Susceptibility of Atlantic salmon families against winter sore
Etterevaluering
Mattilsynet er forpliktet etter regelverket til å etterevaluere alle forsøk som er betydelig belastende for forsøksdyrene.
Begrunnelse for etterevalueringen
The aim of this study, to compare disease susceptibility against winter sore in different families of Atlantic salmon, was achieved.
Resistance to Moritella viscosa is shown to be hereditary to a certain degree, and results from this study will be used to improve populations by selecting breeding salmon for Moritella resistance. To be able to implement this as a long-term goal, the breeding company is reliant on data being available every year from a challenge test. It is therefore vital that this challenge test is approved in the future.
Three phenotypes were collected per fish in this challenge test: (1) days to death; (2) survival dead/alive; and (3) lesion score. The heritability for all three traits were lower than other traits included in the breeding goal, but consistent with the previous three challenge tests. This low heritability is also consistent with field data that the breeding company has been collecting and indicates that the phenotype collected in the challenge test is robust and reliable.
Since lesions without mortality is not possible, the endpoint of this challenge will inevitably be mortality. A genome-wide association analysis revealed no significant regions of the genome that are linked to resistance, suggesting that this trait is polygenic and genomic selection is the best way forward to ensure progress for this trait.
Up to 1500 animals were applied for and approved used in the experiment. In total 1487 salmon were used. 502 salmon were classified as mildly harmed and 985 were classified as severely harmed. This was 185 salmon more than expected 800 with this severity. This was due to an unexpected high mortality the infection trial. If surviving salmon had wounds scored 2 or 3, we assess that these animals should be classified as moderately harmed.
Resistance to Moritella viscosa is shown to be hereditary to a certain degree, and results from this study will be used to improve populations by selecting breeding salmon for Moritella resistance. To be able to implement this as a long-term goal, the breeding company is reliant on data being available every year from a challenge test. It is therefore vital that this challenge test is approved in the future.
Three phenotypes were collected per fish in this challenge test: (1) days to death; (2) survival dead/alive; and (3) lesion score. The heritability for all three traits were lower than other traits included in the breeding goal, but consistent with the previous three challenge tests. This low heritability is also consistent with field data that the breeding company has been collecting and indicates that the phenotype collected in the challenge test is robust and reliable.
Since lesions without mortality is not possible, the endpoint of this challenge will inevitably be mortality. A genome-wide association analysis revealed no significant regions of the genome that are linked to resistance, suggesting that this trait is polygenic and genomic selection is the best way forward to ensure progress for this trait.
Up to 1500 animals were applied for and approved used in the experiment. In total 1487 salmon were used. 502 salmon were classified as mildly harmed and 985 were classified as severely harmed. This was 185 salmon more than expected 800 with this severity. This was due to an unexpected high mortality the infection trial. If surviving salmon had wounds scored 2 or 3, we assess that these animals should be classified as moderately harmed.