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Browsing by Author "Viegas, Ana Teresa Gomes"

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  • Growth performance and liver alterations of meagre (Argyrosomus regius, Asso, 1801) fed plant-based diets supplemented with fish or krill oils
    Publication . Viegas, Ana Teresa Gomes; Engrola, Sofia; Pousão-Ferreira, Pedro
    Meagre (Argyrosomus regius) is a species of marine carnivorous fish that have a high demand for protein and lipids, with fish meal (FM) and fish oil (FO) as the main ingredients included in its diet. Currently, replacement of FM by plant proteins can be achieved in diets containing FO as the main lipid source, without affecting growth performance. However, FO has been over-exploited, and krill oil (KO) appeared as an alternative source, since KO is known to be a rich source of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) (namely, eicosapentaenoic acid - EPA and docosahexaenoic acid - DHA), which is crucial for the normal growth of marine fish. The alteration of the dietary fatty acids (FA) profile, for instance, through the replacement of FO by KO in plant-based diets may modify the contents of n-3 LC-PUFA, affecting fish growth. Thus, a 71-days feeding trial was conducted to evaluate the effect of FO replacement by KO in plant-based diets for meagre juveniles. Two experimental diets were formulated with different lipid sources – FO (1.18 and 0.60% of EPA and DHA, respectively) and KO (0.36 and 0.19% of EPA and DHA, respectively). Six homogeneous groups of 60 fish (13.20 ± 0.10 g and 5.28 kg/m3 of initial weight and density, respectively) were randomly distributed into each tank and the experimental diets were randomly assigned in triplicate. The results showed that, in general, survival and whole-body composition of fish were not significantly (p<0.05) affected by the replacement of FO by KO. Nevertheless, reduced levels of EPA and DHA in KO diet affected negatively (p<0.05) growth performance, feed utilization, muscle and liver FA profile, and liver structure of fish. In conclusion, although KO could be a good energy source improving the cost effectiveness of the diet, present results suggested that FO cannot be totally replaced by KO without affecting the normal growth of meagre juveniles. Further research is needed to investigate the feasibility of supplementation of EPA and DHA in plant-based diets for this species.
    2021-12-15Master thesis Open access Show more