Introduction
Even though the rainbow trout sector represents 96% of the farmed fish production in France (roughly 39,000 tons in 2022 ; P��che et Aquaculture, 2022), it is criticized for its environmental impacts like the other sectors of animal production (Wilfart et al, 2023). Life Cycle Assessment (LCA) enables to evaluate some of the environmental impacts of aquaculture such as its impact on climate change and eutrophication. Moreover, LCA uses new indicators to study for example the impacts of aquaculture feeds on halieutic resources. In fact, fish feeds have been identified as the element of the life cycle mostly contributing to the impacts of aquaculture systems (25 to 95% of the studied impacts ; Wilfart et al, 2019). One of the ways to reduce these environmental impacts is by using eco-formulated feeds (Wilfart et al, 2023). If many studies have been conducted on the growing stages, a lot less have been dedicated to the production of fertilised rainbow trout eggs even though most of the fish farmers buy their fertilised eggs to specialised fish farms (P��che et Aquaculture, 2022). Thus, it is essential for this sector to develop and promote production methods that reduce its environmental impacts. The main goal of the PEPITO project, a FEAMPA project financed by the European Union, the French government and Brittany, is to use multi-objective formulation (MOF) to design eco-feeds for rainbow trout breeders. MOF uses simultaneously the nutritional needs of rainbow trout breeders, environmental durability criteria and economical data.
Material and Methods
For this project, the MOF algorithm used is adapted from the one developed by Garcia-Launay et al (2018) and modified by Wilfart et al (2023). The nutritional, incorporation and economical constraints were given by Le Gouessant Aquaculture and modified after several technical meetings to increase the range fo solution for the algorithm. The list of raw material was also given by Le Gouessant Aquaculture and supplemented with data collected from other feed manufacturers or with data from literature. The environmental constraints are calculated with the LCA impacts of the raw materials. Two eco-feeds issued from the algorithm were selected for the trial and their performances will be compared with two commercial feeds. The impacts studied are the ones of EF 3.1 supplemented with Net Primary Production Use (NPPU) and Phosphurus Comsumption (PC).
Results
The first results show a difficulty to obtain eco-feeds for rainbow trout breeders having a global environmental impact lower than the commercial feed, contrary to the results of the study conducted on the growing stage. The eco-feeds have a higher contribution on most of the studied impacts, except for NPPU, which is reduce by around 70%. Wheat gluten and soybean concentrate, which respectively represent around 5 and 15% of the feeds, are important contributors to the studied impacts, representing 10 to 40% of the studied impacts. Fish meal and fsih oil represents more than 97% of the impact on NPPU.
Discussion
This study shows that applying important nutritional constraints to formulate feeds for breeders lead to a difficulty to produce feeds with lower environmental impacts than the commercial feeds. This is due to the partial substitution of fish meal and fish oil, highly incorporated in breeders commercial feeds, with plant-based ingredients. In fact, plant-based ingredients have higher environmental impacts than fish meal and fish oil for most of the impacts studied, especially land use, ecotoxicology and climate change. However, plant-based ingredients are beneficial for the preservation of halieutic resources, observed through the NPPU indicator. The next steps of the project are the trials, which aim to check the zootechnical performances of the eco-feeds, and the conception of an eco-feed for rainbow trout larvae.
References
Garcia-Launay, F., Dusart, L., Espagnol, S., Laisse-Redoux, S., Gaudr��, D., M��da, B., & Wilfart, A. (2018). Multiobjective formulation is an effective method to reduce environmental impacts of livestock feeds. British Journal of Nutrition, 120 (11), 1298–1309. https://doi.org/DOI: 10.1017/S0007114518002672
P��che et Aquaculture. (2022). Consommation des produits de la p��che et de l'aquaculture 2021.
Wilfart, A., Dusart, L., M��da, B., Gac, A., Espagnol, S., Morin, L., Dronne, Y., & Garcia-Launay, F. (2019). R��duire les impacts environnementaux des aliments pour les animaux d'��levage. INRAE Productions Animales, 31(3SE-Articles), 289–306. https://doi.org/10.20870/productions-animales.2018.31.2.228
Wilfart, A., Garcia-Launay, F., Terrier, F., Soud��, E., Aguirre, P., & Skiba-Cassy, S. (2023). A step towards sustainable aquaculture: Multiobjective feed formulation reduces environmental impacts at feed and farm levels for rainbow trout. Aquaculture, 562, 738826. https://doi.org/https://doi.org/10.1016/j.aquaculture.2022.738826