Influence of Dietary Replacement of Menhaden Oil with Canola Oil on Fatty Acid Composition of Sunshine Bass

Abstract

The replacement of menhaden Brevoortia spp. oil with graded levels of canola oil in diets fed for 20 weeks to sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) significantly impacted the fatty acid composition of fillets and livers. As the amount of canola oil increased from 0% to 100% of the oil in the diet, the amount of 18:1(n-9) and 18: 2(n-6) fatty acids in fillets increased linearly, whereas the amounts of 20:5(n-3), 22:6(n-3), long-chain n-3 highly unsaturated fatty acids (HUFAs), and total long-chain HUFAs in the fillets decreased linearly. Total long-chain n-3 HUFA levels did not differ significantly between fillets from fish fed a diet with 50% canola oil and those from fish fed 100% menhaden oil. The experimental diets also significantly altered the fatty acid compositions of the livers, though fatty acid levels were highly variable within and among treatments and differences usually were not as pronounced as differences in fillets. We observed no significant differences in weight gain, feed conversion, or total lipid content among fish fed the different diets. Our results suggest that high levels of canola oil in growing diets of sunshine bass could be used for the majority of the production cycle, to be followed by a “finishing” diet that would elevate HUFA levels, thereby increasing the fillets' nutritional benefit to the human consumer.

Notes

¹ In all fatty acid designations, the number to the left of the colon is the number of carbon atoms in the compound, the number immediately to the right of the colon is the number of double bonds, and the number after the hyphen indicates the position of the first double bond from the methyl end.