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EXPERT TOPIC RAINBOW TROUT

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FEEDING THE PIONEER

Rainbow trout, Oncorhynchus mykiss ŠAller Aqua

Rainbow trout’s contribution to aqua feed development by Dr Hanno Slawski, Group R&D Director, Aller Aqua

ainbow trout are rovers. Their braveness to explore new habitats and their adaptability to various environments has made trout a perfect species for aquaculture. The trout as a pioneering species in the sector has also paved the way for other fish species in terms of nutritional requirements, feed manufacturing, farming systems and certifications. The knowledge obtained through research on trout has led to a comprehensive understanding of nutritional and physical feed quality as well as raw material quality and its impact on nutrient digestibility, feed palatability and faeces quality. As far as applicable, the knowledge obtained in research on trout has also been introduced into feeds for other species.

can digest. Thus, a stable content of digestible protein and energy in the feed is more relevant than the total content of protein and energy in the feed or the selection of raw materials. Providing the optimum combination of digestible protein and digestible energy is paramount for growth performance of fish. Formulating feeds according to fixed levels of digestible protein and energy outbalances varying numbers of total protein and total energy in a raw material. Furthermore, formulating feeds according to nutrient digestibility is the closest one can do to stabilise feed

Raw material nutrient digestibility

In recent years, feed for rainbow trout has undergone major changes in raw material selection and composition. Institutional and industrial research has led to an understanding of the nutritional requirements of trout that is only matched in a few other fish species. As one example, it was possible to reduce the dependency on marine raw materials in feed formulations, which used to be the reference for nutritional quality. However, raw materials provide nutrients to a feed. But not all nutrients from a raw material are accessible for fish. This also counts for fishmeal and fish oil. Some raw materials contain less accessible nutrients. Accessible nutrients can also be described as digestible nutrients. Digestible nutrients are the nutrients that are absorbed by fish from a feed between feed intake and faeces excretion. Thus, digestible nutrients are ingested nutrients minus nutrients excreted via faeces. Consequently, the nutrients having value for fish are the ones it

Feeding trout in Aller Aqua Research Š Aller Aqua

30 | August 2017 - International Aquafeed

Aug 2017 - International Aquafeed magazine  
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