The Effect Of Chitosan Oligosaccharide Complex With Rare Earth On Cadmium Accumulation In Turbot (Scophthalmus Maximus)

The feeding trials were conducted to investigate the effects of Chitosan Oligosaccharide complex with Rare Earth (COS-Ree) on growth and the cadmium accumulation in turbot ( Scophthalmus maximus ). The results were as follows.Firstly, the trial showed that Cd added in diets could be accumulated by turbot, and the content of Cd in each part of turbot gradually increased as time. Each tissue of accumulation ability of Cd was as follow: Liver > Kidney > Gill > Skeleton > Muscle > Ray> Skin> Serum, and the abilities of liver and kidney were significantly larger than other tissues (P<0.05). Cd could reduce the survival rate (SR), Weight gain (WG) and specific growth rate (SGR) of the turbot. WG and SGR of Cd groups were significantly lower than the control group (P<0.05).Secondly, a feeding trial was conducted to investigate the effect of COS-Ree on the accumulation of Cd in turbot, by adding Cd and COS-Ree of different doses in diets. The content of Cd in turbot of COS-Ree treatment groups were significantly lower than the control group (P<0.05). The SG of 500 mg/kg COS-Ree treatment group was close to the control group, and WG and SRG were significantly lower than the control group (P<0.05).Thirdly, the diets with COS-Ree were fed turbot contaminated by Cd, to investigate the removal of Cd. The contents of COS-Ree in diets were as follows: 125 mg/kg, 250 mg/kg, 500 mg/kg, 1000 mg/kg. The result showed that COS-Ree could remove Cd accumulated by turbot. The advantage of COS-Ree in removal Cd happened in the front two weeks. After one week, the removal rate of 1000 mg/kg COS-Ree group was 20 percent, and the control group was only 7.48 percent. Cd of all tissues decreased, and the content of liver in COS-Ree group were significantly lower than the control group (P<0.05). After two weeks, the removal rate of in liver of 1000 mg/kg COS-Ree group was 26.9 percent, higher than the control group by ten points percentage. The removal of kidney of 500 mg/kg COS-Ree group was the best (18.71 percent ). The muscle and gills of 500 mg/kg and 1000 mg/kg COS-Ree groups removed most. The removal rates of all groups were nearly equal after three weeks. After five weeks, the Cd of liver decreased from 10mg/kg to 5mg/kg, and kidney from 4mg/kg to 2mg/kg. The Cd of muscle was low to 0.015 mg/kg, and gill was 0.07 mg/kg. Finally, after contaminated by Cd, the antioxidase activity of turbot wasdecreased. The diets added with COS-Ree could increase the activity of CAT, POD and SOD, and decrease the content of MDA. COS-Ree could repair injures and improved the resistance of turbot.By adding COS-Ree in diets of turbot, feeding trials were conducted to investigate the effect of COS-Ree on Cd in turbot, guiding the aquaculture and providing guarantee for the aquatic products safety and human health.