Effect of the low level dietary inclusion of queen bee larvae meal on the fatty acid profile of the fillets and livers of European seabass

Amidst growing interest in using insects for animal feed, studies are investigating new species like Apis mellifera queen bee larvae (QBL). QBL, a byproduct of royal jelly production, offers promise for circular economy practices and possesses functional potential, due to royal jelly enrichment on their body left by the harvesting. This study aimed to assess the impact of dietary inclusion of queen bee larvae meal (QBLM) at 1%, 2%, or 3% (QBLM1, QBLM2, and QBLM3) on the fatty acid composition of Dicentrarchus labrax livers and fillets. Over 180 days, 120 fish (30 fish/treatment) were reared in 12 tanks. After euthanasia using clove oil, total lipids, fatty acid (FA) profiles, atherogenic index (IA), thrombogenic index (IT), and elongase and desaturase Δ5 + Δ6 (n-3) and (n-6) activities were determined, using one-way ANOVA for statistical analysis.Linoleic acid was significantly higher in the CTRL (no QBL inclusion) livers (p = 0.0079), whilst the linolenic acid was more abundant in QBLM3 group (4.17% total FAME) compared to the CTRL (3.78%) and the QBLM1 and QBLM2 (3.71 and 4.04%). Additionally, C20:3n-6 content was notably more present in the CTRL group (p = 0.0032). No differences were detected for IA, IT, or enzymatic activity in livers. In fillets, C16:0 peaked in QBLM1 (p = 0.0168), C20:0 was greater in CTRL than in the treatments, and C22:1n-9 was significantly higher in the QBLM3 (0.31% total FAME) than other groups. Contrarily to the liver, elongase activity was significantly lower in the QBLM1 fillets (p = 0.0147). Overall, QBLM up to 3% in European seabass diets did not notably enhance the fatty acid profile or the functional capacity of the fillets. However, it did not show any detrimental effects, particularly in the liver. Thus, further research is warranted for framing QBL reusing and its potential in animal feeds.