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The present study investigated the effects of nutritional programming through parental feeding on offspring performance and expression of selected genes related to stress resistance in a marine teleost. Gilthead seabream broodstock were fed diets containing various fish oil (FO)/vegetable oil ratios to determine their effects on offspring performance along embryogenesis, larval development and juvenile on-growing periods. Increased substitution of dietary FO by linseed oil (LO) up to 80 % LO significantly reduced the total number of eggs produced by kg per female per spawn. Moreover, at 30 d after hatching, parental feeding with increasing LO up to 80 % led to up-regulation of the fatty acyl desaturase 2 gene (fads2) that was correlated with the increase in conversion rates of related PUFA. Besides, cyclo-oxygenase 2 (cox2) and TNF-α (tnf-α) gene expression was also up-regulated by the increase in LO in broodstock diets up to 60 or 80 %, respectively. When 4-month-old offspring were challenged with diets having different levels of FO, the lowest growth was found in juveniles from broodstock fed 100 % FO. An increase in LO levels in the broodstock diet up to 60LO raised LC-PUFA levels in the juveniles, regardless of the juvenile’s diet. The results showed that it is possible to nutritionally programme gilthead seabream offspring through the modification of the fatty acid profiles of parental diets to improve the growth performance of juveniles fed low FO diets, inducing long-term changes in PUFA metabolism with up-regulation offads2expression. The present study provided the first pieces of evidence of the up-regulation of immune system-related genes in the offspring of parents fed increased FO replacement by LO.

Modern aquaculture feeds tend to contain lower levels of fish based ingredients, while increasing the content of plant ingredients. However, this may alter the vitamin profile of the feeds, leading to unbalanced vitamin supply. Requirements for several vitamins have been established for species such as carps and salmonids, but adequate levels for gilthead sea bream are yet unknown. Vitamin D is mainly involved in Ca homeostasis by regulating Ca uptake and liberation from bone intervening in bone remodeling. Fish are unable to synthesize vitamin D and so require absorbing it directly from the diet, thus, it is considered essential for fish. A practical plant-based diet containing 10% fish meal and 6% fish oil containing five levels of vitamin D3 (0.15, 0.43, 0.50, 0.55 and 0.65 mg kg− 1 or 5.8, 17.0, 20.0, 22.0 and 26.0 IU g− 1 ) were formulated to identify the optimum levels for gilthead seabream juveniles. Feeding juveniles of gilthead seabream with a range of vitamin D3 levels between 5.8 and 26.0 IU g− 1 for 70 days did not markedly alter growth. Increase dietary vitamin D3 significantly raised the liver contents in vitamin D3 in a dose-dependent manner following a potential regression. Increased dietary vitamin D3 levels up to 11.6 IU g− 1 may reduce the incidence of skeletal anomalies, particularly caudal and maxillary anomalies, whereas further elevation of dietary vitamin D3 levels increased the concentration of vitamin D3 in liver as well as skeletal anomalies in association to the up-regulation of alp and bmp2 gene expression. The occurrence of myocarditis signs in fish fed vitamin D3 levels of 20.0 IU g− 1 or more denote the toxic effects of these dietary levels. These results, together with the increased occurrence of skeletal anomalies in seabream fed the highest dietary vitamin D3 levels, suggest initial signs of hypervitaminosis D. Thus, the recommended level for vitamin D3 for gilthead seabream juveniles fed diets containing high levels of plant ingredients was suggested to be 11.6 IU g− 1.

