Effects of alfalfa (meal and extract) on digestive enzymes and liver composition in juveniles of common carp (Cyprinus carpio)

270 fish (with an average initial weight: 20.04±0.19 g) were randomly distributed in 27 polyethylene tanks and fed by the carp commercial diet. The experimental treatments of 9 groups (4 groups with 3, 6, 9, and 12% of alfalfa powder, 4 groups with 1, 2, 3, and 4% of alcoholic extract and one control group) with three replications were considered for 8 weeks. At the end of the experimental period, the activity of digestive enzymes was measured in terms of U/mg Protein and liver composition. Based on the results, the highest levels of activity of digestive enzymes, amylase (674.74±61.57), lipase (6/21±/096), alkaline phosphatase (452.84±28.18), trypsin (282.05±19.98) and chymotrypsin (0.10±0.001) in the extracts of 3%, 3%, 3%, 4% and 4% extracts, respectively, and the lowest amount of these enzymes were observed respectively with values of 388.17±38.27 (control), 2.51±0.55 (control), 187.7±19.36 (12% powder), 0.030±0.004 (12% powder) and 132.47±11.47 (9% powder) (P <0.05). The highest amount of hepatic glycogen (338.35±192.13 µg/g tissue) was measured in the 3% extract treatment and the lowest amount of hepatic glycogen (607.01±101.23 µg/g tissue was in the control treatment (P <0.05). The highest level of liver lipids (146.51±6.05 mg/g tissue) was observed in the treatment of 6% powder and the lowest level of liver lipids (72.99±4.46 mg/g tissue) was observed in the treatment of 12% powder (P <0.05). According to the present study, adding powder and especially alfalfa extract to the diet can increase the activity of digestive enzymes and increase liver lipid and glycogen at certain levels.