Effect Of Mannan Oligsaccharide On Growth Performance And Anti-Pathogenic Infection Of Allogynogenetic Crucian Carp(Carassius Auratus Gibelio)

A total of360allogynogenetic crucian carps were randomly divided into five groups The control group was fed with basal diet, the others were the treated groups fed with basal diet supplemented with Og/kg,0.5g/kg, lg/kg,2g/kg,4g/kg dose of mannose oliogosacch-arides. After80days of feeding, the growth, feed conversion rate, viserosomatic indices, hepatosomatic indices, serum serum alkaline phosphatase(AKP), serum glutamic oxalacetic transaminase(GOT), liver total antioxidant capacity (T-AOC), liver superoxide dismutase activity(SOD) and liver malondialdehyde content(MDA) and Heat shock protein70of allogynogenetic crucian carp were investigated.The80-days results showed that there were no significant effect on growth gain rate, feed conversion rate, viserosomatic index, hepatosomatic index, fullness coefficient after feeding at50d or80d except hepatosomatic index in the group of4g/kg MOS.Before the infection of Aeromonas hydrophila, it showed that MOS significantly increased serum alkaline phosphatase activity, serum globulin concentration and total protein concentration(P<0.05) and had no effect on the serum glucose, triglyceride concentrations(P>0.05). After infection, the doses of2g/kg and4g/kg MOS can significant-ly reduce the serum aspartate aminotransferase activity (P<0.05), after infection of7days, alkaline phosphatase, aspartate amino transferase and glucose levels in the doses of2g/kg,4g/kg MOS were closer to the level before infection.Before the infection of Aeromonas hydrophila, it showed that1g/kg,2g/kg,4g/kg MOS significantly increased total antioxidant capacity and there wwer no significant effect on SOD acitivties and MDA contents. After pathogenic infection, SOD activities in the doses of2g/kg,4g/kg MOS at7d after infection were higher than those of the control. MDA content in the doses of2g/kg,4g/kg MOS at1d or at2d after infection were lower than those of the control.Beofre infection, there were no significant effect on HSP70mRNA levels in heart, kidney, spleen and liver of the control. Compared with the control, MOS han no effect on HSP70mRNA level. After7d infection,2g/kg,4g/kg MOS significantly increased HSP70gene expression in the liver (P<0.05) compared with control.After80days feeding MOS, there were significant differences on villus length betwe-en lg/kg,2g/kg group and the control group (P<0.05), but the intestinal villus length/intestinal diameter, villus mesenchymal wide, mucous membrane and the intestinal muscle width were not significantly difference between the treated group and control(P>0.05).So it suggested that MOS had no significant effect on growth performance. However MOS can improve the liver antioxidant capacity and immune ability, increase HSP70gene expression and boost the length of villus length in the intestine.