© 2021 Lorenzo-Felipe, Shin, León-Bernabeu, Pérez-García, Zamorano, Pérez-Sánchez and Afonso-López., Fish egg quality is strongly related with the ability of the egg to be fertilized and develop a normal embryo with good survival and a lack of abnormalities. Large variations in the spawning quantity or quality impact directly in the competitiveness and sustainability of hatcheries, which create an overly large broodstock in order to satisfy the on-growing companies’ demand for undeformed fry. The present study reports, for the first time in relation to gilthead seabream, the effect of the genetic background of breeders for presence or absence of deformity on their spawning quality and the importance of considering this when creating broodstock. The spawning quality of crosses of breeders with genetic background for presence or absence of deformity (EBVdef), were evaluated during a whole spawning season, through study of the following traits: oocyte yield, fertilization rate, viability rate, hatching rate, larval survival rate, fertilized eggs, viable eggs, hatched eggs, and number of alive larvae. Breeders with a genetic background for deformity and a normal phenotype had shorter spawning periods, lower oocyte yield and, consequently, produced a lower number of alive larvae. In these two traits, the genetic background of breeders was of greater importance during intermediate spawning periods, when spawning is generally considered optimal for the industry, while environmental factors were more important at the beginning and end of the spawning season. In conclusion, these results demonstrate the importance of controlling the breeders’ genetics when creating broodstock., This work has been co-funded by three projects: PERFORMFISH project no. 727610, Consumer driven production: Integrating innovative approaches for competitive and sustainable performance across the Mediterranean aquaculture value chain (EU Horizon 2020 programme); PROGENSA III project, Mejora de la Competitividad del Sector de la Dorada a Través de la Selección Genética (JACUMAR program, European Maritime and Fisheries Fund [EMFF]); MORFOGEN project no. RTA2017-00054-C03-02, Estudio de los factores genéticos y moleculares que regulan la morfología en dorada (Sparus aurata) [Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) funded from MCIU/AEI/FEDER, UE]. Research co-financed by the Agencia Canaria de Investigación, Innovación y Sociedad de la Información de la Consejería de Economía, Industria, Comercio y Conocimiento, and by the European Social Fund (ESF) Integrated Operational Program of Canary Islands 2014–2020, Axis 3 Priority Theme 74 (85%).

The present work investigated how the combination of poultry oil with microalgae oils, rich in eicosapentaenoic acid and docosahexaenoic acid (ED diets) or n-6 docosapentaenoic acid and n-3 docosahexaenoic acid (DD diets) modulates hepatic lipid metabolism in gilthead sea bream juveniles. Diets were tested using two different fishmeal contents (15% and 7.5%) and compared against a fish oil-based diet (CTRL) and two negative control diets based on poultry oil as lipid source (PO diets). After 74 days of feeding, sea bream fed 15% FM ED or DD diets showed similar daily growth index to those fed CTRL, while those fed PO diets caused reduced growth. Fish livers reflected the highest contents in n-3 long-chain polyunsaturated fatty acids when fed CTRL, ED or DD diets, which down-regulated fas, scd-1a, fads2, lpl and cpt1, reducing hepatic lipid accumulation and hepatocytes size. In contrast, fish fed PO diets showed the lowest deposition of n-3 long-chain polyunsaturated fatty acids and the highest oleic acid in liver, leading with the highest hepatosomatic index due to increased liver lipids. Therefore, these fish revealed a severe hepatic steatosis associated with an increased expression of lipogenesis-related genes, particularly fas, lpl and sbrep1. Furthermore, PO diets seemed to activate desaturation pathways in fish livers, reflected by the highest accumulation of fatty acids that are products from desaturases and the highest fads2 and scd-1a expressions. The reduction of the dietary fishmeal content to 7.5% lowered fish growth, although hepatic lipid metabolism seemed to be more affected by FO replacement than FM replacement. Combining microalgae with poultry oil could be an alternative lipid and essential fatty acid source to fish oil in marine fish diets.

The principle aim of this study is to elucidate the relationship between the fatty acid desaturase 2 gene (fads2) expression pattern in peripheral blood cells (PBCs) and liver of gilthead seabream (GSB), Sparus aurata broodstock in order to determine the possible use of fads2 expression as a potential biomarker for the selection of broodstock. This selection could be utilized for breeding programs aiming to improve reproduction, health, and nutritional status. Passive Integrated Transponder (PIT)-tagged GSB broodstock (Male-1.22 &plusmn, 0.20 kg, 44.8 &plusmn, 2 cm and female-2.36 &plusmn, 0.64 kg, 55.1 cm) were fed a diet containing low levels of fish meal and fish oil (EPA 2.5, DHA 1.7 and n-3 LC-PUFA 4.6% TFA) for one month. After the feeding period, fads2 expression in PBCs and liver of both male and female broodstock were highly significantly correlated (r = 0.89, p &lt, 0.001). Additionally, in male broodstock, liver fads2 expression was significantly correlated (p &lt, 0.05) to liver contents in 16:0 (r = 0.95, p = 0.04) and total saturates (r = 0.97, p = 0.03) as well as to 20:3n&ndash, 6/20:2n&ndash, 6 (r = 0.98, p = 0.02) a Fads2 product/precursor ratio. Overall, we found a positive and significant correlation between fads2 expression levels in the PBCs and liver of GSB broodstock. PBCs fads2 expression levels indicate a strong potential for utilization as a non-invasive method to select animals having increased fatty acid bioconversion capability, better able to deal with diets free of fish meal and fish oil.

