Effects of garlic (Allium sativum) on growth indices and survival rate, some blood biochemical parameters and digestive enzymes of zebrafish (Danio rerio)

The aims of the present study were to investigate the effects of garlic at four levels including 0 (T_0), 0.10 (T_1), 0.15 (T_2) and 0.20 (T_3) gram of garlic essential oil per kilogram of diet on growth indices and survival rate, some blood biochemical parameters and digestive enzymes of zebrafish (Danio rerio). The larvae were fed from the time of their first active feeding with experimental diets for 60 days. Results showed that the growth indices and survival rates of all groups fed with experimental diets containing garlic were significantly increased as compared to the control group (p<0.05). According to the results, the lowest amounts of glucose (18.35±0.08 mg/dl) and cholesterol (3.55±0.06 mg/dl) were observed in the T_3 group as compared to the other experimental groups and the control group (p<0.05) whereas, the highest amounts of total protein (2.51±0.09 g/dl) were measured in the T_2 and T_3 groups that were significantly different from the control and T_1 groups (p<0.05). Protease enzyme levels were increased in all groups fed with experimental diets containing garlic (p<0.05), but levels of lipase and amylase enzymes were significantly influenced by garlic only in the T2 and T3 groups (p<0.05). The highest levels of amylase (9.11±0.13 U/mg protein), lipase (2.55±0.10 U/mg protein) and protease enzymes (4.03±0.10 U/mg protein) were observed in the T_3 group. There was no significant differences between the levels of protease enzyme in the T_2 and T_3 groups (p>0.05). According to the results of the present study, dietary supplementation of garlic had positive effects on improving the general condition, growth indices and activity of digestive enzymes of zebrafish.

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