Use of functional feeding strategies to protect Atlantic salmon from virally-induced inflammatory diseases- mechanistic insights revealed by transcriptomic analysis

Over the past few years one of the major concerns in the Atlantic salmon (Salmo salar) farming industry has been the increasing incidence and severity of inflammatory viral diseases. Heart and skeletal muscle inflammation (HSMI) and cardiomyopathy syndrome (CMS) are currently two of the most prevalent viral diseases in commercial Atlantic salmon farms in Norway. Mortality levels in both diseases are generally low but morbidity can be very high with the associated chronic inflammatory response lasting for several months. The consequent reduced growth performance is causing considerable financial impact as HSMI has become increasingly widespread in recent years. The impact of CMS is further exacerbated as it generally affects large fish close to harvest. HSMI lesions occur in the atrium and ventricle in the heart including inflammation and necrosis in epi- endo- and myocardium along with myositis of red skeletal muscle. CMS lesions are commonly observed in the spongy myocardium in the atrium and ventricle of the heart with severe mononuclear inflammation and necrosis. Furthermore, circulatory disturbances associated with reduced cardiac function cause multifocal liver steatosis and necrosis in both diseases. Currently there are no vaccines or any other effective treatments for these diseases and so alternative therapies that could potentially modulate the intensity of the inflammatory response could be crucial to improve the clinical manifestation of the diseases. Therefore, the overall aim of the present study was to evaluate the concept of “clinical nutrition” to improve the clinical symptoms of both viral diseases, HSMI and CMS, through the use of functional feeds formulated with reduced lipid content and increased proportions of anti-inflammatory fatty acids to moderate the apparently uncontrolled inflammatory response in the heart tissue associated with both diseases and also alleviate the secondary hepatic lesions. The experimental work consisted of three major dietary trials in Atlantic salmon in seawater. Two large trials investigated the effects of functional feeds in Atlantic salmon challenged with Atlantic salmon piscine reovirus (ASRV) and piscine myocarditis virus (PMCV), the causal agents of HSMI and CMS, respectively. In both trials, heart transcriptome, heart and liver histopathology and tissue lipid and fatty acid compositions and metabolism were determined post-infection in fish fed with the functional feeds in comparison with fish fed with a standard commercial feed formulation considered as a reference diet. All the functional feeds were formulated to have reduced digestible energy through lower dietary lipid and higher protein contents, and increased levels and proportions of anti-inflammatory long-chain polyunsaturated fatty acids (LC-PUFA), particularly eicosapentaenoic acid (EPA) compared with the reference diets. Histopathology, fatty acid composition and gene expression of heart were assessed over a long time-period of 16 weeks and 14 weeks post-challenge with ASRV and PMCV, respectively. Viral load in heart tissue, hepatic histopathology and fatty acid composition of liver and head kidney along with expression of the genes involved in the eicosanoid and LC-PUFA and eicosanoid biosynthesis pathways were also determined in the HSMI trial. The third trial was a nutritional trial evaluating the effects of dietary digestible energy content on lipid and fatty acid metabolism in salmon fed diets containing graded amounts of lipid. Fatty acid composition of liver and heart were assessed over 12 weeks, along with the hepatic expression of genes of lipid and fatty acid metabolism. The results of this research are presented in four chapters (Chapters 2-5) as four paper manuscripts. The manuscripts/Papers are either published (Chapter 2), in review (Chapter 3 and 4) or drafted for submission (Chapter 5) in appropriate peer-reviewed international journals. Chapter 2 and 3 correspond to the HSMI trial, Chapter 4 to the nutritional trial, and Chapter 5 to the CMS trial. Chapter 2 showed that viral load and histopathology scores were lower in fish fed the functional feeds, especially diet FF1, which displayed better performance. Diet strongly influenced the expression of genes related with the immune and inflammatory responses, with delayed expression in fish fed the functional feeds. Up-regulation of pro-inflammatory genes was correlated with the higher viral load observed at early-mid stages of the disease in fish fed the reference diet (ST). Expression of genes related with the immune response at 16-weeks post challenge reflected the differences in immunomodulation between the functional feeds, with fish fed diet FF1 showing lower expression. Therefore, severity of the heart lesions was correlated with the intensity of the immune response and could be associated with tissue anti-inflammatory LC-PUFA levels. Chapter 3 was focused on liver histopathology, fatty acid composition and LC-PUFA biosynthesis, along with phospholipid fatty acid composition and eicosanoid production in head kidney and heart tissue at early and late stages of ASRV infection. Liver was severely affected by the virus at the beginning of the infection in fish fed the reference ST diet, but the level of lesions were similar in all dietary groups at the end of the trial. Hepatic expression of fatty acyl desaturases was significantly depressed in fish fed the ST diet compare with fish fed the functional feeds despite the lower levels of dietary LC-PUFA in that feed. Thus endogenous production and bioavailability of anti-inflammatory LC-PUFA was potentially enhanced in fish fed the functional feeds. Changes in tissue lipid content, mobilization of fatty acids involved in inflammatory responses and changes in expression of transcription factors and genes involved in eicosanoid biosynthesis were more prominent in head kidney, confirming the important role of this organ in dietary immunomodulation after viral infection. To a lesser extent similar changes were observed in heart tissue, suggesting in situ production of eicosanoids could also be important. The unexpected effects of diet on expression of genes of LC-PUFA biosynthesis were specifically investigated in the trial described in Chapter 4. One aim of this study was to clarify whether dietary lipid content or viral infection was the cause of altered expression of desaturase genes between the different diets. Hepatic expression of other genes of lipid and fatty acid metabolism were also determined to evaluate metabolic changes associated with dietary lipid/energy level. In general, reduction of dietary energy and lipid contents while maintaining similar proportions of dietary fatty acids, led to a general up-regulation of genes involved in lipid biosynthetic pathways. Thus salmon fed lower energy diet showed increased liver expression of fatty acyl desaturases in comparison with fish fed higher energy levels. Heart transcriptomic data in Chapter 5 showed a similar delay in the inflammatory response in fish fed the functional feeds after PCMV infection as observed in the HSMI study. Modulation of inflammatory responses, similar to that previously described after ASRV infection, was also observed in fish fed the functional feeds. However, the differences in the expression of immune related genes and the level of heart lesions were not as prominent at mid-late stages of the disease as in fish fed FF1 in the HSMI trial. The present study demonstrated the beneficial effects of a clinical nutrition approach via functional feeds in two viral inflammatory diseases, HSMI and CMS, currently affecting farmed Atlantic salmon. Dietary immunomodulation increased the availability of anti-inflammatory LC-PUFA and significantly influenced the expression of the genes related with the immune/inflammatory response reducing the level and severity of cardiac and liver lesions and therefore improving the performance of fish suffering the diseases

