The effect of dietary yeast cell wall (Saccharomyces cerevisiae) and cinnamon essential oil (Cinnamomum verum) supplementation on growth indices, blood biochemstry and innate immunity of rainbow trout (Oncorhynchus mykiss) fingerlings

The present study was to evaluate the effect of dietary yeast cell wall (Saccharomyces cerevisiae) and cinnamon essential oil (Cinnamomum verum) supplementation on growth indices, serum biochemical parameters and immunity of rainbow trout (Oncorhynchus mykiss) fingerlings. Using a 2×2 factorial experiment, 276 fingerlings (9.67 ± 1.20 g) were fed four different experimental diets (including control diet, diet supplemented with 1.5 % yeast cell wall or 1 % cinnamon essential oil and a diet containing 1.5 % yeast cell wall and 1 % cinnamon essential oil) for a 60-day period. At the end of the trial, specific growth rate and weight gain significantly decreased in fish fed diet supplemented with 1% cinnamon essential oil (P≤0.05), however, feed conversion ratio was not statistically differed amongst treatments (P>0.05). Fish fed diets containing 1% cinnamon essential oil had the highest hepatosomatic index (P≤0.05). The highest red blood cell count and blood hemoglobin content belonged to group fed diet containing 1% cinnamon essential oil (P≤0.05). Simultaneous feeding with yeast cell wall and cinnamon essential oil significantly resulted in higher hematocrit value. Serum alkaline phosphatase activity was significantly increased in group fed diet containing 1.5% yeast cell wall. Dietary cinnamon essential oil supplementation also resulted in lower alkaline phosphatase, aspartate aminotransferase and gamma glutamyltransferase activity of serum (P≤0.05). The highest serum total protein and globulin content and lysozyme activity were observed in fish fed diet only supplemented with yeast cell wall (P≤0.05). In conclusion, dietary cinnamon essential oil and yeast cell wall inclusion resulted in improved immunity of rainbow trout fingerlings.