Introduction
The world will be dependent on the development of novel feed ingredients from renewable sources to ensure sustainable growth of the aquaculture industry. A more balanced harvesting approach across the ecosystems can maintain ecological diversity in the oceans and make alternative marine resources available as future feed ingredients for aquaculture. Zooplankton like Calanus finmarchicus are viable raw material candidates, as they have optimal nutrient profiles for aquatic animals and may be sustainably harvested in large volumes. In this study, the aim was to investigate if a novel protein hydrolysate of C. finmarchicus could influence growth performance, oxidative stress, and intestinal health of European sea bass (Dicentrarchus labrax) juveniles in a feeding trial lasting 84 days.
Material and methods
The effect of dietary inclusion of hydrolysates was tested in a feeding trial with European sea bass juveniles, benchmarking calanus hydrolysate (CH) against other commercial hydrolysates of sardine, tuna, and salmon at 5 % inclusion. Fish were group weighed at day 0, 30, 67, and 84. Three fish per replicate tank were sampled for health assessments; the liver for analysis of oxidative stress (hepatic protein carbonyls and antioxidant enzymes), and faecal content for intestinal status (calprotectin and mucins). Data were subjected to a one-way analysis of variance (ANOVA), and means were compared with the Tukey method. Statistical significance was tested at a 0.05 probability level (n =3).
Results
CH improved growth performance of European sea bass juveniles, showing higher body weight and lower FCR compared to diets with other marine hydrolysates (Fig. 1).
The health assessment results at the end of the trial showed significantly lower oxidative stress (Fig.2A) and lower intestinal inflammation (Fig. 2B) in European sea bass juveniles fed diets with CH inclusion.
Conclusions
Dietary inclusion of CH at 5 % led to increased growth performance of European sea bass juveniles in the feeding trial. CH was also associated with significantly lower oxidative stress and less inflammation in the intestines, highlighting the potential of the hydrolysate as a functional feed ingredient for improved growth and health.
References
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S. Albrektsen, R. Kortet, P.V. Skov, et al. Future feed resources in sustainable salmonid production: A review. Rev Aquac. 2022; 14(4): 1790- 1812. doi:10.1111/raq.12673.
I. Bøgwald, A. Pedersen, T-K, Østbye, S. Rønning, J. Dias, K-E. Eilertsen, S. Wubshet. (2023). Calanus finmarchicus hydrolysate improves growth performance in feeding trial with European sea bass juveniles and increases skeletal muscle growth in cell studies. Manuscript submitted to Scientific Reports.
I. Bøgwald, A. Pedersen, J. Dias, S. Wubshet, K-E. Eilertsen. (2023). Dietary protein hydrolysate from Calanus finmarchicus reduces oxidative stress and increases intestinal health in European sea bass juveniles. Manuscript in development.