The effects of phase-feeding rainbow trout (Oncorhynchus mykiss) with canola oil and Alaskan pollock fish oil on fillet fatty acid composition and sensory attributes

Abstract

Rainbow trout (186 g) were fed three test diets where the lipid source (150 g kg−1) was either menhaden oil (MO), pollock oil (PO) or canola oil (CO) for eight weeks to an average weight of 370 g. The CO group was then divided into two groups, one continuing on the CO diet and the other switched to the PO diet (CO–PO). After nine additional weeks of feeding, the average fish weight approximately doubled (719–749 g). No significant differences were found in average final weight or fillet yield among dietary treatment groups. Fatty acid profiles of fillets from trout fed MO, PO or CO-supplemented diets reflected the fatty acid profiles of the added oils, whereas the fatty acid profile of fillet from trout in the CO–PO group exhibited values similar to those of fish fed PO. The ratio of ω3 : ω6 FA was nearly 2.5 times higher in fillets from the CO–PO group compared to the CO group. Sensory analysis showed that panelists preferred CO-fed fillets over those fed MO, PO, or CO–PO. Phase-feeding CO and PO reduced fish oil use and resulted in fillets with double the content of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) over CO-fed fish, similar to levels in MO-fed fish.