Troutlodge has reported laboratory and real-world success with disease-resistant fish. Photo: Troutlodge.

Troutlodge expands genetic selection for resistance

Salmonid egg supplier Troutlodge is expanding the use of genomic selection for resistance to bacterial cold-water disease (BCWD) after real-world success with one of its spawning populations.

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BCWD, also known as rainbow trout fry syndrome or flavobacteriosis, is a serious contributor to losses in almost every region where trout is farmed.

US-based Troutlodge, in collaboration with the US Department of Agriculture, began research around 10 years ago to help solve the issue.

Click on image to enlarge. Graphic: Troutlodge.

Significant improvements

In a news article on the Troutlodge website, senior trout geneticist Kyle Martin said use of genomic selection technology has produced significant improvements in survival through laboratory challenges, and that the company – which is owned by Hendrix Genetics – was starting to receive positive feedback from customers who have been able to buy BCWD-resistant trout eggs since 2017.

He added that laboratory challenge survival data (see graphic) from the company’s May spawning population confirmed that genomic selection can be a highly effective tool to select for improvements in disease resistance. 

“Expanded use of the technology is under way at Troutlodge, with plans for BCWD improvements in additional broodstock groups,” wrote Martin.

“A cooperative project involving both government and academic institutions is also under way, targeting similar improvements in IHNV (infectious hematopoietic necrosis virus) resistance using similar techniques.”

Flavobacteria ‘has disappeared’

Troutlodge quoted a recommendation from Alexander Tautenhahn, of Forellenzucht Trostadt GmbH & Co.KG, a family-owned trout farm and restaurant located in central Germany which is also a distributor of Troutlodge products.

“When Troutlodge offered the first BCWD-enhanced resistance eggs in 2017, we were probably one of the first customers who tried them,” said Tautenhahn. “Now three 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.”

Martin said: “In summary, we are seeing indications that the improved survival in laboratory challenges has translated to improved performance in commercial farms.”  

He added that the expanded use of genomic selection into other strains will be aided by the development of a custom SNP chip for genotyping broodstock. Coming late 2022, eggs selected for BCWD resistance will be available in the November strain, in addition to the May strain.