Abstract (EN):
Previous studies clearly suggested that conjugated linoleic acid (CLA) could be successfully incorporated up to 1% in rainbow trout diets contributing to the production of a functional food. The determination of the time course deposition of CLA has never been evaluated in fish. Hence, homogenous groups of 43 rainbow trout (Oncorhynchus mykiss) with an average initial body weight of 216.5 +/- 19.6 g were randomly distributed among 6 square fibre glass tanks (250 1), in an open flow-through system. Triplicate groups of fish were fed commercial extruded diets containing 0% CLA (control group) or 1% CLA, by hand to apparent satiety, for 12 weeks. Every 2 weeks, 18 trout from each treatment were sampled to evaluate whole body composition, muscle fatty acid profile and sensory properties. At the end of the experiment all groups of fish weighted more than 400 g and no significant differences were detected in growth performance, feed conversion, nutrient or energy utilization and body composition among treatments. In general terms, the muscle total saturated, monounsaturated and polyunsaturated fatty acids did not vary among dietary treatments, despite the increasing concentration levels of CLA. The muscle incorporation of the two biological active isomers increased gradually during the 12 weeks of feeding CLA reaching the maximum level (2.7% of total fatty acids) after 12 weeks. Nevertheless, after 8 weeks of feeding, the observed value (2.2% of total fatty acids) was not significantly different from the final. At every sampling point, sensory data indicated no significant differences between animals fed control and CLA diets. The present results suggest that feeding market size rainbow trout with 1% CLA, during an 8-week period, is enough to attain muscle CLA levels similar to those observed at 12 weeks. Moreover, a fast accumulation of CLA isomers in the muscle was registered, reaching 1.3% of total fatty acids just after 2 weeks of supplementation, which reinforces the potential of aquaculture fish to supply those bioactive fatty acids, becoming functional foods.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Contacto:
lvalente@icbas.up.pt
Nº de páginas:
9