Evaluation of probiotic properties of Lactobacillus and Enterococcus strains isolated from kefir and its effect on some hematological and growth parameters in rainbow trout (Oncorhynchus Mykiss)

Document Type : Original Article

Authors

1 Department of Aquatic Animal Health and Diseases, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.

2 Department of Aquatic Animal Health and Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

3 Department of Fisheries, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.

4 Department of Pathobiology, School of Veterinary Medicine, Shiraz, Iran, Iran.

Abstract

Kefir grains are a natural source of probiotic strains belonging to the family of lactic acid bacteria. This study aimed to isolate and identify the strains of lactic acid bacteria in kefir. In addition, to evaluating their probiotic properties, the effect of their oral administration on some hematological andgrowth parameters in rainbow trout was also investigated. The findings indicated the isolation and identification of Lactobacillus farraginis and Enterococcus durans strains, which showed important characteristics of probiotic strains, such as resistance to acidic conditions, gastric juice and bile salts, as well as good hydrophobicity and antagonistic activity against some pathogenic strains. A total of 480 fish with an average weight of 41.9±4.2 g in a completely random design, divided into 8 groups of 20 specimens in three replications. Control treatment (basal diet), L1and E1 treatments, respectively receiving (basal diet + L. faraginis) and (basal diet + E. durans) dose of 107 Cfu/g; treatments L2 and E2 receiving dose of 108 (CFU/g); the combined treatments (L1+E1 (5×106 and (L2+E2) 5×107 (CFU/g) and Bactocelltretment as a positive control (basal diet + Pediococcus acidilactici lactis) 1010 (Cfu/g). Sampling of treatments after 45 days from the beginning of the experimentwas done. According to the findings, that total red blood cells, hematocrit, hemoglobin level, mean hemoglobin concentration and growth parameters including BWI, SGR and CF were significantly (P<0.05) increased in L2+E2, Bactocell, L2, and E2 treatments, Whereas, the decrease in FCR in these groups was evident compared to control on. The strains appear to be suitable probiotic candidates for adding to the rainbow trout diet, but this requires further in vitro and in vitro studies.

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