S.A Hosseini - Shahid Motahary Cold water Fishes Genetic and breeding Research Center, Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization (AREEO), Yasoj, Iran
P Kochanian - Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology. Khorramshahr, Iran
M Alishahi - Department of Clinical sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz- Iran
T Mohammadian - Department of Clinical sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz- Iran
M Zakeri - Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology. Khorramshahr, Iran

The application of probiotics in aquaculture has been increased in recent years due to the many benefits for fish health. The most important factors in reducing the viability of probiotics during passing through the digestive system are low pH in stomach and proteases and bile salts. Encapsulating of probiotics within biodegradable nanoparticles has been found to increase their viability and efficiency in fish gut. In the current study, the effects of microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan on some of the immunological parameters in rainbow trout (Oncorhynchus mykiss) were evaluated. An experiment was designed with four treatments each with three replicates. ۴۸۰ juvenile O. mykiss average (±SD) initial weight of ۲۵.۵۳±.۸۲ g was assigned to fifteen experimental tanks. Fish in T۱ received Lactobacillus rhamnosus encapsulated by internal emulsification with alginate / chitosan, T۲ were fed with alginate/chitosan enriched free probiotic diet, T۳ received bacteria without any encapsulation and T۴ received basic diet as a control group. All treatments were fed with experimental diets for ۶۰ days. Fish were sampled on days ۳۰ and ۶۰ and some of the immunological parameters consist of Lysozyme, Complement, Total protein, Albumin, Globulin and NBT were measured. Results showed that lysozyme in treatment of encapsulated by internal emulsification significantly was higher than other groups at day ۳۰ and ۶۰ of experiment (p<۰.۰۵). Also, a significant increase was be served in the total protein and globulin in T۱ and T۲ at day ۳۰ compared to the other groups and at day ۶۰ compared to the control group (p<۰.۰۵). Generally, it can be concluded that the microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan has significant effects on some of the immunological parameters in rainbow trout and improved the immune responses in this fish.

Microencapsulation, Lactobacillus rhamnosus, internal emulsification, Alginate/ chitosan, Rainbow trout, Immunological parameters