Effects Of Fish Meal Substitution Diets Supplemented With Oligochitosan On The Growth Performance, Immune Response And Ability To Infect Vibrio Parahaemolyticus Of Litopenaeus Vannamei

The study was conducted to examine the effect of fish meal substitution diets supplemented with oligochitosan on growth performance,immune response,intestinal health and Ability to infect Vibrio parahaemolyticus infection ability of Litopenaeus vannamei,in order to determine the appropriate amount of oligochitosan in the feed of L.vannamei,the theoretical basis for the research and utilization of the immune stimulant oligochitosan was studied.1.The effect of fish meal substitution diets supplemented with COS on growth performance of Litopenaeus vannameiHealthy shrimp 1400 tail(about 0.9 g)were randomly divided into 7 groups,each group was divided into 4 culture barrels.The experiment lasted for 8 weeks.High fish powder control diet,add 0 g,3 g,6 g,9 g,12 g,15 g(g/kg)10% oligosaccharide premix to the low fish meal based feed respectively,six kinds of low fish meal diets(LFM0,LFM0.3,LFM0.6,LFM0.9,LFM1.2,LFM1.5).We found the growth performance(FAW,WGR,SGR,FCR and SR)have no significant difference in Litopenaeus vannamei among all treatment groups(P>0.05),but LFM0.6 and LFM0.9 two groups of SR increased.There was no significant difference of GLU,CHO and TP in serum,but the level of CHO in LFM0.6 group was lower than that in other groups.There was no significant difference in serum of LDL-C between LFM0,LFM0.3,LFM0.6,LFM0.9 and LFM1.5(P>0.05),but significantly lower than HFM group(P<0.05).In group HFM,LFM0.3,LFM0.6 and LFM0.9 of HDL-C were significantly higher than those in group LFM0(P<0.05),but there was no significant difference between them(P>0.05).2.The effect of fish meal substitution diets supplemented with COS on inflammatory factor mRNA expression of genes and tissue morphology in the intestinal tract and hepatopancreas,of Litopenaeus vannameiThe relative expression of AIF and Cyt-c in hepatopancreas was highest in LFM0 group,and there was no significant difference between the other groups(P>0.05)(mRNA).The relative expressions of HSP70 mRNA in LFM0,LFM1.2 and LFM1.5 groups were significantly higher than those in other groups(P<0.05).The relative expression of TGF-?in LFM0,LFM1.2 and LFM1.5 groups was significantly decreased(P<0.05),while the relative expression of m RNA in other groups was significantly increased(P<0.05).The relative expression of TNF mRNA inLFM0.3 group was significantly lower than that in group HFM,LFM0.6 and LFM0.9(P<0.05).The relative expression of AIF mRNA in HFM,LFM0.3 and LFM0.6 group was significantly lower(P<0.05).The relative expression of Cyt-c mRNA in HFM,LFM0.3,LFM0.6 and LFM0.9group was significantly lower than that in group LFM0 and LFM1.5(P<0.05).The relative expression of HSP70 mRNA in HFM,LFM0.3,LFM0.6 and LFM0.9 groups was significantly lower(P<0.05).The relative expression of TGF-?in HFM and LFM0.6 groups was not significantly different(P>0.05),but significantly higher than that in other groups(P<0.05.The relative expression of TNF mRNA in HFM,LFM0.3 and LFM0.6 groups was not significantly different(P>0.05),which was significantly higher than that of other groups(P<0.05).Compared with LFM0 group,HFM group of liver bodies arranged tightly,liver body between the basement membrane intact,low fish meal group in addition to LFM0 and LFM1.5 group,the other groups were closely arranged with liver,R cells and B cells significantly,especially for LFM0.6,LFM0.9 and LFM1.2 were more closely.Compared with HFM group,LFM0 group,intestinal wall integrity is damaged,villus and intestinal wall detachment,arranged disorderly fracture,and shorter villi,and oligochitosan added group of intestinal wall relatively intact.3.The effect of fish meal substitution diets supplemented with COS on immune response and ability to infect Vibrio parahaemolyticus infection ability of Litopenaeus vannameiThe activities of AKP and NOS in group HFM were significantly higher than those in other groups(P<0.05);the activity of ACP in group LFM0.3 was significantly higher than that in other LFM group(P<0.05);the activities of LZM in HFM,LFM0.3 and LFM0.6 groups were significantly higher than those in other groups(P<0.05).HFM and LFM1.5 group ACP activity was significantly lower than the other groups(P<0.05);hepatopancreas alkaline phosphatase(AKP)activity of HFM group and LFM0.3,LFM0.9 and LFM1.2 group had no significant difference(P>0.05),LFM1.5 group was significantly lower than that of the other groups(P<0.05).Between group HFM and group LFM1.5 hepatopancreas glutathione peroxidase(GSH-PX)activity had no significant difference(P>0.05),significantly lower than the other groups(P<0.05),low fish meal group between the highest LFM0.3,LFM0.6 and LFM0.9 were significantly higher than other groups(P<0.05);the activity of T-SOD in LFM0.3 group was significantly higher than that of HFM group and LFM group(P<0.05);LFM0.9 T-AOC group was significantly higher than that of HFM group and other group LFM(P<0.05).There was no significant difference in the relative expression of mRNA between the HFM and LFM0.3 groups(P>0.05),which was significantly higher than that in other groups(P<0.05).The relative expression of mRNA of HFM in group ACP was significantly higher than that in other groups(P<0.05).The relative expression of mRNA in LFM0.3 and LFM0.6 groups was significantly higher than that in other Crustin groups(P<0.05).The relative expression of Pen 3a and mRNAin HFM,LFM0.6 and LFM0.9 groups was significantly higher than that in other treatments(P<0.05).The relative expression of proPO in LFM0.3 and LFM0.5 groups was the highest,which was significantly higher than that in other mRNA groups(P<0.05).After the infection of Vibrio parahaemolyticus,the mortality of adding chitosan oligosaccharide group was lower than that of LFM0 group.