Effect of phytate and phytase on the protein degradation systems and growth performance of meagre, Argyrosomus regius (Asso, 1801) juveniles

• Autor(a) principal: Calvinho, Laura Vaz
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/18428
• topic: Phytate; Phytase; Protein degradation systems; Growth performance; Meagre (Argyrosomus regius)

The production of meagre (Argyrosomus regius) is of great interest in the Mediterranean region and southern Europe due to its easy adaptation to captivity, rapid growth (± 1 kg / year), high larval survival rates and tolerance to environmental stress, in terms of temperature and salinity. The aquaculture industry is facing a huge challenge, which is to find economically and ecologically viable alternatives to fishmeal and oil. There are some plant-derived ingredients, such as soy protein or wheat gluten, which are good candidates for replacing fishmeal, however most plant-derived ingredients have nutrient imbalances, lower nutrient digestibility and anti-nutritional factors. The present study aims to evaluate the effect of phytate, an anti-nutrient found in ingredients of vegetable origin, and phytase, an enzyme that degrades phytate, on the growth performance and protein degradation systems of meagre juveniles. A trial was carried out with 900 juvenile meagres randomly distributed through 9 tanks, in order to have triplicates for each diet. Fish were fed three experimental diets (CTRL, D1, D2) containing a high percentage of plant ingredients for 30 days. Extra amount of phytic acid (= phytate) was added to diets D1 and D2. The manufactured diets CTRL, D1 and D2 contained 0.14% dry matter (DM), 0.19% DM and 0.13% DM of phytate, respectively. Beyond phytate, diet D2 contained also 1000 FTU kg-1 feed of the phytase enzyme. The addition of phytic acid to diets D1 and D2 had no significant effects on growth performance and feed utilization of juvenile meagre. The results obtained from the activity of cathepsins, the activity of the proteasome and the expression of the Psmb4 subunit of the proteasome were also not significant in the two tissues analyzed (muscle and liver). Thus, this study indicates that the amount of phytate added to the diets was not enough to affect growth performance of meagre juveniles, so the addition of phytase in the D2 diet may not had any functionality.