Influence of broodstock gilthead seabream (Sparus aurata L.) dietary fattyacids on egg quality and egg fatty acid composition throughout the spawning season

The influence of broodstock dietary lipids on egg quality and egg fatty aci d composition throughout the spawning season of gilthead seabream was inves tigated For this purpose, the fish were fed for 7 months either a control d iet (diet C) or a diet deficient in n - 3 highly unsaturated fatty acids (n - 3 HUFA) but rich in both oleic (18:1n - 9) and linolenic (18:3n - 3) aci ds (diet D). Eggs spawned by both groups of fish were sampled at the beginn ing, middle and end of the spawning season and the fatty acid composition o f their neutral (NL) and polar lipids (PL) determined. In the early season, percentages of fertilized and hatched eggs, relative proportions of NL and PL as well as their fatty acid compositions, were not affected by the lipi d composition of the broodstock diet. However, the eggs spawned during the middle and late seasons showed marked differences among the two groups of f ish, clearly reflecting the influence of dietary fatty acids. This influenc e was more evident in the neutral lipid fraction than in the polar Lipids. No correlation was found between the number of buoyant eggs and eicosapenta enoic (20:5n - 3, EPA), docosahexaenoic (22:6n - 3, DHA) fatty acids or tot al n - 3 HUFA contents in egg phospholipids. However, a negative correlatio n was detected when percentages of fertilized eggs were compared with the l evels of 18:1n - 9, 18:3n - 3 and with the ratio 18:1n - 9/n - 3 HUFA prese nt in the phospholipids. Our results indicate the importance of maintaining not only the level of n-3 HUFA in egg membrane phospholipids, but also the balance between n - 3 HUFA and other fatty acids such as 18:1n - 9 and 18: 3n - 3, in order to obtain a high spawning quality. (C) 1999 Elsevier Scien ce B.V. All rights reserved.