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Online Journal of Veterinary Research

(Including Medical and Laboratory Research)

Established 1994
ISSN 1328-925X


Volume 25 (11):776-782, 2021.

Effect of Bacillus subtilis probiotic on hematology and biochemistry in

Oncorhynchus mykiss trout infected by Streptococcus iniae


Kamgar M1, Pourgholam R2, Ghiasi M2, Ghane M2,3


Department(S) 1Microbiology, 3Young Researchers Club, Tonekabon Branch, Islamic Azad University, Tonekabon, 2Caspian Sea Ecology Research Center, Sari, Iran.





Kamgar M, Pourgholam R, Ghiasi M, Ghane M., Effect of Bacillus subtilis probiotics on hematology and biochemistry in Oncorhynchus mykiss trout infected by Streptococcus iniae, Onl J Vet Res., 25 (11):776-782, 2021. Groups of 60 Oncorhynchus mykiss (Trout) weighing ~60 grams were placed in freshwater tanks 60 days fed pellet at 2.4% body weight daily. Bacillus subtilis 107 cells g-1 probiotic was fed to satiation 3 times daily 45 days before challenge with 0.1ml intraperitoneal 2107 ml-1 Streptococcus iniae. Controls were also infected but not given probiotic. We monitored mortality and at day 60 blood was taken for lysozyme, IgM, protein, albumin, glucose, urea, alanine (ALT) and aspartate aminotransferase (AST) and alkaline phosphatase. Mortality in fish infected but not given probiotic was 54-60% and 25-31% in those fed probiotic. Compared with infected untreated fish we found increased protein (23%), albumin (19%), IgM 39%, lysozyme (40%) but decreased urea -47%, ALT -25% and alkaline phosphatase -29% in those also infected but also fed probiotic. Findings suggest that Bacillus subtilis probiotics may protect rainbow trout against mortality, liver and renal lesions due to streptococci.


Keywords: Probiotic, Bacillus subtilis, Rainbow trout, Streptococcus iniae, Biochemical parameters.