Effects Of Fermentation Extractum Of Hericium Caput-medusae(Bull.: Fr.)Pers.on Immune Function And Intestinal Microflora Of Grass Carp

The study was conducted to investigate the effects of dietary submerged fermentation concentrate of Hericium caput-medusae(Bull.:Fr.)Pers.(HFC)levels on blood biochemical parameters,resistance against Aeromonas hydrophila,intestinal morphology structure and the influence of the digestive enzyme activity of grass carp.At the same time,the study investigated the effects of the HFC on the Intestinal flora of the grass carp by the PCR-DGGE.In the experiment,600 thelarvae of grass carps were randomly divided into 4 treatments and 3 replicates per treatment with 50 fish in each replicate.The fishes were fed with a basal diet and 3 diets supplemented with 0mg/kg,400mg/kg,800mg/kg,1000mg/kg HFC respectively for 45 days.We determined the contents of total protein(TP),albumin(ALB)and the activity of acid phosphatase(ACP),total super oxide dismutase(T-SOD),lysozyme(LSZ),alkaline phosphatase(AKP)in samples of serum were collected from the fishes on 15 d,30d and 45 d.Meanwhile,serum levels of immunoglobulin M and cytokine interleukin 2(IL-2),interleukin 10(IL-10),tumor necrosis factor alpha(TNF-α)were tested by enzyme-linked immunesorbent assay(ELISA)on the 45 d.At the end of the feeding trial,the fishes were challenged A.Hydrophilainfection.After 96 hours of artificial infection,the survival rate was measured.Results show that the contents of ALB and TP in 1200 mg/kg group was significant higher than that of the 0mg/kg group(p<0.05)after fed with for 30 days.The doses increased the activity of T-SOD,ACP,LSZ and AKP(p<0.05)significantly.The content of IL-2,IL-10 in the 1200 mg/kg group was higher than the control group(p >0.05),and different concentrations of HFC all could improve the survival of grass carp’s resistance of A.Hydrophila.We collected samples of intestinal contents on the 15 d,30d and 45 d.Detecting the intestinal flora of groups by PCR-DGGE technology.The result showed that the microflora was diverse extremelyin the grass crap intestinal.The main advantage of flora bacteria are Firmicutes,Proteobacteria,Actinobacteria and Verrucomicrobia in the grass crap intestinal.Most of them are gram-negative bacteria,and a few gram positive bacteria and the number of harmful bacteria were reduced.The intestinal contents,foregut and hindgut of each group was collected on 15 d,30 d and 45 d.We tested the impact of HFC feeding on grass carp’s digestive function.Measuring the length of intestinal villi and crypt depth by slice method to calculate V/C,the results show that HFC could promote the growth of intestinal villus.Compared with the control group,the V/C rate of foregut increased significantly(p<0.05),while the V/C ratio of hindgut was increased invisibly(p>0.05).Experimental groups were compared with control group.The doses significantly improve the activity of Trypsin(p<0.05),but the activity of Amylas was increased invisibly(p>0.05),and the concentration of 800mg/kg and 1200 mg/kg of HFC could decrease the activity of Lipase enzyme.In conclusion,the addition of 800 to 1200 mg/kg of HFC could improve immune function,the intestinal flora and digestive function of grass carp.