Authors
1
Department of Aquatic Animal Health and Diseases, Sciences and Research Branch, Islamic Azad University, Tehran, Iran
2
Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran
10.22092/ijfs.2024.132171
Abstract
This study examined the dietary impacts of essential oils from garlic (Allium sativum), black seed (Nigella sativa), and black caraway (Carum carvi) on the hematological and immunological parameters of rainbow trout (Oncorhynchus mykiss). A total of 200 fish, each with an average initial weight of 225 ± 10 g, were divided into five groups, each consisting of three replicates with 40 fish per group. The fish were fed for eight weeks with a diet supplemented with 0.2% of the herbal essential oils, while a control group received an unsupplemented diet. The hematological indices, including hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), the number of red blood cells (RBCs) and white blood cells (WBCs), and immune responses, including serum lysozyme and complement levels (C3 and C4), were studied. The analysis showed no significant differences in erythrocyte indices or leukocyte profiles between the control group and the groups receiving essential oils (p>0.05). The control group exhibited the highest values for RBC, Hb, MCV, MCH, MCHC, Hct, and WBC, while the highest percentages of lymphocytes and monocytes were found in the black seed and black caraway groups, respectively. On day 28 of the experiment, there were no significant differences in lysozyme activity among the control and treatments (p>0.05), while a significant difference was observed for black caraway essential oil on day 56 (p<0.05). A significant difference between the control group and all treatments was reported for C3 value on day 28 (p<0.05). Comparisons from days 28 to 56 indicated significant changes for the control versus mixed essential oil, garlic essential oil, and black caraway essential oil (p<0.05). C4 and plasma protein values showed no significant differences between the control group and treatments on both days (p>0.05), however, significant differences were noted when comparing values from days 28 and 56 for the control and treatments of mixed essential oil, black seed essential oil, and black caraway essential oil (p<0.05). The results of this study demonstrated that dietary garlic essential oil significantly enhanced immune functions and TNF-α expression levels in rainbow trout compared to black caraway or black seed essential oils (p<0.05). However, all essential oils boosted immune parameters like lysozyme activity and complement levels, but garlic essential oil showed the most promising results.
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