Ovary and egg fatty acid composition of greater amberjack broodstock (Seriola dumerili) fed different dietary fatty acids profiles

Abstract

The aim of this study was to assess the effect of an experimental diet (ED), with high levels of 18:1 n-9 and low eicosapentaenoic to arachidonic acid ratio (EPA/AA), on the fatty acid (FA) profile of ovary and eggs of Seriola dumerili broodstock, in contrast to a non-specific commercial diet (nsCD), taking wild fish lipid composition as a positive reference. Two groups of Seriola broodstock born in captivity were fed with either the ED or the nsCD during two consecutive spawning seasons (21 months). After 7 months of feeding, fish fed the ED displayed an ovary FA profile much closer to wild fish. During the second spawning season, only the group fed ED released eggs. Egg FA composition showed some minor changes throughout the spawning season, with a marginal reduction of EPA in the late season being the most striking variation. Overall, the use of the ED showed some positive results, which could favor spontaneous egg release from females born in captivity. However, the lack of fertilization and the high level of 18:2 n-6 in the ovary tissue and eggs indicate that further improvements are needed in S. dumerili broodstock diet formulation in order to enhance the reproductive performance of this species in captivity.Practical applications: The use of the ED resulted in an ovary fatty acid profile of cultured females that better resembles that of wild fish. Using broodstock diets with balanced EPA/AA ratios (close to wild fish) may have a positive effect on fish broodstock reproductive performance, at least for this species.

Comparative Study of Reproductive Development in Wild and Captive-Reared Greater Amberjack Seriola dumerili (Risso, 1810)

“…The dietary deficiency of ARA and DHA also decreased tissue ARA/EPA and DHA/EPA physiological balances. Similar results related to dietary fatty acid inputs have been reported in several tissues of captive and wild white seabream ( Diplodus sargus ), black seabream ( Spondyliosoma cantharus ), yellowtail ( Seriola lalandi ) and females of greater amberjack at spawning [31, 32, 113–115]. Studies by Asturiano et al [36] showed that male European sea bass Dicentrarchus labrax fed commercial diets enriched in highly unsaturated fatty acids (HUFA) such as DHA and EPA, exhibited more successful reproductive performance in terms of duration of spermiation, total milt production, milt spermatozoa density, and fertilization than fish fed with a non-enriched diet.…”

“…Other phospholipids, including PC, contain high levels of DHA, which is the most relevant essential fatty acid in egg quality [107]. The importance of PC, PE and n-3 HUFA, as well as of DHA/EPA/ARA ratios on gonad development and egg quality has been highlighted by many authors [31, 32, 33–35, 121–124]. In fact, two thirds of the lipid fraction in vitellogenin is made of PC [107] that is also the main phospholipid in mature ovaries and fertilised eggs [125].…”

“…However, so far no comparative study of the reproductive function of wild vs captive-reared greater amberjack has been conducted, in order to identify the extent and the points at which possible reproductive impairments occur in captivity. Moreover, although few studies exist on greater amberjack female gonad biochemical composition [31, 32], no information is available on male specimens, even though a close relationship between gonad composition–and more generally fish nutritional state- and reproductive success has been demonstrated widely [33–41]. More specifically, dietary fatty acids have proven to be very important in the reproduction of several fish species, including greater amberjack, since they determine gonad composition, affecting not only sperm and egg quality [31, 32, 37, 42–44], but also being involved in the synthesis of eicosanoids that are autocrine mediators in the reproductive process [38, 45–49].…”

“…Moreover, although few studies exist on greater amberjack female gonad biochemical composition [31, 32], no information is available on male specimens, even though a close relationship between gonad composition–and more generally fish nutritional state- and reproductive success has been demonstrated widely [33–41]. More specifically, dietary fatty acids have proven to be very important in the reproduction of several fish species, including greater amberjack, since they determine gonad composition, affecting not only sperm and egg quality [31, 32, 37, 42–44], but also being involved in the synthesis of eicosanoids that are autocrine mediators in the reproductive process [38, 45–49]. Furthermore, the peptide hormone leptin plays a role in conveying signals of the energy stores to the central nervous system [50–55] and acts as a permissive factor for the onset of energy demanding processes such as reproduction [40, 56].…”

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“…Overall, females at prespawning stage presented higher lipid content in all sampled tissues, with a marked increase in dorsal muscle. Dorsal muscle lipid content was higher in our samples (24.04%) when compared to the results found in the muscle of S. fasciata at the same maturation stage (Nogueira et al, 2016) and of S. dumerilli (Haouas, Zayene, Guerbej, Hammami, & Achour, 2010;Rodríguez-Barreto et al, 2012), but similar to those found by Rodríguez-Barreto et al (2014) in indoor cultivated S. dumerilli. Such differences highlight the need of knowing fish nutritional value, especially when fish are not easy to distinguish, as is the case between Almaco jack adults and greater amberjack juveniles.…”