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Genomic selection for resistance to bacterial cold water disease Keith Drynan, Troutlodge
Bacterial Cold Water Disease (BCWD), also known as rainbow trout fry syndrome or flavobacteriosis, is a serious contributor to losses in the commercial rearing of rainbow trout (Oncorhynchus mykiss) in almost every region in which it is farmed. The condition is caused by the bacteria Flavobacterium psychrophilum, a gram-negative rod-shaped bacteria, with symptoms including lethargy, inappetence and most commonly tissue erosion around the caudal fin. Behavioral changes such as spiral swimming may also accompany infection and depending on the life cycle stage of the infected group, mortality rates may vary. In addition to the acute responses, BCWD can result in chronic infections with long term impacts on the population and can
flare up again after stressful events such as vaccination, grading and smoltification, as well as persistence in reducing quality of fish produced due to induced skeletal deformities.
BCWD issues BCWD can be difficult to detect and differentially diagnose, as the bacteria can be difficult and slow to incubate on the necessary specialist agar required to generate easily identifiable yellow colonies. Unfortunately, field diagnosis is often required to prompt treatment of the population with antibiotics such as terramycin and florfenicol, although the bacteria have been noted to develop resistance over
Hatchery Feed & Management Vol 8 Issue 3 2020