Understanding morphological rib abnormalities in Atlantic salmon

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The effect of vaccine-associated cross-stitch vertebrae pathology on growth of farmed Atlantic salmon

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Validation and genetic parameters of the X-ray method for phenotyping individual feed intake in Atlantic salmon

Feed efficiency is a highly desirable breeding goal trait as it can potentially reduce the relative economic cost of feed and concurrently reduce the environmental footprint of fish production. However, recording feed intake is a bottleneck in Atlantic salmon production. We recorded feed intake in 700 Atlantic salmon parr from 34 full sibling families using the X-ray method, where fish were fed feed containing radio-opaque beads and subsequently X-ray imaged one time after a full meal corresponding to the daily ration. In parallel, we cultured siblings from the same 35 families in duplicate family tanks of 25 individuals per tank and recorded the daily feed intake of each family at the tank level, which is known as the gold standard tank-based method. The heritability estimate for daily feed intake in Atlantic salmon using the X-ray method was significantly different from zero (0.19 ± 0.06) and was genetically correlated to growth-related traits (rg = 0.48–0.81). Daily feed intake at the family level with the X-ray method was highly genetically correlated to the daily feed intake traits using the tank-based feeding method at 0.78–0.82, depending on whether the comparison was made at a common time, common weight, or cumulative feed intake for the entire period. Whilst the X-ray method holds promise for research on the genetic background of feed intake and feed efficiency, more studies are needed to investigate the feasibility during the sea phase of Atlantic salmon production.publishedVersio

Rib abnormalities and their association with focal dark spots in Atlantic salmon fillets

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Ossification of Atlantic cod (Gadus morhua) – Developmental stages revisited

In studies of marine larvae, it is common to use days post-hatch as a developmental reference point. We show that age is a poor measure of morphological and physiological development in Atlantic cod. Therefore, we propose a set of five developmental stages of Atlantic cod fromstart-feeding until the juvenile stage, based on cranial ossification as previously done in Atlantic halibut. Cod follows a sequence of cranial ossification that is to a large extent preserved in most fish species examined. These stages are therefore tools to standardize sampling and to reduce growth dependent variation in the analysis of larvae during development. Weshow that several developmental stages are present in the same rearing unit at a given time. We also demonstrate that nutrition during early development is a vital foundation for robust skeletal development. Cod larvae supplied with copepods instead of rotifers followed by Artemia, develop less skeletal deformities at 10 cm standard length, despite given the same formulated feed from 1.8 cm standard length and onwards. Statement of relevance: This paper provides developmental stages that are vital for best practice protocols in aquaculture. By relating farming practices to developmental stages and not age, the right treatment ect may be provided. This manuscript does also highlight the importance of nutrition during live feed stages on events that may occur late in the production cycle.acceptedVersio

Long-term feeding of Atlantic salmon with varying levels of dietary EPA+DHA alters the mineral status, but does not affect the stress responses after mechanical delousing stress

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Digital phenotyping of individual feed intake in Atlantic salmon (Salmo salar) with the X-ray method and image analysis

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Mineral nutrition and bone health in salmonids

In the recent years, challenges faced in salmonid farming with regard to deformities have helped to improve our knowledge on skeletal biology and development of bone health in salmonids. Different nutritional, genetic and environmental factors are associated with skeletal deformities in salmonids and other fish species. Minerals are a group of essential nutrients having a vital role to play in skeletal development, growth and remodelling. The knowledge generated thus far on the structural and functional importance of minerals in salmonid bone health is largely restricted to phosphorus. A brief account of dietary phosphorus‐related bone deformities encountered in salmonids, critical life stages for the development of bone deformities, recent developments in the understanding of their aetiology and dietary phosphorus levels required to improve bone health are presented. The effect of increased dietary level of phosphorus in reducing bone health disorders under conditions of improved feed conversion efficiency and use of triploids in salmon farming are illustrated with help of metadata analysis from literature. With regard to the role of other essential minerals (macro‐ and micro‐) impacting bone health in salmonids, data available are extremely limited and hence information on other fish species and mammals is summarized in relation to bone development and incidence of deformities. The need to improve mineral bioavailability, utilization and reduce effluent mineral load is presented in brief with example from Norwegian salmon farming. Refinements in mineral requirement recommendations for salmonids and advanced methodologies for studying aetiology of skeletal anomalies, bone mineral status, skeletal development and deformities are also discussed.publishedVersio

Long-term feeding of Atlantic salmon with varying levels of dietary EPA þ DHA alters the mineral status but does not affect the stressresponses after mechanical delousing stress

Atlantic salmon were fed diets containing graded levels of EPA + DHA (1·0, 1·3, 1·6 and 3·5 % in the diet) and one diet with 1·3 % of EPA + DHA with reduced total fat content. Fish were reared in sea cages from about 275 g until harvest size (about 5 kg) and were subjected to delousing procedure (about 2·5 kg), with sampling pre-, 1 h and 24 h post-stress. Delousing stress affected plasma cortisol and hepatic mRNA expression of genes involved in oxidative stress and immune response, but with no dietary effects. Increasing EPA þ DHA levels in the diet increased the trace mineral levels in plasma and liver during mechanical delousing stress period and whole body at harvest size. The liver Se, Zn, Fe, Cu, and Mn and plasma Se levels were increased in fish fed a diet high in EPA þ DHA (3·5 %) upon delousing stress. Furthermore, increased dietary EPA þ DHA caused a significant increase in mRNA expression of hepcidin antimicrobial peptide (HAMP), which is concurrent with downregulated transferrin receptor (TFR) expression levels. High dietary EPA + DHA also significantly increased the whole-body Zn, Se, and Mn levels at harvest size fish. Additionally, the plasma and whole-body Zn status increased, respectively, during stress and at harvest size in fish fed reduced-fat diet with less EPA + DHA. As the dietary upper limits of Zn and Se are legally added to the feeds and play important roles in maintaining fish health, knowledge on how the dietary fatty acid composition and lipid level affect body stores of these minerals is crucial for the aquaculture industry

Betydning av tidspunkt og lengde av vintersignal i RAS for prestasjon i sjø ved utsett av stor smolt

Source at https://nofima.no/.Under kontrollerte forhold i kar var det en positiv effekt av et vintersignal kombinert med brakkvann i RAS på vekst etter overføring til sjøvann. Men et vintersignal ga også økt kjønnsmodning i hannfisk når fisken gikk lenge i RAS på kontinuerlig lys etter at vintersignalet var avsluttet. Kjønnsmodning ble redusert når fisken ble satt ut på lav sjøtemperatur. Resultatene fra utsett i sjømerder viste betydelig høyere dødelighet som følge av vintersår og lavere vekst i sjøfase hos stor smolt på henholdsvis 320 og 850 g satt ut i oktober og januar sammenlignet med fisk satt ut i september ved 160 g. Resultatene fra kar med sjøvann viste ikke store forskjeller i TGC mellom de ulike utsettene, og fisk overført på 320 g hadde høyest TGC i kar. Dødelighet i kar med sjøvann var lav, henholdsvis 0, 0,2 og 1,1 % for de tre utsettene. Forsøket i kar med sjøvann viste at den større smolten har et potensial for god vekst i sjøvann, men også høyere risiko for kjønnsmodning, særlig på høy temperatur i sjøfase. Årsaken til at den større smolten var mer sensitiv mot vintersår og hadde høyere dødelighet i merder i sjø enn mindre fisk som hadde gått lenger i sjø før utbruddet startet bør undersøkes nærmere