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Microencapsulation of taurine in Senegalese sole diets improves its metabolic availability

2014; Elsevier BV; Volume: 431; Linguagem: Inglês

10.1016/j.aquaculture.2014.04.041

1873-5622

Cláudia Aragão, Rita Colen, Sara Ferreira, Wilson Pinto, Luís E.C. Conceição, Jorge Dias,

Aldose Reductase and Taurine

Abstract Senegalese sole farming is gaining “momentum” and the development of an optimised diet is pivotal to ensure its competitive and sustainable commercial culture. The lower fish performance often observed when replacing large amounts of dietary fishmeal by plant protein sources may result from an unbalanced supply of selected nutrients, such as taurine, which is absent in plants but abundant in fish. However, taurine is highly soluble in water and sole has a passive feeding behaviour. Therefore, the aim of this study was to test different forms of taurine inclusion in plant protein-based diets, in order to guarantee a reduced leaching of this nutrient to the environment and to ensure a reliable delivery at fish tissues. Two basal diets were formulated: a fishmeal-rich (FM) and a low fishmeal (PP85) diet, in which vegetable protein sources replaced 85% of marine-derived proteins. Based on the PP85 formulation, diets were supplemented with: crystalline l -taurine (FreeTau), encapsulated taurine microparticles (EncTau), or delayed-release taurine microcapsules (DRTau). Leaching experiments were performed for each diet and post-prandial taurine kinetics was analysed in plasma samples of Senegalese sole tube-fed with the experimental diets. Results showed that taurine losses in the FreeTau diet increased exponentially after 5 min of water immersion, reaching 100% after 15 min. Taurine encapsulation significantly reduced taurine losses after 15 min to 25% (EncTau diet) or 40% (DRTau diet). Taurine was rapidly absorbed in FM and FreeTau diets, attaining a peak in plasma at approximately 1 h after feeding. Taurine kinetics was quite different in fish fed with the encapsulated diets, as plasma levels were maintained elevated during an extended period of time. Maximal levels in diet EncTau and DRTau were attained at 1 and 6 h after feeding, respectively, demonstrating the successful production of sustained and delayed-release microcapsules. Taking into account its passive feeding behaviour, this study indicates that taurine should be previously encapsulated in diets for Senegalese sole. Depending on the objective of the study and on the feeding strategy adopted, encapsulated or delayed-release taurine microparticles should be used.