ASSESSING THE VALUE OF SINGLE CELL PROTEINS IN SALMONID PRODUCTION
This study evaluated the use of a novel single cell protein (SCP, Protopia) as a sustainable alternative to fish meal and soy protein concentrate in rainbow trout (Oncorhynchus mykiss) diets. The feeding trial was conducted at CRNA (Village-Neuf, France) over 11 weeks, using juvenile trout with an initial body weight of 90.65±0.46 g. Five dietary treatments were formulated: a commercial-like control and four diets with increasing SCP inclusion levels (2.5%, 5%, 10%, and 15%), each in triplicate. Feed formulations were balanced for crude protein (~38.5%) and lipid (~24.4%), with amino acid supplementation to ensure nutritional adequacy. Growth performance, digestibility and immune response were assessed after 77 days of experimental feeding.
Results and conclusions
Results indicate that all SCP inclusion levels support comparable body weight gain and final body weight to the control diet. Specifically, final body weight ranged from 342.2g to 350.0g, across treatments. Results show that the tested SCP can replace conventional protein sources in salmonid diets while maintaining growth performance and improving protein (Figure 1) and selected amino acid digestibility (Figure 2) at higher inclusion levels, without compromising immune function or nutrient retention.
In summary, the trial demonstrates that SCP can replace fish meal and soy protein concentrate up to 15% without compromising growth or health under experimental conditions.
These findings support SCP as a promising, sustainable protein source for aquafeeds, contributing to responsible consumption, and life below water (SDGs 2, 12, 14). These results indicate that value creation from SCPs lies not only in sustainable protein supply, but in predictable nutrient utilization, supporting precision feed formulation. Targeted inclusion levels (10–15%) should be prioritized in future development to maximize digestibility benefits while safeguarding gastrointestinal functionality.
Figures
Figure 1: Protein apparent digestibility coefficient (%). Data are presented as mean ± SD (Standard Deviation). Significant differences (p<0.05) are shown by different letters. N=3.
Figure 2: Apparent digestibility for individual amino acids. Significant differences (p<0.05) are shown by an asterisk. N=3.