PREPARING A FEED FROM AGRI-FOOD INDUSTRIES BY-PRODUCTS FOR Hediste diversicolor
Introduction
Hediste diversicolor is characterized by its ability to elongate and desaturate long-chain polyunsaturated fatty acids from substrates of low nutritional quality (Villena et al., 2025). This, alongside its high protein content, makes it a potential alternative ingredient for the aquafeed industry in a context of sustainability and circular economy. The production of H. diversicolor biomass for use as feed in aquaculture—whether in its raw form or as meal—requires optimizing its cultivation, which makes it essential to have access to a suitable feed at the lowest possible cost. This study evaluates diets formulated from agri-food industry by-products in terms of growth performance and the resulting fatty acid profile.
Materials and methods
After a preliminary selection process of raw materials derived from waste products from the wine, beer, cider, and aquaculture industries (Aguado-Giménez et al., 2025), along with the inclusion of other raw materials typical of the aquaculture feed industry (to ensure an adequate protein intake), we formulated four diets for H. diversicolor. Table 1 shows the proportions of each raw material used in each of the four diets and their basic nutritional composition.
Table 1: Ingredient and nutritional composition (%) of the four formulated feeds. RoWL: rose wine lees; BSG: brewer´s spent grain; BFL: biofloc waste.
RoWL
BSG
BFL
Soy meal
Meat meal
Protein
Lipids
SUB_1
70
20
10
-
-
31.89
4.33
SUB_2
70
30
-
-
-
33.22
4.83
SUB_VEG
50
20
10
20
-
34.21
5.52
SUB_AN
50
20
10
-
30
34.11
5.70
A growth trial was performed usind ad hoc experimental units (EU) and following the experimental apparatus described in Aguado-Giménez et al. (2023), at a density of 2,000 individuals m-2, a temperature of 18 °C, and a salinity of 35‰, for 2 months.. Specific growth rate (SGR), Survival Rate (SR) and the resulting fatty acid (FA) profile were assessed.
Results and Discussion
SR was very close to 100% with all diets. SGR was significantly lower with the SUB_2 diet. The other diets resulted in very similar SGR values, which were slightly higher with SUB_1 and SUB_AN (Figure 1). H. diversicolor significantly transformed the dietary fatty acid profile into biomass richer in PUFAs and omega-3 fatty acids (Figures 2-4). Polychaetes fed the SUB_1 and SUB_2 diets had a fatty acid profile distinct from that obtained with the other diets (Figure 2), characterized by a higher content of LC-PUFAs, particularly those of the ω-3 series. In general, worms fed any of these diets showed a significant increase in the proportion of PUFAs, particularly EPA and ω-3 series as a whole, compared to their respective diets (Figures 3-4).
Figures 1-4: 1: SGR obtained with the four formulated diets; 2: and discriminant analysis for the fatty acid profile of the worms fed with the four diets; 3: Fatty acid profile of the four diets; 4: Resulting fatty acid profile of worms fed the four diets.
Of the four formulated diets, diet SUB_1 was selected to enhance H. diversicolor biomass production for subsequent experiments involving its inclusion in marine fish feed. This diet provided the best balance between growth performance, fatty acid profile, and compliance with circular economy criteria.
Acknowledgment
This study is part of the POLYPUFA project (PID2022-136234OB-C22) funded by the Spanish Ministry of Science and Innovation and Universities (MCIN/ AEI/10.13039/501100011033). Authors also wish to thank to the following collaborating Spanish agri-food industries: Rocker Beer Brewery (Cantabria), Bodegas Ramón Bilbao (La Rioja), and Escalante Pomological Association (Cantabria).
References
Aguado-Giménez et al (2023). https://doi.org/10.3390/aquacj3010004
Aguado-Giménez et al (2025). https://eposters.blob.core.windows.net/eas-eposters/AE2025AbstractBook.pdf
Villena et al (2025). https://doi.org/10.1007/s10499-024-01679-x