Abstract
In this study, the effects of Ferulago angulata extract on the growth, haematological, and immunological indices of rainbow trout (Oncorhynchus mykiss) fingerlings were evaluated. Basal diet was supplemented with 0 (control), 0.5, 1, and 2 g·kg-1 F. angulata and was randomly allocated to experimental fish of an initial average weight of 7.45 ± 0.02 g. After 8 weeks of experiment, the fish supplemented with F. angulata extract showed increased but non-significant (P > 0.05) growth performance. No significant differences were found between trial control groups in haematological indices such as red blood cell count, haematocrit, and haemoglobin, but there was a significant increase in white blood cells, lymphocytes, neutrophils and monocytes in the F. angulata extract groups (P < 0.05). Also, there were significant differences between the fish supplemented with dietary F. angulata extract and the control group regarding immunological indices, including immunoglobulin M, lysozyme, and classical and alternative complement pathway (P < 0.05). These findings suggest that the administration of F. angulata extract has a positive effect on the immunological indices and the immune system activity in rainbow trout fingerling.
Highlights
Aquaculture industry has one of the most important roles in food production in most countries
Growth indices, including weight gain (WG), feed conversion ratio (FCR) and specific growth rate (SGR) were increased in parallel with increasing Ferulago angulata extract concentration during the experiment, but no significant differences were observed in the treatment group compared with the control group (P > 0.05)
There was a significant increase in WBC, lymphocytes, neutrophils and monocytes of rainbow trout fingerlings supplemented with the F. angulata extract compared to the control group (P < 0.05)
Summary
Aquaculture industry has one of the most important roles in food production in most countries. Nitrite concentrations may cause physiological changes in rainbow trout, e.g. in the haematological and biochemical indices (Zuskova et al 2013) These indices are high risk and weaken the immune system, increasing disease incidence (Shalaby et al 2006). Improving the immune system of the fish, especially in valuable species such as rainbow trout is the most important principle of fish farming. The use of natural plants as growth and immune stimulant factors along with their compounds such as essential oils and herbal extracts has improved the non-specific immune system in fish farming. The phenolic compounds of the plant are antioxidant agents which can inhibit free radicals, so they can be effective in preventing many oxidative diseases such as cancer. This study was carried out to evaluate the effects of F. angulata (Schlecht) Boiss on the growth indices and haematological and immunological indices of rainbow trout (Oncorhynchus mykiss) fingerlings
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