Introduction
Currently, aquaculture faces two major challenges: the reduction of fish meal inclusion in feeds and the diversification of farmed species. Mugilids (family Mugilidae ) emerge as a promising group to address these challenges, their omnivorous feeding habits allow a lower protein content in diets formulation . However, as has been observed in other species, the protein quality is critical to ensure proper growth , for this is essential to cover amino acid requirements. The objective of this study is to analyze the amino acid profiles of various sustainable feed ingredients and assess their suitability for three different mugilid species.
Materials and methods
The whole-body composition and amino acid profiles were analyzed for three fishes from three different wild mugilid species (Mugil cephalus , Chelon labrosus , and Liza aurata ) at the laboratorie of the Universitat Politècnica de València (UPV). In parallel, the crude protein content and amino acid composition of different raw materials—vegetal, aquatic animal, terrestrial animal, and unicellular origin—were analyzed. Based on the amino acid data, the following nutritional indices were calculated: Amino Acid Ratio (AAR % = (AAsample)/(AAreference)*100), Chemical score (CS, %: Minimum value from AARs ), Limiting amino acid (The a mino acid that correspond to CS) and Oser ´s Index (OI, % = 10(1/n*(log(AAR1)+log(AAR2)…log(AARn)))
Results
The results obtained show that the most limiting amino acid in different raw materials was methionine (MET) followed by lysine (LYS) (Table 1) , depending on the species. For Mugil cephalus , methionine was the most limiting amino acid while for Chelon labrosus were methionine and lysine and, finally , lysine was the limiting amino acid for Liza aurata.
In general, Chelon labrosus showed better IO and CS than the other two species for all raw materials. The IO index was higher in raw materials of aquatic animal origin (Figure 1) followed by Brewer’s yeast 100%, Fermented soybeans, Potato protein and Beet pulp. For CS was similar than IO index and fish meal had the best CS. However, Brewer’s yeast 100% showed better CS than krill and other raw materials had close to these values . and terrestrial raw materials and some vegetables raw materials had the worst values to OI index and CS.
Discussion
Results obtained indicate that, depending on the species, different dietary formulations are required to meet specific amino acid requirements. Normally, raw materials, which are not of marine origin, are deficient in methionine and lysine and those of vegetable origin have less protein. The protein and amino acid requirements vary according to the developmental stage of the fish and the specie . Therefore, it is necessary to utilize different combinations of raw materials even within the same species due to the substitution of fish meal with a single alternative protein source should not exceed 40% (Sánchez-Lozano et al., 2009; Valverde et al., 2013). One of the advantages of feed formulation in aquaculture is the ability to combine multiple raw ingredients to compensate for limiting amino acids and to ensure optimal growth performance.
Acknowledgments
This work was supported by Generalitat Valenciana (GVA AICO/2021/198). J. Brol has a predoctoral grant from Generalitat Valenciana (Programa Santiago Grisolía 2021; CIGRIS/2021/109) and R. Olivares-Perona a technician contract from ThinkInAzul programme funded by the Spanish Ministry of Science and Innovation with European Union NextGenerationEU funds (GVA-THINKINAZUL/2021/006)
References
Sánchez-Lozano, N. B., Martínez-Llorens, S., Tomás-Vidal, A., & Jover Cerdá, M. (2009). Effect of high-level fish meal replacement by pea and rice concentrate protein on growth, nutri ent utilization and fillet quality in gilthead seabream (Sparus aurata L.). Aquaculture, 298(1-2), 83–89.
Valverde, J. C., Martínez-Llorens, S., Vidal, A. T., Jover, M., Rodríguez, C., Estefanell , J., Gairín , J. I., Domingues , P. M., Rodríguez, C. J., & García, B. G. (2013). Amino acids composition and protein quality evaluation of marine species and meals for feed formulations in cephalopods. Aquaculture International, 21(2), 413–433. https://doi.org/10.1007/s10499-012-9569-6