Hematological and biochemical responses of rainbow trout to dietary essential oil of Abies siirica under heat stress

Articles in Press

Document Type : Original Articles

Authors

1 Department of Veterinary Medicine, RUDN University, 6 Miklukho-Maklaya St, Moscow, 117198, Russian Federation

2 Department of Fisheries, Faculty of Agriculture and Natural Resources, Gonbad Kavous University, Gonbad Kavous, Golestan, Iran

3 Inland Waters Aquatics Resources Research Center, Iranian Fisheries Sciences Research Institute, Agricultural Research, Education and Extension Organization, Gorgan, Iran

10.22059/ijvm.2025.398682.1005848

Abstract

Background: Heat stress is a major challenge in aquaculture, often impairing fish growth, health, and productivity, necessitating the exploration of natural feed additives to enhance resilience. Objectives: This study aimed to evaluate the effects of dietary Siberian fir essential oil (SFE) on feed efficiency, production efficiency, and hematobiochemical responses to heat stress in rainbow trout. Methods: SFE was incorporated into the diets at four different concentrations: 0 mg/kg (control; CT), 100 mg/kg (100MG), 200 mg/kg (200MG), and 400 mg/kg (400MG). The fish were fed these diets for 60 days, followed by a 24-hour exposure to heat stress. Results: The results indicated that dietary SFE significantly enhanced both feed efficiency and production efficiency, particularly at the 100 mg/kg level. Furthermore, SFE supplementation led to a marked reduction in the activities of plasma alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, effectively mitigating the elevations of these enzymes following heat stress. Fish treated with SFE exhibited higher levels of red blood cells, hematocrit, hemoglobin, white blood cells, and neutrophil percentages. In contrast, the CT group experienced an increase in mean corpuscular volume and mean corpuscular hemoglobin after stress, suggesting that this group endured a greater level of stress. Conclusion: In conclusion, the findings of this study suggest that dietary supplementation of 100 mg/kg SFE can be regarded as an effective feed additive for trout culture, as it enhances economic viability and strengthens the fish's resistance to heat stress.

Keywords

Iranian Journal of Veterinary Medicine

Articles in Press, Accepted Manuscript
Available Online from 11 November 2025

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