The separate and combined effect of garlic (Allium sativum), ginger (Zingiber officinale) and fennel (Foeniculum vulgare) extracts along with different levels of soybean meal on the growth performance and blood parameters of rainbow trout

The purpose of this study was to determine separate and combined effect of plant extracts of garlic (Allium sativum), ginger (Zingiber officinale) and fennel (Foeniculum vulgare) along with different levels of soybean meal on growth performance and some blood parameters of rainbow trout. plant extracts (1% garlic, 1% ginger, 1% fennel and a mixture including 1% garlic + 1% ginger + 1% fennel) were added to experiment diets at two protein levels of soybean meal (25 and 75%). Three hundred rainbow trouts (4.99±0.26 g) were reared with 10 experiment diets and triplicate groups for 8 weeks. At the end of the experiment, the effect of the experimental treatments on growth performance and some blood parameters was measured. The results showed a significant increase in growth performance (final weight, weight gain, specific growth rate, food conversion ratio and protein efficiency rate) and blood parameters (red blood cell count, white blood cell count, hemoglobin, hematocrit and mean corpuscular hemoglobin (MCH)) in experimental treatments (especially the mixture of plant extracts) compared to the control (without plant extract) (P<0.05). The addition of garlic, ginger and fennel plant extracts (especially the mixture of plant extracts) at different levels of soybean meal (25 and 75%) in the diet of rainbow trout has a significant effect on growth performance and immunity.