BROODSTOCK NUTRITIONAL PROGRAMMING: INFLUENCE OF BROODSTOCK SELECTION (HIGH OR LOW fads2) AND DIETARY FATTY ACID PROFILES ON REPRODUCTIVE PERFORMANCE AND EGG QUALITY IN GILTHEAD SEA BREAM Sparus aurata

Marine teleosts are recognised to have limited capacity of bioconversion of 18 carbon fatty acids from vegetable oils (VO) into long-chain polyunsaturated fatty acids (LC-PUFA) such as arachidonic (ARA, 20:4n-6), eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic (DHA, 22:6n-3) acids. This is mainly attributed to the low activity of Δ6 fatty acid desaturase (FADS2), a key enzyme in n-3 LC-PUFA biosynthesis. Feeding gilthead seabream broodstock with diets containing linseed oil up to 60% did not adversely affect reproductive performance, egg and larval quality. The larvae produced were found to better utilise diets with low fish meal (FM) and fish oil (FO) levels with even a long-term persistent effect on the utilisation of such low FM/FO diets by 16 month old juveniles.

The present study assessed the interaction between broodstock selection and dietary fatty acid profiles in gilthead seabream. Our aim was thus to determine the potential of nutritional programming and its interaction with the selection of broodstock with either high (H) or low (L) expression of fads2 gene on reproductive performance and its offspring's ability to utilise feeds rich in plant protein and oil sources. Gilthead sea bream male and female broodfish of H or L were selected and fed with either F (100% FO) diet or V (20%FO/80%VO) diet for 8 weeks period to study potential effect of nutritional programming on reproductive performance of gilthead sea bream.

During this period, the egg samples were collected regularly from all the four broodstock (HF, HV, LF and LV) groups. The spawning quality was significantly influenced by the broodstock selection (S) and dietary fatty acid (D). Total eggs, fertilized and viable eggs per spawn per kg female were significantly (P<0.05) improved in the high fads2 selected broodstock. The hatching and larval survival (3 days post hatch) rates were also significantly (P<0.05) improved in the high fads2 (HF and HV) broodstock group. This study emphasizes the strong positive effect of high fads2 selected broodstock on reproductive performance and egg quality. Further studies will address the effects of nutritional programming of broodstock on larval and juvenile growth performance and their capacity for utilisation of low FM/FO diets and assess the possible epigenetic changes in the larvae and juveniles as affected by the nutritional history of broodstock.