The negative effects of oxidative damage on larval development, growth and survival are among the factors markedly affecting marine fish larvae production success. Whereas α-tocopherol (vit E) and l -ascorbic acid (vit C) are strong antioxidants, the potential antioxidant role of taurine (Tau) in fish diets and its relation with other antioxidant nutrients needs further clarification. The present study aimed to determine the potential interactions between the dietary levels of vit E plus vit C and Tau on survival, growth, bone development and oxidative metabolism in gilthead seabream larvae. Six micro-bound diets containing two levels of Tau combined with three levels of vit E plus vit C were manually fed 24 times/day to 16 dph larvae for 15 days. Elevation of dietary vit E and vit C over 3000 mg/kg, led to unbalanced body vit C/vit E ratio and up-regulation of genes coding for antioxidant enzymes, the highest incidence of bone anomalies and the lowest larval survival. Increase in dietary vit C + vit E up to 1800 mg/kg, down-regulated GPX expression, up-regulated OC expression and reduced maxillary bone anomalies. Increase in dietary Tau up to 7.1 g/kg significantly improved larval growth, down-regulated antioxidant enzyme genes and reduced the incidence of bone anomalies. Moreover, the pro-oxidative effects of the high supplementation of vit C and E where mitigated by increase in dietary Tau levels. Finally, increase in dietary vit E, vit C and Tau up to 1783 mg/kg, 1921 mg/kg and 7 g/kg lead to the highest larval survival and growth, the highest OC gene expression and the lowest incidence of bone anomalies, including lordosis, kyphosis, branchiostegal and maxillary bones anomalies.

Nutrition during periconception and early development can modulate metabolic routes to prepare the offspring for adverse conditions through a process known as nutritional programming. In gilthead sea bream, replacement of fish oil (FO) with linseed oil (LO) in broodstock diets improves growth in the 4-month-old offspring challenged with low-FO and low-fishmeal (FM) diets for 1 month. The present study further investigated the effects of broodstock feeding on the same offspring when they were 16 months old and were challenged for a second time with the low-FM and low-FO diet for 2 months. The results showed that replacement of parental moderate-FO feeding with LO, combined with juvenile feeding at 4 months old with low-FM and low-FO diets, significantly (Pα-linolenic acid and linoleic acid in broodstock diets lead to a significant down-regulation of hepatic lipoprotein lipase (PPn-3, 18 : 3n-6, 20 : 5n-3, 22 : 6n-3 and 22 : 5n-6. Thus, this study demonstrated the long-term nutritional programming of gilthead sea bream through broodstock feeding, the effect of feeding a ‘reminder’ diet during juvenile stages to improve utilisation of low-FM/FO diets and fish growth as well as the regulation of gene expression along the fish’s life-cycle.

The main objective of this study was to assess the effects of graded levels of replacement of fishmeal (FM) and fish oil (FO) by terrestrial meals (TM) and vegetable oils (VO) on gut health of European sea bass (Dicentrarchus labrax) based on gut morphology, gut-associated immune system (GALT) and gut microbiota composition. Reducing the dietary FM and FO levels down to 10 and 3%, respectively did not affect the growth of European sea bass. Increase in TM and VO markedly affected anterior and posterior gut morphology and fatty acid composition, which mirrored the dietary fatty acid profile. FO replacement by VO increased lipid deposition in anterior gut lamina propria, denoting an effect in lipid metabolism and lipoprotein synthesis. In posterior gut, FM replacements by TM induced an engrossment of the submucosa, an up-regulation of the proinflammatory cytokines IL-1β and TNFα genes, a relatively high mucus production and changes in mucosal microbiota profiles. Finally, supplementation of 0%FM-0%FO diets with LC-PUFA contributed to maintain gut homeostasis in terms of GALT response and microbiota profiles alterations. Statement of relevance FM and FO appropriate dietary levels for European seabass

