New case study: using nettle as a feed ingredient for health and performance in Atlantic Salmon
Testing whether nettle could be added to feed to benefit Atlantic salmon
As salmon farming grows, producers look for new natural feed additives that can improve fish health and performance. Many current ‘functional feeds’ use prebiotics and probiotics and there there is increasing interest in broadening the range of effective, sustainable components.
The common nettle (Urtica dioica) has long been recognised for its health‑boosting properties in farmed animals. It contains natural compounds with potential anti‑inflammatory and antioxidant effects, and may act as a prebiotic by influencing gut microbes and nutrient uptake.
The University of Aberdeen led this project to test whether nettle could benefit Atlantic salmon. The other partners were BioMar UK, Scottish Sea Farms, Urtica Plus, and the University of the West of Scotland. The project was valued at over £210k.
Feed company BioMar produced three diets for a trial: a commercial control diet, and diets containing 1% and 3% nettle. Throughout the trial, all groups showed similar growth, condition and feed conversion. A technical issue affecting the trial briefly showed that salmon on the 1% nettle diet appeared more resilient, but by the final sampling all fish reached comparable weights.
Gut health was important, as salmon can react negatively to some plant ingredients. Examination of the intestine showed all fish had healthy gut tissue and the study concluded that nettle levels up to 3% were tolerated, with no signs of inflammation.
Blood chemistry also showed no negative effects. Some markers hinted at small potential health benefits, but these trends were not strong enough to be considered significant. To test immune resilience, unvaccinated fish were challenged with a bacterial pathogen. Survival was slightly higher in fish fed the nettle diets - particularly the 3% group - but again results were not statistically significant.
This first experimental use of nettle in salmon feed shows that up to 3% inclusion is safe and performs as well as standard commercial diets. Although early signs suggest small potential benefits, especially at around 1% inclusion, none were large enough to provide confirmation. Further research, including refining nettle extracts to isolate useful bioactive compounds, is needed to determine whether nettle could offer meaningful commercial advantages for salmon producers.
The full title of this project is ‘Novel functional feeds for improved performance in Atlantic salmon based on nettle’
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