Aquaculture´s sustainability relies on the identification and implementation of alternative raw materials to replace fish meal and oil. European countries (among others) also depends on the production of soybean meal (SBM) from third countries. H ere we will review the research works conducted to explore the potential use of Narbonne vetch (Vicia
narbonensis ) meal (NVM) as a substitute of SBM in rainbow trout (Oncorhynchus mykiss) diets.
The evaluation of NVM in rainbow trout diets
was developed in 3 research phases. In phase 1, the effects of the inclusion of NVM at 0%, 10% and 30% (C, A10 and A30, respectively) in diets (isoproteic
43%, isolipidic 18%) was explored . In phase 2, the substitution of SBM with 0% 33 % and 66 % of NVM was evaluated under pre-treated conditions with the exogenous enzyme rovabio® phytase or not in diets (C, A33, A33E, A66, and A66 E, respectively; isoprotein 42%, isolipidic 18%). Both experiments were carried out in RAS
units with 500 L tanks,
with a daily feed intake of 3% and during a 63-days trial . In phase 3, the underlying mechanisms of the effects of SBM substitution by NVM were explored through the assessment of digestive enzyme activities (proteases, α-amylase, alkaline phosphatase), blood biochemistry (glucose, triglycerides, cholesterol, among others) and
the quantification of the expression of genes involved in glucose metabolism.
We first reported that NVM can be safely included at 10% in rainbow trout diets (Fig. 1A); since 30% inclusion induced growth reduction and impaired status on the proximal intestine (Fig. 1B). Afterwards, we demonstrated that a 33% of SBM can be replaced by NVM when is pre-treated with the exogenous enzyme
(Fig. 1C).
Altogether suggest that a 33 % substitution of SBM by NVM can be used for rainbow trout diets when it was pre-treated with an exogenous enzyme.
Acknowledgments: This work was partially funded by “Optimización integral de los sistemas productivos en acuicultura: revalorización de materias primas locales en piensos y en cría de especies en potencial desarrollo (OPTI-ACUA)” project from the European Regional Development Funds (ERDF). F.J. T-S. acknowledges the National Council for Science and Technology (CONACYT) for the post-doctoral fellowship No. 2019–000012-01EXTV-00292. I.F. acknowledges the Ramón y Cajal (Ref. RYC2018-025337-I) contract from MICIU and the European Social Fund, “The European Social Fund invests in your future”. Authors also thanks the support from the network LARVAplus (117RT0521) funded by the CYTED.