A promising mix of protein sources obtained from biorefinery as partial replacement of dietary ingredients in aquafeed for gilthead sea bream (Sparus aurata) broodstock.

There is an increased research activity focusing on new protein and oil sources able to secure the sustainability of aquaculture productions. The factors that mainly limit the replacement of fishmeal and fish oil with alternative ingredients are their lack of essential amino acids and in long chain-polyunsaturated fatty acids (LC-PUFA). In particular, a balanced diet is necessary for broodstock, to guarantee the adequate development of brain and larval tissues and reproductive performance. The aim of this study is the evaluation of the reproductive performance of gilthead seabream broodstock (Sparus aurata) fed on experimental diets based on innovative and valuable ingredients produced utilizing aquaculture wastewater and fish processing wastes. To date, no data are available on the potential inclusion of such ingredients coming from biorefinery as fish and plant-based ingredients substitution in broodstock aquafeed. A control diet (CONTR) was prepared using a blend of conventional protein sources while an experimental diet (H1) was prepared using a mix of alternative and valuable ingredients (microalgae, Nannochloropsis sp; duckweed, Lemna minor; insects, Hermetia illucens and macroalgae, Alaria esculenta) as a partial replacement (10%) of fishmeal and vegetable protein sources. Gilthead seabream broodstock (male weight average 0.512±0.087kg and female weight average 2.522±0.34kg) were randomly allocated in circle-shaped 5000-L-fiberglass tanks, (22 fish/tank, 15 males and 7 females) in a RAS, under controlled rearing conditions, and nutritionally challenged for 6 months, 2 months before pre- and 4 months post-spawning. Being the alternative ingredients produced using aquaculture waste, diets were evaluated at nutritional, chemical and microbiological levels No contaminants were found in the diets, which resulted similar in their proximate composition and fatty acids and amino-acids profile, except for the Docosahexaenoic acid (DHA), for which H1 diets resulted more enriched respect to the control (CONTR). Spawning quality parameters were significantly different between H1 and CONTR broodstock (p < 0.05). In particular, the mix inclusion seems positively affect the hatching parameter and larval survival at 6 days posthatch (p < 0.05). No alterations in terms of skeletogenesis, gut, and muscle development were found in larvae sampled from H1 with respect to CONTR group. Further studies are underway to verify the health parameters of the broodstock.