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Browsing by Author "Ribeiro, Catarina Baptista"

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  • Improvement of gracilaria sp.efficiency as ingredient in European seabass diets
    Publication . Ribeiro, Catarina Baptista; Varela, J.; Batista, Sónia
    The aim of this study was to evaluate the effect of Gracilaria gracilis inclusion in European seabass (Dicentrarchus labrax) diets and to analyse if the application of technological processes and additives in these diets can enhance their benefits to fish. The fish parameters evaluated were growth performance, feed efficiency, body composition, apparent digestibility of nutrients, innate immune response, and intestinal morphology. Six experimental diets were formulated to be isoproteic (53.4% Dry matter), isolipidic (14.6% Dry matter) and isoenergetic (22.3 kJg-1 Dry matter). A commercial-based diet was used as control diet (CTRL) and compared to other five diets with 8% inclusion of G. gracilis, namely: entire G. gracilis (GRA), after physically process (PHY), supplemented with 0.02% of phytogenic compounds (PFA), 2.5% of oligo-alginates (OLIGO), or 0.08% of nucleotides (NUCL). Dietary treatments had no effect on growth performance, voluntary feed intake, feed conversion ratio, protein efficiency, and final whole body composition. There was a decrease of muscle dry matter with the inclusion of phytogenic compounds and oligo-alginates comparing with the CTRL group. Dietary treatments with entire G. gracilis, phytogenic compounds and oligo-alginates had decreased the hepatosomatic index comparing to the CTRL group. The physical process of G. gracilis improved the apparent digestibility coefficient and nutrient balance of diets with G. gracilis inclusion. Furthermore, the oligo-alginates and nucleotides increased the protein digestibility of these algae. The physical process and oligo-alginate increased the nitrogen gain and decreased the nitrogen faecal losses. In relation to phosphorus digestibility, there was only a significantly decrease in fish fed with NUCL, which was not reflected in phosphorus faecal losses. The innate immune system was not affected by the dietary seaweed treatments. There was a decrease of villus width in anterior intestine with GRA diet, which was improved by physical process (Patent WO/2019/171293), oligo-alginates and nucleotides. There was a positive correlation between villus width and the protein and energy digestibility. Our findings suggest that physical process can improve the digestibility and nutrient absorption of diets with 8% G. gracilis without compromise growth performance, immune response and intestinal health. In addition, oligo-alginates and nucleotides could also improve G. gracilis application with advantages on protein digestibility and intestinal health.
    2019-12-17Master thesis Open access Show more