Effects of algal oil as an alternative to fish oil in feline foods on serum concentrations of eicosapentaenoic acid and docosahexaenoic acid.

Fish oil is a source of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that confer several health benefits. To ensure continuity in the supply of n-3 fatty acids, alternative sources are being sought. Algal oil may serve as a promising alternative to fish oil for supplementing DHA in cat foods. The purpose of this study was to determine if the inclusion of algal oil in place of fish oil in feline foods would result in similar serum EPA and DHA concentrations. Cats were first fed a control food for 5 wk and then randomized into two groups and fed test foods containing either fish oil or algal oil in sequential increasing concentrations of DHA (0.2, 0.4, and 0.6%). Serum was analyzed at the beginning and end of each of these 5-wk feeding periods. Oil type had no effect on the body weight of cats consuming foods containing either algal oil or fish oil; only cats that consumed the algal oil food with 0.6% DHA had a significant decrease from baseline in food intake (P = 0.0011). Analysis of serum fatty acid concentrations showed that serum DHA increased at similar rates when fish oil and algal oil levels were increased in the food. Although increasing levels of fish and algal oil both increased serum EPA concentrations, the higher concentrations of EPA in the fish oil foods resulted in higher circulating concentrations of EPA in those cats. Algal oil was included at levels 3.7-fold lower than fish oil due to the high DHA content of algal oil. Overall, these data indicate that algal oil may serve as a good alternative dietary source of DHA. Fatty acid profiles of algal oil should be considered when selecting a replacement for fish oil in feline foods.