Kystsoneplan for Sunnhordaland. Regionalplan for akvakultur Del 3: Konkurrerende bruker- og verneinteresser

Rapporten presenterer de viktigste bruker- og verneinteresser i kystsonen i Sunnhordaland. Hensikten er å gi en regional oversikt over aktivitetene i kystsonen som kan benyttes som et underlag for å vurdere i hvor stor grad det er konkurranse om ressurser og lokaliteter mellom akvakultur og andre interesser. Det er foretatt en analyse av konfliktpotensiale i 188 lokaliteter i regionen som er vurdert som egnet for mæroppdrett i sjø. Det er også gitt en vurdering av konfliktene i vassdrag når det gjelder settefiskproduksjon

Kystsoneplan for Sunnhordaland. Regional plan for akvakultur. Del 1: Metoder for kartlegging av arealbruksinteresser og ressurser i Sunnhordaland

Kystsoneplan for Sunnhordaland er et ressursregistrerings- og utrednings-/planprosjekt spesielt rettet mot akvakultursektoren. Det har også vært et mål å kartlegge flest mulig andre brukerinteresser for å kunne foreta en samordnings- og konfliktvurdering. I utgangspunktet var både metode- og datagrunnlag svært mangelfullt. Et viktig mål innen prosjektet har vært å velge ut, videreutvikle og eventuelt finne fram til nye metoder for innsamling og analyse av relevante data til bruk i kommunal og regional kystsoneplanlegging. Denne rapporten gir en samlet oversikt over sentrale metoder og kriteriesett som er nyttet

