Study on the use of grass proteins (alfalfa) in Atlantic salmon feed.

Grass proteins to feed salmon?
To reduce its dependence on soy and find local, sustainable alternatives, the aquaculture sector is exploring new avenues.

The Norwegian University of Life Sciences (NMBU) and feed manufacturer Aller Aqua are testing the inclusion of alfalfa proteins in farmed salmon diets. Initial laboratory trials showed that fish growth was not affected, and that 5% alfalfa protein even improved certain welfare indicators. Grass proteins also influence fillet colour. These promising results pave the way for using alfalfa as a sustainable alternative to soy, and research will continue with sea-cage trials.

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Fish Welfare in Aquaculture

With the anticipated increase in fish production, the welfare of fish raised in intensive systems is raising growing ethical concerns and is expected to fuel public debate and policy discussions. Traditional methods for assessing fish welfare rely on physical, physiological, and behavioral indicators, providing information on health and biological functioning, but they have significant limitations.

Approaches based on affectivity, which use behavioral indicators to measure emotional state, are widely used in animal welfare science but remain little explored in fish. Recent advances, such as judgment bias paradigms, provide reliable tools for assessing these affective states.

By combining affective measures with health and biological functioning indicators, a multi-level approach enables a comprehensive and robust assessment of fish welfare, without being limited to a single type of evidence. The main contribution of this study is the proposal of a functional framework that prioritizes the assessment of affective state while systematically integrating and validating other measures. Aligned with current ethical and scientific standards, this approach contributes to improving the conceptualization and operationalization of fish welfare.