Use of a probiotic to control lactococcosis and streptococcosis in rainbow trout, Oncorhynchus mykiss (Walbaum)

J. Brunt, B. Austin

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187 Citations (Scopus)


From a comparison of 125 bacterial isolates recovered from the digestive tract of rainbow trout, Oncorhynchus mykiss, and carp, Cyprinus sp., a culture was obtained which was effective at preventing clinical disease caused by Lactococcus garvieae and Streptococcus iniae when used as a feed additive. The culture, Aeromonas sobria GC2, was incorporated into the feed and fed to rainbow trout (average weight = 20 g) for 14 days at a dose equivalent to 5 × 107 cells g−1 of feed. Whereas the untreated controls experienced losses of 75–100% when challenged intraperitoneally with L. garvieae and S. iniae, the probiotic-treated groups remained healthy with total mortalities of only 0–6%. Formalized and sonicated preparations of GC2 and cell-free supernatant fared less well. The mode of action reflected stimulation of innate immunity, namely an increased number of leucocytes and enhanced phagocytic and respiratory burst activity.
Original languageEnglish
Pages (from-to)693-701
Number of pages9
JournalJournal of Fish Diseases
Issue number12
Publication statusPublished - Dec 2005

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