Is royal jelly a sustainable alternative lipid source in aquaculture? Influence of dietary royal jelly levels on fatty acid composition in zebrafish

. ABSTRACT. Royal jelly (RJ) is a bee-derived product widely used as a dietary supplement due to its high potential health benefits. The present study was designed to investigate the effect of feeding RJ on zebrafish fatty acid composition. Zebrafish were fed five distinct diets (D1, D2, D3, D4, and D5) for 56 days supplemented with 0.0, 0.1, 0.4, 1.6, and 6.4% RJ, respectively. Gas chromatography-mass spectrometry and fatty acid methyl ester (FAME) analyses were used to determine FA content in the whole body of zebrafish. The results showed that a feeding regimen that included incrementing RJ doses resulted in statistically significant increases in 16:0, 18:2n-6, and the ratio of eicosapentaenoic acid (EPA) to docosahexaenoic acid (DHA) ( P < 0.05). In particular, the content of EPA/DHA increased up to 1.3-fold compared to control group D1. Conversely, increasing RJ levels led to significant decreases in DHA, HUFA, and n-3/n-6 PUFA levels in relation to group D1 ( P < 0.05). In conclusion, considering the EPA/DHA ratio among the analysed fatty acids, the diet with a 1.6% RJ addition was the optimal choice. Therefore, RJ can be recommended as a sustainable alternative lipid source in aquaculture.