News Environment, Fish

Through selective breeding, it is possible to prevent excessive lipid deposition in rainbow trout, which improves not only the feed conversion ratio, but also the efficiency of protein retention. Both are important from the economic perspective.

The results of the FISHBOOST project show that it is possible to improve feed conversion ratio in rainbow trout through selective breeding. By favouring rapid growth and restricted lipid deposition, it is possible to enhance the genetic improvement of the feed conversion ratio by 30 per cent, compared to favouring just growth.

An improved feed conversion ratio means that the same amount of feed yields more fish and, hence, more income. Fish material that utilizes feed more efficiently also benefits the environment, when an increasing share of feed nutrients is bound to the fish instead of ending up in waters.

Restricting lipid deposition through selective breeding also improves the efficiency of protein retention, albeit slowly. It is important for the fish to use the expensive feed proteins in muscle growth and not in energy production. The carbohydrates and lipids contained in feed should be the primary source of energy for the fish. The results of the project indicate that a genetically efficient, rapidly growing fish with no excessive lipid deposition converses the protein in feed more efficiently to muscle growth instead of storing the protein as lipids. This is also the goal of the selection programme, where growth and lipids are targeted simultaneously.

By limiting the lipid deposition of the fish, the food quality of the fish is also improved, while the amount of processing waste from fish is reduced.

Even a small improvement in genetic fish material has a major impact on aquaculture industry

The Natural Resources Institute Finland (Luke) maintains the JALO selection programmes for rainbow trout and European whitefish for the benefit of the aquaculture industry. Around 80 per cent of all rainbow trout farmed in Finland has ancestries in the selection programme. For this reason, even a small genetic improvement in the fish material has a major impact on the industry.

The principles of selective breeding are presented in the following video by the FISHBOOST project

Until now, the rainbow trout feed conversion ratio has been boosted by selecting for rapid growth. As a result of selecting growth for eight generations, the feed conversion ratio has already improved by several dozen percentage points. Such improvement means that the same amount of feed yields between 15 and 20 per cent more fish and more income. It also helps to improve the international competitiveness of the industry.

– Assuming that the production volume in Finland of rainbow trout improved through selection is around 10 million kilos, the feed conversion ratio is 1.1 and the price of feed is EUR 1.25 per kilo, it means that a 20 per cent reduction in feed costs translates into an annual saving of EUR 2.75 million, explains Antti Kause, Principal Researcher at Luke.