DENMARK - Rainbow trout and other farmed fish can be produced with a lower consumption of antibiotics if the vaccination strategy is optimized. This would benefit the fish as well as the environment.
Scientists would like to improve fish health and reduce the consumption of antibiotics in Danish aquaculture. This is the purpose of a new research and development project managed by Aarhus University and Dansk Akvakultur (Danish Aquaculture).
In this project scientists and industrial partners are collaborating to develop new and improved vaccination strategies.
The project results will help to reduce aquaculture’s consumption of antibiotics, reduce the environmental impact, increase fish welfare and improve the fish producers’ economy. This improved sustainability in aquaculture can be achieved by developing vaccines and vaccination strategies specifically adjusted to Danish aquaculture conditions.
Aquaculture is expanding
Fish is a healthy and popular food choice as its excellent fat composition reduces the risk of cardiovascular diseases. However, the wild fish population is under pressure as a result of overfishing and climate changes, among other factors. There is therefore an increased focus on production of fish in aquaculture. This is also the case in Denmark, which has a political goal of increasing the Danish production of aquaculture by 25 per cent by 2020.
Denmark has significant potential for developing its aquaculture production in which rainbow trout is an important product. Implementation of new technologies allows for an expansion of production without increasing the environmental impact. One of the means is an optimized strategy for vaccines and vaccination for prophylaxis of disease outbreaks.
Ensuring healthy fish
Like all other animals fish can catch various diseases. The fish are therefore vaccinated and, if necessary, treated with antibiotics against infectious diseases.
In theDanish production of rainbow trout, bacterial diseases such as redmouth disease, vibriosis and furunculosis are especially problematic. As a preventive measure the fish are vaccinated against these diseases, but the vaccines are not always efficient under Danish conditions. This can lead to disease outbreaks, which require antibiotic treatment of the fish.
The use of antibiotics can result in the development of resistant bacteria in the environment. In addition, the mortality and reduced growth during disease and treatment will impair fish welfare as well as production profitability.
"The vaccines used in Danish aquaculture production are based on foreign variants of the pathogenic bacteria. This might explain why the vaccines are not always efficient under Danish conditions, where bacterial variants as well as fish growth conditions differ from those of our neighbouring countries," explains Professor Niels Lorenzen from the Department of Animal Science at Aarhus University.
Custom-made vaccines for Danish conditions
The project will develop new vaccines based on Danish variants of the relevant bacteria and also takelocal variations into account.
In aquaculture both injection vaccination and dip vaccination is used. Vaccines that are injected usually consist of a water-oil emulsion. Some oil types have undesirable side effects in the form of inflammation and autoimmune reactions. Part of the project efforts will be dedicated to identifying the optimum vaccine formulation that provides excellent protection with a minimal degree of side effects. This will improve animal welfare as well as the quality of the final product.
The project focuses on initial development and testing of vaccines in experimental laboratory scale and subsequent documentation of the effect at commercial fish farms in order to facilitate industrial implementation of the results. .
The project title is VAXFISK and the Danish Ministry of Environment and Food, Green Development and Demonstration Programme (GUDP), has granted DKK 12.1 million to the project.
Project partners include Aarhus University, Dansk Akvakultur (Danish Aquaculture), University of Copenhagen, the Technical University of Denmark, AquaPri, veterinary practitioner Simon B. Madsen and Aquabaltic.
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