Effects of alfalfa meal on protease and amylase activities of common carps

An experiment was conducted using 1 200 carps to study the effects of alfalfa meal on the activity of digestive enzymes. Carps were randomly divided into five treatments according to a random factorial arrangement, each treatment represented by three replicates of 80 carps each .Carps were fed with diet containing 0(control), 40, 80, 120 and 160 g/kg (group 1,2,3,4, respectively )alfalfa meal during the period of 50 days，and activity of protease and amylase in carp's foregut, midgut, hindgut and hepatopancreas were investigated. The results showed that: 1) Protease activity in foregut of carps fed with 80 g/kg alfalfa meal was significantly enhanced compared to the control and group 4 (P0.05), but there was no significant difference between group 1 and group 3 (P0.05). Protease activity in midgut, hindgut and hepatopancreas of carps had no significant difference compared to the control (P0.05), but they had the same trend: the activity of protease of group 1, 2 and 3 were higher than the control group. 2)Activity of protease in carp's foregut, midgut and hindgut were gradually lowered, And activity of protease in hepatopancreas were far lower than that in guts. 3) Activity of amylase in foregut and midgut of carps fed with 80 g/kg alfalfa meal were significantly enhanced (P0.05). There were no significant difference between the other groups and the control (P0.05). Amylase activity in hindgut had no significant difference compared to the control (P0.05). But alfalfa meal enhanced the activity of amylase in hepatopancreas, group 2 was significantly higher than control (P0.05). The other groups had no significant difference compared to the control (P0.05). 4) There was great difference between activity of amylase in foregut, midgut, hindgut and hepatopancreas. Among the four parts, the activity of amylase ranged from high to low: hepatopancrac hindgut midgut foregut. In summary, appropriate alfalfa meal significantly improved the activities of protease and amylase of common carps, and the activities of protease and amylase were different in different parts of carps.