Environmental factors such as nutritional interventions during early developmental stages affect and establish long-term metabolic changes in all animals. Diets used during the spawning period causes a nutritional programming effect in offspring of gilthead sea bream and affects long-term metabolism. Studies showed modulation of genes such as fads2 which is considered to be a rate-limiting step in the synthesis of n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA). However, it is still unknown whether this adaptation is related to the presence of precursors or limitations in the pre-formed products, n-3 LC-PUFA, contained in the diets used during nutritional programming. This study investigates the combined effects of nutritional programming through broodstock diets during the spawning period and broodfish showing higher or lower fads2 expression levels in the blood after 1-month feeding with a diet containing high levels of plant protein sources and vegetable oils (VM/VO). Broodfish showing high fads2 expression had a noticeable improvement in the spawning quality parameters as well as on the growth of 6 months old offspring when challenged with a high VM/VO diet. Further, nutritional conditioning with 18:3n-3 rich diets had an adverse effect in comparison to progeny obtained from fish fed high fish meal and fish oil (FM/FO) diets, with a reduction in growth of juveniles. Improved growth of progeny from the high fads2 broodstock combined with similar muscle fatty acid profiles is an excellent option also for tailoring and increasing the flesh n-3 LC-PUFA levels to meet the recommended dietary allowances for human consumption.

Polyunsaturated fatty acids (PUFA) in parental diets play a key role in regulating n-3 LC-PUFA metabolism of the offspring. However, it is not clear whether this metabolic regulation is driven by the precursors presented in the diet or by the parental ability to synthesize them. To elucidate this, broodstocks of gilthead sea bream with different blood expression levels of fads2, which encodes for the rate-limiting enzyme in the n-3 LC-PUFA synthesis pathway, were fed either a diet supplemented with alpha-linolenic acid (ALA, 18:3n-3) or a control diet. The progenies obtained from these four experimental groups were then challenged with a low LC-PUFA diet at the juvenile stage. Results showed that the offspring from parents with high fads2 expression presented higher growth and improved utilization of low n-3 LC-PUFA diets compared to the offspring from parents with low fads2 expression. Besides, an ALA-rich diet during the gametogenesis caused negative effects on the growth of the offspring. The epigenetic analysis demonstrated that methylation in the promoter of fads2 of the offspring was correlated with the parental fads2 expression levels and type of the broodstock diet., This work has been (partly) funded under the EU Horizon 2020 programme by the PERFORMFISH project no. 727610: Consumer driven production: Integrating innovative approaches for competitive and sustainable performance across the Mediterranean aquaculture value chain.

Fish quality traits are important criteria for consumers in the commercial market as well as growth. In this study, flesh composition and morphology traits, in comparison with growth traits, were selected to study their additive genetic variation at harvest size, and their genetic and phenotypic correlations between different environments (cage and estuary). Flesh composition was measured by NIR and FFM technologies, while morphology was carried out by using image analysis with the IMAFISH_ML software. Heritability estimates ranged from low to medium (0.08–0.40) for growth, flesh composition and morphological traits. The genetic correlations were positive and high between growth traits (weight and SGR), negative and high between moisture versus lipids, negative and low for proteins vs. moisture and lipids, and high for morphological traits. At harvest size, GxE interactions were calculated from the same families cultured in cages and estuaries. The estimations were mainly high for all traits, suggesting a priori scarce GxE interaction. In conclusion, new technological traits showed additive variation components and genetic correlations between them and with growth traits.

Manganese (Mn) is an essential metal for fish and requirements have been established for several finfish but not for gilthead sea bream. Thus, the present study aims to establish the optimal dietary supplementation level of Mn in gilthead sea bream fingerlings fed vegetable based diets. Gilthead sea bream fingerlings (weight 12.6 ± 1.5 g, mean ± S.D.) were fed five practical diets high in vegetable ingredients (fish meal: 10%, fish oil: 6%). The diets were supplemented to contain 19, 27, 30, 41 and 66 mg Mn kg−1 as MnSO4. Four hundred and fifty sea bream fingerlings were randomly distributed in 15 tanks and fed one of the five diets until apparent satiation three times per day for 42 days. Growth parameters including feed intake, thermal growth coefficient and feed conversion ratio were calculated. At the end of the trial, samples were taken for biochemical, mineral, histological and gene expression analyses. After the feeding trial, fish almost tripled their weight, but dietary Mn levels did not affect growth parameters or survival. The high fish meal substitution levels led to high Mn contents in the basal diet (19 mg Mn kg−1 diet), that seemed to be sufficient to promote sea bream growth. Body lipid composition, protein and ash were not affected by the dietary Mn. Similarly, whole body, liver and vertebrae mineral contents were not affected by Mn supplementation. Morphological characteristics of liver had no significant differences among dietary Mn levels. However, increase of Mn contents beyond 30 mg Mn kg−1 down-regulated mnsod expression. Expression of cat gene was not affected. Overall, results suggest that the Mn content present in the basal diet (19 mg Mn kg−1) was sufficient to cover the requirements in juvenile gilthead sea bream fed practical plant-based diets, although results from oxidative status markers might point out the need to increase supplementation levels beyond this point when fish are under conditions that may affect their oxidative status.

