Marine fish larvae present very high growth rates, hence, are quite susceptible to stress. Thereby, a tailored nutrition is essential to fulfil larvae growth potential and promote resilience. Several plant-derived extracts are considered promising feed additives, since is possible to maximise protein accretion, improve metabolic plasticity, and reduce stress while increasing fish resilience. The aim of this study is to provide a nutritional approach, to respond to some of the current challenges of marine hatcheries. Therefore, the potential of these natural additives as promoters of oxidative status, and muscle protein accretion are explored, at early stages of development of Senegalese sole (Solea senegalensis) and turbot (Scophthalmus maximus).
A 4-week growth trial with Senegalese sole postlarvae (45 days after hatching, DAH) fed with one of four experimental diets - control (CTRL), and supplemented with curcumin (CC), green tea (GT), and grape seed (GS) extracts. A second 5-week growth trial with turbot postlarvae (23DAH) fed with one of three experimental diets - control (CTRL) and supplemented with curcumin low dose (CCL) and curcumin high dose (CCH). After 3 weeks of feeding with the experimental diets, turbot (65DAH) were fed a commercial diet until the end of the experimental period. A thermal stress test was conducted at the end of both trials to assess how the dietary treatments modify the fish physiological responses.
Sole growth was improved by CC and GS diets when compared to those fed the CTRL. CC and CTRL postlarvae presented the lowest oxidative damage. Stress-related biomarkers decreased in CC fish compared to those fed the CTRL diet. Turbot growth was negatively affected by the higher inclusion dose (CCH) at 50DAH. After the feeding period with the commercial diet, all turbot presented similar weight independently of the dietary treatment. However, turbot fed CCL that presented similar weight to CTRL fish, presented a better total antioxidant capacity when compared to no-supplemented fish.
In conclusion, while dietary curcumin supplementation was able to promote growth and robustness through a modulation of the oxidative status in Senegalese sole, only the latter was observed in turbot (Fig. 1).
Acknowledgements: This work is part of MAXIMUS.PT project (ref. 69769) supported by Portugal and the European Union through FEDER, COMPETE 2020 and CRESC Algarve 2020, in the framework of Portugal 2020; and co-financed by the Portuguese Foundation for Science and Technology through projects UIDB/04326/2020, UIDP/04326/2020, LA/P/0101/2020 to CCMAR.