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The international company Skretting introduced in Norway Nutra Terra, a novelty in hatchery feed with documented good performance and reduced emissions. According to them, trials have shown up to a 30 per cent reduction in the release of phosphorus and zinc from faeces, at the same time fish fed Nutra Terra have significantly better growth and a lower feed factor, they assured.
“In validation trials, we have seen a 7 percent increase in growth and a 4 percent lower feed factor with Nutra Terra. It is gratifying to see such good performance figures at the same time as we are reducing the need for limited raw materials,” explain Marcus Søyland, head of land-based operations at Skretting Norway.
For the company, Nutra Terra represents Skretting‘s biggest innovation in growth feed for hatchery fish in over a decade. All available knowledge and research have been brought together to develop a new and optimized feed recipe. The result is a feed that gives better performance, while emissions from the fish are reduced and the raw materials in the feed are used better.
Reducing the need for limited raw materials
Skretting believes that the key to success lies in raw materials. Nutra Terra contains smaller amounts of limited raw materials such as fishmeal and phosphorus compared to conventional hatchery feed. Part of the fishmeal has been replaced with insect protein, which is part of the salmon’s diet in nature at this stage of life.
Experiments shown that the fish absorb more phosphorus and the same amount of zinc with Nutra Terra, despite the fact that the feed contains less of these minerals. A pleasant effect of this is that less phosphorus and zinc are excreted in faeces.
One of the major changes in the recipe
Increased use of new feed raw materials and optimization of existing raw materials will help to ensure sustainable growth in the aquaculture industry. One of the major changes in the feed recipe for Nutra Terra is the enzyme phytase, which makes phosphorus and zinc in plant raw materials more available to the fish. This makes it possible to reduce the total amount of phosphorus and zinc added to the feed.
“Experiments show that the fish absorb more phosphorus and the same amount of zinc with Nutra Terra, despite the fact that the feed contains less of these minerals. A pleasant effect of this is that less phosphorus and zinc are excreted in faeces. In trials, we have seen that fish fed Nutra Terra have 30% lower emissions of phosphorus and zinc,” Søyland shows.
In addition, deformities are a well-known challenge in the aquaculture industry, and phosphorus plays an important role in the development of the fish’s skeleton.
“In trials with Nutra Terra, we have analyzed the spine of the fish to look at mineralization and deformities. The results show that fish fed with Nutra Terra accumulate more phosphorus in the spine, which is positive for the fish’s bone development,” explains the specialist.
New and more valuable areas of use for the sludge
The sludge from hatcheries can potentially be used for the production of fertilizer. In order for sludge to be used as fertilizer, it must meet the quality criteria set in the Fertilizer Regulations. The amount of zinc is decisive for the grading of the sludge. In trials, it has been documented that fish fed with Nutra Terra utilize zinc more efficiently, and the amount of zinc in faeces is reduced.
“Reduced zinc emissions open up new and more valuable areas of use for the sludge from land-based facilities. In some fjords, phosphorus emissions can limit production, and the reduction in phosphorus emissions can give our customers new opportunities for increased production”, concluded Marcus Søyland.
