Aquaculture Europe 2023

September 18 - 21, 2023


Add To Calendar 19/09/2023 17:00:0019/09/2023 17:15:00Europe/ViennaAquaculture Europe 2023EXPLORING THE INFLUENCE OF SARDINE COOKING WATER EXTRACTS ON THE SHORT-TERM REGULATION OF FEED INTAKE IN EUROPEAN SEABASSStrauss 2The European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982


 Daniela Resende abcde *,  Maria J. Pereira f , Tiago Sá a , Carla Brazinha f , Manuela Pintado c, Lui sa M.P. Valente ab , Cristina Velasco a


a CIIMAR/CIMAR-LA, Universidade do Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, S/N, 4450-208 Matosinhos, Portugal

b ICBAS, Universidade do Porto, Rua Jorge de Viterbo Ferreira, 228, 4050-313 Porto, Portugal

c CBQF – Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal

d GreenUPorto/INOV4Agro & DGAOT, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal

e Sense Test Lda., R. Zeferino Costa 341, 4400-345 Vila Nova de Gaia, Portugal

f LAQV/REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal

 *Presenting author. Email:



In fish, feed intake regulation is mediated by an interaction between homeostatic and hedonic signals

(Soengas et al., 2018)

 . The homeostatic control relates to biological  needs regarding nutrients and energy

. On the other hand, the hedonic control  is associated with reward-based routes, which are triggered by highly palatable food

. Hedonic control may override homeostatic a nd maintain a drive to eat, due to the sensory pleasure felt by eating. Increasing the palatability of diets, such as those with high l evels of plant-based ingredients, is therefore an important matter in aquaculture, as to achieve the best growth performance of fish.  In addition, to evaluate the potential of a diet to affect the hedonic regulation of feed intake, long-term growth trials may be inadequate, since  the need to maintain nutrient and energy homeostasis becomes more relevant over time . In parallel, the habituation effect to the diets occurs and  masks the impact of diet palatability.  Thus,  studying feed intake stimulants, preferably obtained from  by-products (considering a circular economy approach), on short-term trials may shed light on their impact on diet palatability and hedonic regulation of feed intake. In this work , we evaluated aromatic extracts from sardine cooking wastewaters as feed intake stimulants in plant-based diets for European seabass , focusing on the first feeding response towards the experimental diets.

Materials and methods

 Sardine cooking wastewaters were collected and either tested directly (CW-A) or after vacuum distillation (VD-A) or after liquid/liquid extraction with soybean oil (LLE-A), resulting in distinct chemical profiles. The most abundant compound in the three extracts was 1-penten-3-ol, being thus chosen as marker and included at 2 μg/g in isolipidic and isoproteic diets (CW, VD, LLE). A  practical plant-based  diet  (12.5% fishmeal and 4%  fish oil)  without any supplementation  was used as control. Each diet was assigned to six homogeneous groups of European seabass juveniles (96 g). Fish were sampled 2 and 6 hours after a single first meal distributed to apparent satiation . Metabolites including glucose, lactate, cholesterol and non-esterified fatty acids were quantified in the plasma. Additionally, the mRNA abundance of neuropeptides involved in the regulation of feed intake , namely  neuropeptide Y (npy) ,  agouti-related peptide (agrp2) ,  cocaine and amphetamine-related transcript (carpt2) and pro-opiomelanocortin (pomca ) was quantified in the hypothalamus and telencephalon.

Results and Conclusions

 Feed intake  after the first meal  was  significantly higher for the control diet than for the supplemented diets . No significant differences on plasma metabolites were observed. Although the expression of neuropeptides involved in feed intake regulation was statistically similar among diets and sampling points, LLE and VD diets displayed the lowest expression of the agrp2 in the telencephalon,  whilst  LLE diet led to the highest expression of pomca , 2 hours after feeding.

 The similar profile of plasma metabolites among diets suggests that the regulation of feed intake in the tested fish was driven more by hedonic factors, such as reward or pleasure-driven, rather than homeostatic  factors, such as nutrient-driven . The slightly lower expression of orexigenic (inducing feed intake) neuropeptide agrp2  in fish  and higher expression of anorexigenic (supressing feed intake) neuropeptide  pomca  may  be regulating factors associated with decreased  feed intake observed in fish fed LLE and CW diets, but other factors might have also contributed to such results . Overall, the sardine cooking wastewaters extracts, in the tested concentration, had no positive effect on the short-term feed intake response of European seabass , which suggests that feed palatability was not enhanced. Further optimization of the extracts’ production process, and/or inclusion levels in diets should be considered in both short and long-term trials to improve effectiveness of the extracts as feed attractants.


Díaz-Rúa, A., et al. (2022). The opioid system in rainbow trout telencephalon is probably involved in the hedonic regulation of food intake [Original Research]. Front Physiol, 13.

Soengas, J. L. (2021). Integration of nutrient sensing in fish hypothalamus. Front Neurosci, 15, 653928.

Soengas, J. L., et al. (2018). Central regulation of food intake in fish: an evolutionary perspective. J Mol Endocrinol, 60(4), R171-R199.


DR thanks FCT, SANFEED and Sense Test© for her PhD grant (PD / BDE/ 150524/ 2019). CIIMAR and GreenUPorto acknowledge funds provided by FCT - Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDB/05748/2020.