Effects of adding probiotics to the feed on anti-infection and five kinds of immune gene expression of Litopenaeus vannamei

A 3-week feeding experiment and a 2-week Vibrio parahaemolytics infection experiment were conducted to study the effects of adding probiotics to the feed on non-specific immune gene expression and resistance to V.parahaemolytics of L.vannameiinitial body weight(6.95±1.20)g.Litopenaeus vannamei was fed four different diets:Control group(commercial fodder)and experimental group(feed supplemented with Bacillus licheniformis;or with Bacillus subtilis and with mixed diet comprising Bacillus licheniformis/Bacillus subtilis at the ratio of 1:1),the final concentration of probiotics was 10⁷ cfu/g.And real-time PCR method was used to study the non-specific immune gene expression of L.vannamei in Bacillus licheniformis/Bacillus subtilis experimental group,which is the highest protection group after being infected with V.parahaemolytics.The results showed that all probiotics groups can effectively improve the ability of shrimp to resist the V.parahaemolytics's infection,and compound probiotics can better resist the V.parahaemolytics infections,its relative protection ratio is 31.11%.After infection with the V.parahaemolytics,the relative expressions of IMD,penaiedin 3a,proPO,LZM and Crustin were obviously up-regulated in hemolymph of shrimp fed diets supplemented with the compound probiotics(Bacillus licheniformis/Bacillus subtilis)compared to the control during the immunization.In hemolymph,the relative expression of immune deficiency gene,penaiedin 3a,prophenoloxidase,Lysozyme and Crustin were increased to the maximum levels at 18-24 h.The experimental result indicates:adding probiotics to the feed can effectively improve the ability of L.vannamei to resist the V.parahaemolytics infection,and the improvement of this ability may be made through enhancing the disease resistance related gene expression.