Effect of Dietary Vitamin C and E in Larval Performance and Incidence of Bone Anomalies in Meagre (Argyrosomus regius)

The meagre (Argyrosomus regius) is a candidate species for the diversification of aquaculture, which is a target species in the EU funded project Diversify. Studies on the recommended dietary levels of different nutrients are among the tasks of this project. Marine fish larvae are quite vulnerable to biotic and abiotic conditions, being submitted to a high oxidative risk. Vitamin E is an important antioxidant component of animal tissues, being essential for the protection of polyunsaturated fatty acids (PUFAs) against oxidative damage in biological membranes. Besides, in the development of teleost fish, ascorbic acid (AA) have also an important antioxidant role and interferes as a cofactor in biological processes, particularly related to immune, neural and skeletal systems. Specifically, this vitamin plays an important role in collagen synthesis, connective tissue, and formation of bone matrices (Wilson and Poe, 1973). Being marine fish larvae so susceptible to oxidation, the main aim of this study was to determine the role of both vitamins in biological performance, skeletal development and antioxidant enzymes complexes in larval meagre. For this purpose, three diets were tested, the lowest level of vitamin E and C 215/65 mg kg-1 respectively (LEC), the medium level 705/1170 mg kg-1 (MEC) and the highest 1396/1786 mg kg-1 (HEC) in meagre larvae at 18 DAH, and during 17 days of feeding. The effect of the combination of both vitamins was analyzed in survival and growth. The larvae fed on HEC diet obtained the greatest survival and MEC larvae presented the highest total length. Regarding histological analysis, a fair absorption, accumulation and transport of lipid, in the larvae fed on MEC diet. In ostological evaluation cephalic deformities appear to decrease when the amount of vitamin C increase in the diet. The percentages of severe deformities in the vertebral column showed that Extreme doses of vitamin C are less influential in skeletal elements. Finally, the development of the specific primers for meagre allowed to measure gene expression in MGP, OC, CAT, HSP70 and 90. In the MGP and OC expressions was found reduced development with low vitamin content in the diet. Besides, the CAT results support that these genes are regulated by oxidative stress but the amount of vitamin has no effect and depends on fissh species and organ analyzed. In HSP 70 and 90 case, they had a very low expression, which show the non-constitutive activity and their expression increase only after a severe stress situation.