Effects of dietary n-3 and n-6 fatty acids levels on egg and larval quality of Eurasian perch by Émilie HENROTTE (1), Julia Lynne OVERTON (2) & Patrick KESTEMONT (1) ABSTRACT. - Three groups of 40 perch breeders were reared in order to study the effects of 3 different levels of dietary n-3 and n-6 fatty acids on egg quality. Two experimental diets, R1 and R2 (n-3/n-6 = 0.13 and 35.54, respectively), were compared to one commercial food, R3 (n-3/n-6 = 3.48). Spawning and fertilization rates were high for diets R1 and R3, which displayed a n-3/n-6 ratio of 0.77 and 2.34 in the eggs, respectively, by comparison with R2 (n-3/n-6 = 4.87), which produced low reproductive performances. We can conclude that dietary n-3 and n-6 FA levels inuence egg and larval quality of Eurasian perch. Key words. - Perca uviatilis - Egg quality - Fatty acids. Cybium 2008, 32(2) suppl.: 271-272. (1) The University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium. [emilie.henrotte@fundp.ac.be] (2) Danish Institute of Fisheries Research, Dept. Aquaculture and Marine Ecology, Kavalergården 6, 2920 Charlottenlund, Denmark. Introduction One of the major constraints for the development of Eur- asian perch culture is the supply of good quality eggs. The importance of 3 fatty acids (FAs; docosahexaenoic (22:6n-3; DHA), eicosapentaenoic (20:5n-3; EPA) and arachidonic (20:4n-6; ARA) acids) in the reproduction and egg quality has been demonstrated (Bell et al., 1997). As a result of chemical similarities among these particular FAs, leading to competitive interactions, the optimal requirement for each individual FA is difficult to assess. The objective of this study was to determine the FA composition of eggs obtained from broodstock fed different n-3 and n-6 FAs levels in rela- tion with reproductive performances, egg quality and larval robustness. Methods Three groups of 40 perch breeders were reared in order to test different levels of dietary n-3 and n-6 FAs (16% lip- ids) during 9 months (from March to November 2006). Two experimental diets, R1 and R2 (n-3/n-6 = 0.13 and 35.54, respectively), were compared to one commercial sh diet, R3 (n-3/n-6 = 3.48). Spawning and fertilization rates were checked in November, and larval robustness was evaluated by osmotic shock (1 hour in NaCl 2%, 20°C) two days after hatching. Total lipid and FAs were extracted from the eggs and tested diets. Data were compared by analysis of variance ANOVA1 (Statistica 5.5). Results and discussion The survival of broodstock was similar among the three diets. The spawning rate was high for R1 and R3 (85.7 and 73.3%, respectively) while only few spawnings were obtained for R2 (33.3%). For 12 egg strands, only one was fertilized in R2, while 38.9 and 72.7% of the spawnings were fertilized in R1 and R3, respectively, with similar fertilization rates in these groups (88.6 ± 10.4 and 87.4 ± 15.1%). Larval robust- ness was comparable between R1 and R3 (74.2 ± 25.0% and 69.0 ± 24.2% survival, respectively). The present results show the same relationship between sh diet and FA compo- sition of the eggs produced. R1 and R3 displayed a n-3/n-6 ratio of 0.77 and 2.34 in the eggs respectively, while the spawnings obtained for R2 displayed a ratio of 4.87 (Tab. I), which can be correlated to low reproductive performances, specically regarding the spawning rate, but also regarding the percentage of fertilized spawnings. Our results indicate that the spawning quality of perch is directly affected by the n-6 FA content of broodstock diet. As opposed to mammal cells, which contain essentially n-6 FAs in their PUFA, sh cells contain a high level of EPA and DHA, and, consequent- ly, need those FAs in their diet. However, despite the elevat- ed levels of EPA and DHA, ARA is the chief precursor of the eicosanoids, generating 2-series prostanoids (Lands, 1989), which may act on the induction process of the ovulation as well as on spawning. Conclusion It is possible to improve the reproductive performances as well as the egg and larval quality in Eurasian perch by manipulating the fatty acid composition of the broodstock diet. Acknowledgements. - This work was support by the European Union CRAFT Percatech project (COOPT-CT-2004-512629) and by a FRIA grant. Table I. - Fatty acid composition of eggs of Eurasian perch (% of total FAs). Signicant differences (p < 0.05) are indicated with different letters. References BELL J.G., FARNDALE B.M., BRUCE M.P., NAVAS J.M. & M. CARILLO, 1997. - Effects of broodstock dietary lipid on fatty acid compositions of eggs from sea bass (Dicentrarchus labrax). Aquaculture, 149: 107-119. LANDS, W.E.M., 1989. - Differences in n-3 and n-6 eicosanoid precursor. In: Advances in prostaglandin, thromboxane and leu- kotriene research (Samuelsson B., Wong P.Y.K. & F.F. Sun, eds), pp. 602-605. New York: Raven Press. Eurasian perch egg and larval quality He n r o t t e e t a l . 272 Cybium 2008, 32(2) suppl. . Effects of dietary n-3 and n-6 fatty acids levels on egg and larval quality of Eurasian perch by Émilie HENROTTE (1), Julia Lynne OVERTON (2) & Patrick KESTEMONT (1) ABSTRACT groups of 40 perch breeders were reared in order to study the effects of 3 different levels of dietary n-3 and n-6 fatty acids on egg quality. Two experimental diets, R1 and R2 (n-3/ n-6 = 0.13 and. by comparison with R2 (n-3/ n-6 = 4.87), which produced low reproductive performances. We can conclude that dietary n-3 and n-6 FA levels inuence egg and larval quality of Eurasian perch. Key