UK project explores benefits for salmon when fed hemp seed protein

The move follows the success of feasibility trials last year.

Rare Earth Global, the company behind the initiative and growers of industrial hemp for a range of sustainable products, has received more than £260,000 (US$329K) in funding from the UK Seafood Innovation Fund (SIF) for a full-scale research and development project which will include a two-month feed assessment.

The next stage of testing involves monitoring how fish perform over the long term when fed hemp seed protein as part of their diet, with the company also supported by the Sustainable Aquaculture Innovation Centre (SAIC) and the University of Stirling’s Institute of Aquaculture.

Mowi, the global Atlantic salmon producer, will support the formulation and production of the feed, while farmers in Angus and Aberdeenshire will grow the crops.

Hemp-based protein is already used in cattle and poultry farming. Hemp fiber is also used to produce paper and textiles. 

The researchers are hoping to get protein levels in the hemp seed meal of over 50%.

Feasibility study​

The feasibility study conducted last year set out to explore how hemp seeds could be integrated into the diets of farmed salmon in Scotland. The team evaluated two types of hemp meal against a range of factors such as digestibility, fish growth, and the effect on gut health.

The first step was to fully characterize ​​several products. The researchers saw that hempseed meals include high levels of aspartic acid, glutamic acid, phenylalanine, histidine, and arginine comparable to levels in fish meal. The methionine content is around half that of fish meal, similar to the levels of that amino acid in soy protein concentrate (SPC).

Minimum levels of antinutritional factors were found in the meals. The two hempseed meals with the highest protein content (42% and 46%) were used at a 30% inclusion level in digestibility assessments and benchmarked against a highly digestible feed. After two weeks, feces were obtained and digestibility of the two tested hempseed meal calculated. Both meals proved to be highly digestible, with an overall protein digestibility of the ingredients of 100%, said the team.

The good digestibility of the test ingredients was also corroborated by in vivo digestibility, using an artificial salmon gut (SalmoSim).

"This was only a small scale lab feasibility trial. The trials taking place this year and next will give us greater amount of data so we can have definitive results," said a spokesperson for Rare Earth Global.

Raw material supply​

The project’s zero-waste approach to growing the hemp ensures that every part of the plant is used for maximum value. In this case, the seeds will be used as a protein source for aquaculture, while the stalks will be used for sustainable construction materials, bioplastics and bioenergy feedstocks.

Up to two tons of hemp seed can be produced per hectare of the crop, and Rare Earth Global is working with a range of farming cooperatives and family run farms – including farmers in Scotland, Yorkshire, Lincolnshire, and Hertfordshire – to develop the supply of the raw material throughout the UK.

"We are receiving more and more inbound customer enquiries for our protein concentrate. Our first milestone is to reach 5,000 hectares. Our model is based on sub-contracting and managing/supporting farming groups," the spokesperson told this publication. 

In terms of incentives for farmers to get involved in the project, the representative said: "As farming subsidies have been pulled, we are introducing a new rotation crop that can provide a stable income and good return for farmers over the long term. Additional benefits, include improved soil structure, zero pesticides and carbon credits in the near term."

Carbon footprint

The team will also look to identify methods for hemp farmers, feed companies and seafood producers to measure the carbon footprint of the entire process.

Last summer, the UK government published its Hemp-30 roadmap​​ – a 10-year strategy to make industrial hemp a major UK crop. It is estimated to add around £700m to the economy and sequester or displace 1m tons of carbon dioxide each year.

Commenting on the project, Sarah Riddle, director of innovation and engagement at SAIC, said: “There are opportunities here for new UK-based supply chains to emerge, reducing our reliance on imported ingredients and lessening the overall environmental footprint of aquaculture while increasing its economic contribution.”