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Published on Jan. 12, 2021

Industry benefits from improved BCWD resistance

Bacterial Cold Water Disease, also known as Rainbow Trout Fry Syndrome or Flavobacteriosis is a serious contributor to losses in the commercial rearing of Rainbow Trout in almost every region where it is farmed.

Effects of BCWD outbreaks have major economic impact on farmers due to heavy mortality, and increased cost for treatments with antibiotics.  Even for fish that survive, the economic cost continues as the infection causes reduced appetite and slower growth, meaning that fish are slower to reach market size.  In addition, there is an economic cost at harvest as trout previously infected with BCWD frequently exhibit spinal deformity.  This can cause downgrading at the processing plant leading to less returns.

Troutlodge in collaboration with the USDA initiated research roughly 10 years ago to help solve this issue.  The use of genomic selection technology has produced significant improvements in survival through laboratory challenges and Troutlodge strains can provide enhanced resistance to BCWD.

Trout BCWD genommic selection lab results

Figure 1: Results of BCWD laboratory challenges conducted by the USDA on Troutlodge’s May strain.

Laboratory challenge survival data in figure 1 represents selection results from Troutlodge’s May spawning population and confirms that genomic selection can be a highly effective tool to select for improvements in disease resistance.  Expanded use of the technology is underway at Troutlodge, with plans for BCWD improvements in additional broodstock groups.  A cooperative project involving both government and academic institutions is also underway, targeting similar improvements in IHNV resistance using similar techniques.

Troutlodge product selected for BCWD resistance has been commercially available since 2017 and is starting to receive positive feedback from our clients.

“When Troutlodge offered the first BCWD-enhanced resistance eggs in 2017, we were probably one of the first customers who tried them. Now 3 years later we have had several batches and can confirm all the previous problems we had from time to time with Flavobacteria have simply disappeared in these batches. BCWD-enhanced resistance strains are a real advantage of buying Troutlodge trout eggs!”

Alexander Tautenhahn, Forellenzucht Trostadt GmbH & Co.KG

In summary, we are seeing indications that the improved survival in laboratory challenges has translated to improved performance in commercial farms.  The benefits of increased resistance extend beyond improved survival but also the prevention of BCWD outbreaks have other sustainability benefits:

  1. Reduced antibiotic treatment use leading to a positive impact on the environment & reduced costs to farmer.
  2. Prevention of outbreak eliminates associated decreases in appetite and growth, leading to faster time to harvest. No infection means you will see better growth rates.
  3. Reduces downgrading at harvest due to deformity caused by the BCWD pathogen.

The expanded use of genomic selection into other strains will be aided by the development of a custom SNP chip for genotyping our broodstock.  Coming late 2022, eggs selected for BCWD resistance will be available in the November strain, in addition to the May.  To get in touch with a member of our team for more information, please visit our contact page or if you're ready to place your order, complete your order form here.

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