Several Immunostimulants Improved Growth,antioxidant Ability And Immunity Of Chinese Mitten Crab(Eriocheir Sinensis)

In this study,the effects of immunostimulants on the growth performance,antioxidant capacity,non-specific immunity and disease resistance of Eriocheir sinensis were systematically explored with the traditional physiological and biochemical methods.According to this study,the results could provide reference for the effects of immunostimulant on the growth performance,immune response and disease resistance of E.sinensis.The informations of immunostimulant on crustacean were improved.Moreover,it provides valuable reference for the development of new functional feeds for aquaculture.At the same time,it also provides basic information for disease prevention in the crab industry.1.Effects of four immunostimulants on growth performance,antioxidant capacity and non-specific immunity of juvenile Chinese mitten crabs（Eriocheir sinensis）The aim of this study was to investigate the effects of four different immunopotentiators on growth performance,antioxidant capacity and non-specific immunity of E.sinensis juveniles.Juvenile crabs（0.33±0.00g）were fed to control diet or supplemented with 0.1%,0.15%β-glucan,0.1%,0.2%MOS,1%,2%inulin and0.15%,0.3%Tochu（Eucommia extract）diet.After the eight weeks feeding,the results of the test were as follows:the crabs fed on 0.15%BG and 0.1%MOS supplemented diet showed higher weigh gain（WG）,specific growth rate（SGR）and lower feed conversion ratio（FCR）than those fed on the control diet.In addition,the crab fed immunostimulants supplemented diets significantly enhance the antioxidant capacity of hepatopancreas.The catalase（CAT）activity of juvenile crabs fed with 0.1%BG,0.15%BG and 0.2%MOS feed was significantly higher than those of the crabs fed the control group.And the total antioxidant capacity（T-AOC）activity of crabs fed 0.15%BG,0.2%MOS,0.15%TC and 0.3%TC diets was significantly higher than those of crabs fed control diets.The content of malondialdehyde（MDA）in hepatopancreas was significantly lower in crabs fed with 0.15%BG and 1%IN diets than those of crabs fed control diets.The crabs fed BG,MOS,IN and TC diets significantly increased alkaline phosphatase（AKP）and acid phosphatase（ACP）activities in serum than those fed the control diets.In addition,the crabs fed 0.1%BG diet significantly enhance the serum lysozyme（LZM）avtivities of than those fed the control and 0.3%TC diets.The four immunostimulants had no effects in the survival rate and HSI of E.sinensis.In general,β-glucan,MOS,inulin and Tochu improved antioxidant capacity and non-specific immunity of juvenile Chinese mitten crab.Moreover,β-glucan and mannooligosaccharides can improve the growth performance and feed utilization of E.sinensis.2.Dietary mannan oligosaccharide（MOS）improves growth performance,antioxidant capacity,non-specific immunity and intestinal histology of juvenile Chinese mitten crabs（Eriocheir sinensis）Mannan oligosaccharide（MOS）is one of the common prebiotics used to improve the health and immunity of animals in aquaculture.However,its optimum level and effects on the immune response in crabs is currently unknown.The present study investigated the optimum level of dietary MOS supplementation and its effects on growth performance,antioxidant capacity,non-specific immunity and intestinal morphology of juvenile Chinese mitten crabs（E.sinensis）.Juvenile crabs（2.95±0.05 g）were fed on either a control diet or one of the six diets supplemented with MOS（0.1%,0.2%,0.3%,0.4%,0.5%and 0.6%）.After the eight weeks feeding,the crabs fed on the 0.3%MOS-supplemented diet showed higher weigh gain,specific growth rate and lower feed conversion ratio than those fed on the control diet.The acid phosphatase（ACP）activities were significantly higher in the hemolymph of the crabs fed on the 0.2%MOS diet than those fed on the other diets except the 0.2%MOS diet.The lysozyme（LZM）,ACP and alkaline phosphatase（AKP）activities in the gut were higher in the crabs fed on the 0.1%or0.3%MOS diet compared to those fed on the other diets.The antioxidant capacity was higher in the crabs fed the 0.2%or 0.3%MOS diet than those fed on other the diets.In addition,the mRNA expression of the immune genes（Es-Crustin,Es-Toll₂,Es-Lech and Es-proPO）in the hepatopancreas of crabs fed on the 0.2 or 0.3%MOS diet were significantly up-regulated compared with those fed on the other diets.Duplicature length and width increased significantly in the crabs fed on the0.3%MOS diet.The optimum levels of MOS inclusion were 0.32%,0.2%to 0.30%and 0.27%to 0.29%based on growth performance,antioxidant capacity and immunity,respectively.This study indicates that dietary supplementation of MOS at 0.2%to 0.3%could improve growth,enhance the antioxidant capacity and immunity of E.sinensis.3.Effect of dietary mannan oligosaccharide and its combination with beta glucan or inulin on growth performance,anti-oxidation activity,non-specific immunity and resistance against Aeromonas hydrophila of juvenile Chinese mitten crabs（Eriocheir sinensis）Four feeds were prepared for this test:（1）C（control,no added group）;（2）M(3 mg g^-1 MOS);（3）MB((3 mg g^-1 MOS)+(1.5 mg g^-1β-glucan))and（4）MI((3mg g^-1 MOS)+(10 mg g^-1 inulin)).Juvenile crabs（0.26±0.00g）were fed on these diets for 8-week.The results were as follows:the crabs fed M,MB and MI diets significantly improved weigh gain（WG）and specific growth rate（SGR）than those fed the control diet,and significantly decreased feed conversion ratio（FCR）than that in the control group.Simultaneously,the WG and SGR of the crabs fed MB diets were significantly higher than those fed other three diets,and the FCR was significantly lower than those fed other three diets.The crabs fed M,MB and MI diets showed higher intestinal trypsin activity.The intestinal trypsin activity of MB and MI groups were significantly higher than the M group and the control group Morever,trypsin activity in the hepatopancreas of the crabs fed MB and MI diets was significantly higher than those fed the control diet,and the highest activities were observed in MB group.In addition,crabs fed M,MB and MI diets significantly increased antioxidant enzyme activities,such as superoxide dismutase（SOD）,glutathione peroxidase（GSH-Px）,and total antioxidant capacity（T-AOC）,and significantly reduced malondialdehyde（MDA）content.Crabs fed M,MB and MI significantly increased the activity of the non-specific immune system related enzymes of E.sinensis.The activities of phosphatase（AKP）,acid phosphatase（ACP）,lysozyme（LZM）and phenoloxidase（PO）in intestine of the crab fed MB diet were significantly higher than those fed M diet.And the respiratory burst of crabs fed MB diet were significantly higher than those fed other diets The crabs fed MB diet up-regulated the mRNA levels of immune gene for E.sinensis（ES-PT,ES-Relish,ES-LITAF,ES-MAPK and Crustin）compared with those fed C and M diets.After 3 days of infection with Aeromonas hydrophila,the survival rate of crabs fed M,MB,and MI diets were significantly higher than those fed the control diet.Morever,the survival rate of crabs fed with MB and MI diets was significantly higher than those fed M diets.In conclusion,the combined addition of MOS andβ-glucan or inulin to diets have better improving on the growth performance,antioxidant capacity,non-specific immunity and disease resistance of E.sinensis than the single addition of MOS in diets.