Reproductive performance in male European sea bass (Dicentrarchus labrax, L.) fed two PUFA-enriched experimental diets:: a comparison with males fed a wet diet

Reproductive performance of male European sea bass (Dicentrarchus labrax) fed a wet diet (WD) was compared to that of fish fed two commercial pelleted diet enriched with polyunsaturated fatty acids (PUFAs) by the use of Northern hemisphere fish oil (ST) or tuna orbital oil (RO). Broodstock growth, spermiation duration, milt production, milt spermatozoa density, sperm motility, milt lipid composition, and fertilization rates were compared during the reproductive season. RO and ST males exhibited longer spermiation periods producing statistically higher milt volumes and milt spermatozoa densities as compared to WD; no differences in quality or motility of sperm were observed between groups. Although the fertilization rates of RO, ST and WD milt at 3 and 24 h after fertilization were similar (88-90%), significantly higher rates of embryonic and larval survival were observed at 48 and 72 h after fertilization from eggs fertilized with ST (13.9% and 15.5%) and RO milt (20.9% and 20.6%) as compared to WD (1.0% and 1.2%). Analysis of milt PUFA profiles revealed several differences between groups. Although total PUFAs wereincreased in all groups as compared to diet PUFA composition, a greater increase was noted for ST and RO. In January and March, fish fed the WD exhibited more weight gain and attained significantly higher weights, respectively, than RO fish. Results showed that although fish fed the WD displayed increased weight gain, reproductive performance was enhanced in males fed the commercially fabricated diets possibly reflecting benefits of PUFA-enrichment. (C) 2001 Elsevier Science B.V. All rights reserved.