Background/Aims: Aquaculture is encountering sub-optimal conditions due to changing environments. Simultaneously, shortages in marine oils are resulting in a reduction of dietary LC-PUFA . The effects of water temperature and dietary ARA/EPA ratios on the regulation of FA metabolism in salmon were investigated.
Methods: Atlantic salmon kept at optimal (10 °C) and elevated (20 °C) temperature were fed one of three experimental diets. The diets had identical FA composition with the exception of the EPA/ARA ratio, varying from 2.4 to 0.1. The FA metabolism was assessed via the whole-body-fatty-acid-method and selected genes expression was quantified by qPCR.
Results: The higher temperature showed an increase in the total FA β-oxidation (from 1,645.3 to 814.5 nmol/g/day at 20°C or 10 °C, respectively). At both temperatures, the β-oxidation of SFA and MUFA was lower in group with highest dietary EPA supply. The higher temperature showed a reduction in the activity and gene transcription of FA desaturases (D6fad and D5fad)and elongase Elovl2, whereas elongase Elovl5 was not affected. The metabolic fate of ARA was affected by temperature and dietary treatment. Whereas, in fish held at 20 °C, the metabolic fate of dietary EPA was identical for all three treatments.
Conclusions: Temperature plays remarkable effects on EPA and ARA metabolism. Increased dietary ARA supply, relative to EPA, is beneficial in fish held at elevated water temperatures. These findings contribute towards the formulation of novel functional aquaculture diets.
Funding source: This research was supported under the Australian Research Council's Discovery Projects funding scheme (Project DP1093570).