Abstract
An excellent alternative for chemical antimicrobial agents to prevent disease in the shrimp aquaculture is the application of effective probiotics. in this research, the experiments to coferm the results related to the effect of Bacillus vallismortis IS03 bacteria isolated from the digestive tract of western white shrimp in the previous study with the commercial formulation of the probiotic TakCell Plus as a native probiotic in the larval rearing period and resistance to the the pathogenic Vibrio harveyi IS01 was investigated.
Five experimental groups (with three replications) including negative control group (without probiotics), positive control group (commercial probiotics) and different time periods and the method of probiotic supply were investigated in the form of three treatments respectively: T3, T4 and T5. Efficacy evaluation included the effect of probiotics on the physicochemical factors quality of rearing water, the progress of the early larval and postlarval stages, the growth indicators and the quality of the postlarvae, the percentage of survival and exposure to Vibrio harveyi bacteria. Based on these results, growth and health indicators such as total length, carapace length, weight, survival, size difference and ratio of muscle to intestine were significant difference in probiotic treatments than in the control group and in all the above indicators between the treatment of probiotic treatments and the control group(P<0.05). In this study stress tests including salinity and formalin were used to evaluate the quality of postlarvae. The results indicated the positive effect of TakCell Plus probiotic in increasing the tolerance of these stresses in the probiotic group compared to the control. Experimental infection of shrimps and probiotic treatment revealed that the use of probiotics reduced mortality and thus increased the survival of shrimps against infection caused by v. harveyi bacteria under clinical conditions. Therefore, according to the results of this research, in addition to having a significant effect on growth factors, stress tolerance, development of larval and post-larval stages, TakCell Plus probiotic has made shrimps resistant to vibriosis disease and significantly increased survival of shrimps in exposed shrimps. was observed with V. harveyi bacteria (P<0.05).
Keywords: Bacillus vallismortis IS03, probiotic, Litopenaeus vannamei, Breeding center, Survival rate, Vibriosis.