A short‐term dietary administration of 1,8‐cineole and lactic acid alleviates transportation stress in common carp, <i>Cyprinus carpio</i>

Abstract Fish transportation is stressful, causing metabolic stress, oxidative stress, and immunosuppression. Dietary additives can boost fish antioxidant and immune responses; hence, using functional feeds can alleviate the negative effects of transportation in fish. In the present study, common carp (33.2 ± 1.72 g) were fed diets containing 5 g/kg of 1,8‐cineole, lactic acid, or their combination for 2 weeks before being transported in plastic bags for 6 h. Ammonia and alkalinity significantly increased after transportation. The fish showed typical stress responses (increase in plasma cortisol, glucose, lactate, and hepatic alanine aminotransferase and aspartate aminotransferase), hyperammonemia, oxidative stress (increase in hepatic superoxide dismutase, catalase, malondialdehyde and decrease in total antioxidant capacity and reduced glutathione levels) and immunosuppression (decrease in plasma, mucus and gut lysozyme and complement activities and decrease in plasma and mucus bactericidal activities) after transportation. Dietary supplementation with either feed additive significantly reversed the adverse effects of transportation on fish. The combination of 1,8‐cineole and lactic acid resulted in the lowest plasma cortisol level and hepatic alanine aminotransferase activity after transportation. This is the first study reporting the efficiency of a short‐term dietary supplementation with 1,8‐cineole and lactic acid in mitigating the negative effects of transportation in common carp. According to the results, adding 5 g/kg of 1,8‐cineole and lactic acid is recommended to suppress transport stress, including oxidative stress and immunosuppression in common carp.