Evaluation of the effects of diets containing Lactobacillus rhamnosus JCM 1136 microencapsulated with sodium alginate and chitosan on the growth of rainbow trout (Oncorhynchus mykiss).

One of the most important problems in using probiotics in the aquaculture industry is their high mortality rate due to selection of processing conditions before using, storage methods and their adaptation in digestive ducts of aquatic animals. The newest methods to protect and increase the stability of probiotics in intestinal aquatic animal ducts is microencapsulation method. Microencapsulation keep the quality of the probiotics due to production processes, unfavorable gastrointestinal conditions, and environmental storage conditions. In this study, the first Lactobacillus rhamnosus as a probiotic coated with sodium alginate and chitosan, then the viability and potency in tolerating bile pH and stomach simulated conditions in rainbow trout (Oncorhynchu smykiss) were evaluated. After that, microencapsulated probiotics were added to the food pellets by spraying method and were given to rainbow trout juveniles with an average initial weight of 6.23 ± 0.17 g for a period of 60 days. At the end of the experiment, the results showed that the microencapsulated probiotics were more resistant to the stomach simulated conditions in rainbow trout in comparison with the free probiotics treatment as control. Also, the results showed that the growth indices in the treatment, the fish fed feed containing the sodium alginate-chitosan -microencapsulated probiotics had average daily weight gain 0.48 g, weight gain 28.8 ± 0.63 g and weight gain percentage 468.37 ± 16.63% and more efficient than the control treatment (P<0.05).