Larval rearing protocols for European seabass (Dicentrarchus labrax) are well established, and current research aims to optimize these practices, particularly during early life stages and under routine stress conditions. Early nutritional programming plays a critical role in shaping robustness, growth, and overall performance throughout the production cycle (Hou and Lee, 2020).
This study aimed to evaluate how different early feeding strategies – specifically, the use of novel dietary formulations produced by hot extrusion technology and the enrichment of feed with natural functional extracts – affect the performance and stress response of European seabass in early development stages.
Two independent feeding trials were conducted. In Trial 1, seabass larvae (62–86 days after hatching, DAH) were fed four diets: (A) control commercial diet, (B) adaptation of a commercial diet with a different extrusion technology, (C) adaptation of a commercial diet to a different extrusion technology and replacement of crustacean meal, and (D) adaptation of a commercial diet to a different extrusion technology and replacement of protein hydrolysates. At the end of the trial, fish underwent an air exposure stress test. In Trial 2, post-larvae (98 DAH) were fed for one week with diets supplemented with Ulva spp., Tetraselmis spp., Euglena spp., or grapeseed extracts, followed by air exposure and Photobacterium damselae subsp. piscicida challenge.
In Trial 1, no negative effects of the extrusion method or ingredient replacement were observed on growth, survival, or stress resistance, paving the way for the use of different technologies for microdiets manufacture and ingredient replacement. In Trial 2, functional diets had limited baseline effects on stress-related gene expression, but algae extract inclusion significantly reduced stress markers (e.g., hsp90) and modulated antioxidant players (such as cat, sod, gpx gene expression and enzymatic activity) after stress exposure, indicating a protective effect in stressful situations.
These findings reinforce the relevance of tailored early feeding strategies, from novel extrusion technology to functional supplementation in microdiets, as promising tools to promote fish robustness and performance. Optimization of diet formulation and timing is essential to achieve consistent and sustainable results in marine larviculture.
This work was supported by PACTO DE INOVAÇÃO BIOECONOMIA AZUL (Project No. C644915664-00000026), SAUDE&AQUA II (MAR-021.1.3-FEAMPA-00018), and INOVAQUA (MAR-021.1.3-FEAMPA-00004). The technical assistance of EPPO and S2AQUAcoLAB staff was highly appreciated throughout the study.
Hou, Z., Fuiman, L.A. Nutritional programming in fishes: insights from mammalian studies. Rev Fish Biol Fisheries 30, 67–92 (2020). https://doi.org/10.1007/s11160-019-09590-y