light microscope.

Results: The lobule structure divided by the septum interlobaris was not seen in the liver. A small amount of inter lobuler interstitium and consequently the triple structure (trias hepatica) expected to coexist in the hepatic lobes, contrary to what is known, was scattered. It was observed that simple hepatosteatosis occurred in parallel with the increasing fat ratio in the diet.

Conclusion: It has been observed that peppermint oil, which contributes to increase the yield by increasing protein synthesis and feed utilization, as well as providing a healthy breeding opportunity with its antimicrobial and immunomodulatory effect, should be given at an appropriate dose in order to benefit from these positive properties.