Mattrygghet: Healthy feed to healthy aquatic food via Sino-Norwegian cooperation (Feed2food)

During 2022, the Feed2Food project partners in Norway and China have tried to carry out the project tasks in line with pandemic restrictions in both countries. All the project partners have had regular contact with CAAS and NTNU during 2022 via e-mail, Teams and Zoom meetings, and social media. Salmon trials were carried out at NTNU's experimental facility in spring 2022 with fish feed supplemented with propionate in various doses and with high- or low-fat ingredients. Results have been partially published. Test samples that NTNU took and delivered to NIBIO have been sequenced and bioinformatic analyses are ongoing. New scripts based on bioinformatic analyses and other analyses are being worked on. In addition to collaboration on project tasks, NTNU, NIBIO and CAAS have collaborated on educating MSc and PhD students. Two PhD students completed their studies in good cooperation between CAAS and NTNU and received their doctorates in Nov 2022. Several joint publications were produced between partners (see list). Postdoc training has also become an important activity that the project partners have collaborated on and carried out. Fish trials that CAAS, NTNU and NIBIO were supposed to carry out together in Beijing have been delayed due to travel restrictions, but the trial has been fully planned and will be carried out in the spring of 2023. Rainbow trout (Oncorhynchus mykiss), a predatory fish in the salmon family that originally originates from North America, will be grown in the experiment at CAAS in Beijing, which has facilities for fish experiments on various scales. NIBIO's postdoc will go to CAAS to actively participate in the fish trial in spring 2023 when the trip is possible. A salmon cell line platform for testing various probiotics and other fish feed ingredients that are important for sustainable fish feed was established at NIBIO in 2022 and will be used for the testing of probiotics and candidate fish feed in 2023 and 2024 in collaboration between all parties (CAAS, NIBIO and NTNU). Probiotics can strengthen fish immune defenses and reduce the consumption of antibiotics in aquaculture, at a time when antimicrobial resistance (AMR) has become a global problem for humans, animals and the environment (“One Health”). Although 2022 has been characterized by the pandemic, the Feed2Food partners in China and Norway have carried out all the tasks that could be carried out. Some tasks have been delayed, but will be carried out next year and in 2024. We have therefore applied for a project extension to 31 December 2024 without additional funding, but with more time to carry out the tasks and deliver the results. The progress plan, milestones and budget have been changed online in connection with the project extension.

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The project is at the forefront of scientific research in utilizing molecular, physiological and high advanced methodology to quantify the challenges with feed additives in combination with high fat diets (HFD). As a representative of this challenge, we recently found that sodium propionate (SP), a widely used antifungal additive, induced intestinal injury in zebrafish under high fat diet conditions. This may impair intestinal barrier to an extent leading to microbial and lipopolysaccharide (LPS) translocation over the intestine. We will therefore identify the molecular mechanisms behind the damaging effect of SP. One line of research will focus on protein propionylation of essential enzymes as indicated as one possible causative mechanism. The project will then progress into monitoring possible translocation of intestinal bacteria, virus and LPS into systemic circulation and edible tissues with possible secondary biological hazards that can pose a health challenge for both fish and the consumer. The mechanistic studies will mainly use zebrafish and mouse as well as microbiota-depleted or germ-free animal models, while tilapia and Atlantic salmon will be used to confirm phenotypes in economic important fish species. Finally, the project will screen probiotic bacteria and their chemical compounds for their ability to up-regulate intestinal barrier function which may provide possible solutions for such safety issues.