Replacement of fish oil with a DHA-rich algal meal derived from Schizochytrium sp. on the fatty acid and persistent organic pollutant levels in diets and flesh of Atlantic salmon (Salmo salar, L.) post-smolts

Abstract

The replacement of fish oil (FO) with a DHA-rich Schizochytrium sp. algal meal (AM) at two inclusion levels (11% and 5.5% of diet) was tested in Atlantic salmon post-smolts compared to fish fed a FO diet of northern (NFO) or southern hemisphere (SFO) origin. Fish were preconditioned prior to the 19-week experimental feeding period to reduce long-chain polyunsaturated fatty acid (LC-PUFA) and persistent organic pollutant levels (POPs). Dietary POP levels differed significantly between treatments in the order of NFO>SFO>11AM/5.5AM and were subsequently reflected in the flesh. Fish fed the 11AM diet contained similar DHA levels (g.100g -1 flesh) to FO-fed fish, despite percentage differences. However, the low levels of EPA in the diets and flesh of algal-fed fish compromised the overall nutritional value to the final consumer. Nevertheless, further developments in microalgae culture offer a promising alternative lipid source of LC-PUFA to FO in salmon feeds that warrants further investigation.