Cinnamon Promotes Growth Performance, Digestive Enzyme, Blood Parameters, and Antioxidant Activity of Rainbow Trout (Oncorhynchus mykiss) in Low-Carbohydrate Diets

This study was conducted to investigate the effect of cinnamon in high- and low carbohydrate diets on the physiology of rainbow trout (Oncorhynchus mykiss (16.12±1.33 g). Six experimental diets including control/LCarb (200 g/kg carbohydrate), LCarb-3C (200 g/kg carbohydrate, 30 g/kg cinnamon), LCarb-5C (200g/kg carbohydrate, 50 g/kg cinnamon), HCarb (300 g/kg carbohydrate), HCarb-3C (300 g/kg carbohydrate, 30 g/kg cinnamon), and HCarb-5C (300 g/kg carbohydrate, 50 g/kg cinnamon) were formulated to feed fish for eight weeks. The results showed that fish fed dietary LCarb-3C (72.64 g) and LCarb-5C (73.17 g) had higher weight gain as compared with treatments without cinnamon (P<0.05). Blood performance in LCarb3C (67.10) was significantly higher than the HCarb-3C group (P<0.05). Fish fed dietary LCarb-3C had the best performance so that cinnamon in this group lowered glucose, total cholesterol, and low-density lipoprotein, improved total protein, and highdensity lipoprotein contents. Supplementation of this herb also improved protease and lipase in LCarb-3C and LCarb-5C groups as compared with control. Individuals fed supplemented diets but not HCarb had a higher superoxide dismutase activity when compared with the control group (P<0.05). Generally, cinnamon improved parameters in this study in fish fed a low-carbohydrate diet rather than a high-carbohydrate diet.