User experience with on-line predictive river flow regulation

A control strategy based on adaptive prediction and a receding horizon controller is used to regulate the river flow-rate in Suldalslågen in the Ulla-Førre production system on the south-west coast of Norway. The adaptive prediction of the unregulated inflow used precipitation data and flow-rate data from a stream in the catchment area. In addition, a recursive estimation algorithm is used to estimate the stationary gains of the parallel transfer function models which have the catchment area data as input and the unregulated inflow as output

The Norwegian Healthier Goats programme - A financial cost-benefit analysis

The aim of this study was to evaluate the profitability to dairy goat farmers of participating in the Healthier Goats disease control and eradication programme (HG), which was initiated in 2001 and is still running. HG includes the control and eradication of caprine arthritisencephalitis (CAE), caseous lymphadenitis (CLA) and paratuberculosis (Johne's disease) in Norwegian goat herds. The profitability of participation was estimated in a financial cost-benefit analysis (CBA)using partial budgeting to quantify the economic consequences of infectious disease control through HG versus taking no action. Historical data were collected from 24 enrolled dairy goat herds and 21 herds not enrolled in HG, and supplemented with information from a questionnaire distributed to the same farmers. Expert opinions were collected to arrive at the best possible estimates. For some input parameters there were uncertainty due to imperfect knowledge, thus these parameters were modelled as PERT probability distributions and a stochastic simulation model was built. The CBA model was used to generate distributions of net present value (NPV) of farmers' net cash flows for choosing to enroll versus not enrolling. This was done for three selected milk quota levels of 30 000 L, 50 000 L and 70 000 L, and both for before and after the introduction of a reduced milk price for the non-enrolled. The NPVs were calculated over time horizons of 5, 10 and 20 years using an inflation-adjusted discount rate of 2.8% per annum. The results show that participation in HG on average was profitable over a time horizon of 10 years or longer for quota levels of 50 000 L and 70 000 L, although not without risk of having a negative NPV. If farmers had to pay all the costs themselves, participation in HG would have been profitable only for a time horizon beyond 20 years. In 2012, a reduced milk price was introduced for farmers not enrolled in HG, changing the decision criteria for farmers, and thus, the CBA. When the analysis was altered to account for these changes, the expected NPV was positive over five years for the 50 000 L quota, indicating an increased profitability of enrolling in HG. The sensitivity analysis showed that particular attention should be paid to work load and investment costs when planning for disease control programmes in the future

A comparison of European surveillance programs for campylobacter in broilers

Campylobacter is an important foodborne pathogen as it is associated with significant disease burden across Europe. Among various sources, Campylobacter infections in humans are often related to the consumption of undercooked poultry meat or improper handling of poultry meat. Many European countries have implemented measures to reduce human exposure to Campylobacter from broiler meat. In this paper, surveillance programs implemented in some European countries is summarized. Our findings reveal that many European countries test neck skin samples for Campylobacter as per the Process Hygiene Criterion (PHC) set by the European Regulation. Variations to the legal plan are seen in some countries, as in Norway and Iceland, where weekly sampling is performed during infection peak periods only, or in Iceland, where the Campylobacter limit is set at 500 CFU/g instead of 1000 CFU/g. Furthermore, northern European countries have implemented national Campylobacter surveillance plans. Denmark tests cloaca and leg skin samples at the slaughterhouses and meat samples at the retail, while Finland, Norway, and Sweden test caeca at slaughterhouses. In contrast, Iceland tests feces on farms. Iceland and Norway test flocks close to the slaughter date and when a farm tests positive, competent authority implement measures such as logistic slaughter, heat treatment or freeze the meat from these flocks. In Iceland, frozen meat is further processed prior to being put on the market. While the incidence of campylobacteriosis has declined in all European countries except France since the introduction of PHC in 2018, it is uncertain whether this decrease is due to prevalence reduction or underreporting during the COVID-19 pandemic. Future investigations with more comprehensive data, devoid of potential confounding factors, are necessary to validate this potential trend. However, it is evident that the implementation of national action plans can be successful in reducing the incidence of human campylobacteriosis, as demonstrated by Iceland