Nutritional intervention with vegetable oils (VO) supplemented to fish broodstock diets enhances progeny ability to utilize low fish meal (FM) and fish oil (FO) diets. However, the intervention with vegetable meals (VM) in broodstock diets has been scarcely tested in marine fish. This study aims to determine the effect of FM replacement by VM alone or in combination with FO replacement by VO as a programming tool. Different broodstocks of gilthead sea bream were fed one of three diets: one contained 35% FM and 10% FO, another contained VM in replacement of FM (FM: 15%) or a third one had both VM and VO in replacement of FM and FO (15% FM and 2.7% FO). At the weight of 3 g, their offspring were challenged with a low FM (5%) and FO (3%) diet for 45 days. FM replacement by VM in broodstock diets did not affect fish reproductive performance but in offspring juveniles reduced growth and feed efficiency and in liver, altered fatty acids profiles and down-regulated fatty acyl desaturase 2 (fads2) expression. Combined supplementation of VM and VO in broodstock diets led to a poor reproductive performance, reducing female fecundity and the egg content in eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). At molecular level, the expression of fads2 and target of rapamycine (tor) genes in the eggs were upregulated. Similarly, in liver of juvenile progenies fads2 and elongase of very long chain fatty acids 6 (elovl6) expression were up-regulated, whereas fads2 expression was correlated to sterol regulatory element-binding protein transcription factor 1 (srebp1). However, methylation rates of CpG rich regions in fads2 promoter were not significantly different among juvenile groups. Thus, the replacement of FM by VM, alone or in combination with FO in diets for gilthead sea bream broodstock negatively affected growth performance of juvenile offspring, whereas the replacement of FO by VO enhanced the fatty acid desaturase and elongase activities in the offspring, especially when juveniles were fed a diet with a high replacement of FM and FO by VM and VO.

The lymphocystis disease (LCD) is a viral infection with a high economic impact in gilthead sea bream aquaculture. In this study, genetic estimates associated with lymphocystis disease virus (LCDV) disease susceptibility and growth were determined in sea bream juveniles. Two fish batches (named batch 1 and batch 2) were built from mass spawning and reared under industrial conditions until disease outbreak. At the moment of the sampling (n = 500 specimens for each batch), all animals had the typical LCDV lesions in the skin. For phenotyping, animals were weighted and photographed for image analysis (surface covered and lesion intensity). LCDV DNA copies were quantified in the liver by qPCR. Batch 1 had a higher surface covered and lesion intensity than batch 2, and the body caudal region was the lowest affected region in both batches. The average LCDV DNA copies in liver were higher in the batch 1 than batch 2, and they were positively correlated with severity index (SI) categories (r2 = 0.90&ndash, 0.94). The total number of families evaluated were 150 and 128 for batch 1 and batch 2, respectively, with a high bias in offspring contribution by family and broodstock. Heritabilities for weight and length were 0.18 and 0.14 in batch 1 and 0.06 and 0.05 in batch 2, respectively. Heritability for the number of viral DNA copies was low (&lt, 0.08) in both batches. Heritabilities for SI in binary scale were 0.32/0.33 and 0.21/0.24 (underlying liability/Bayesian approach) for batch 1 and batch 2, respectively. Genetic correlations were very high and positive when growth traits (weight and length) or disease traits (LCDV DNA copies and SI) were compared. In contrast, the genetic correlations between growth and disease traits were moderate&ndash, high and positive in the batch 1 but negative in batch 2. These results indicate the genetic selection for LCDV susceptibility and growth is feasible in sea bream juveniles, although estimates are highly dependent on the age. The information provided is relevant to designing selective breeding programs in sea bream.

One of the factors that limits the replacement of fish meal (FM) and fish oil (FO) by plant ingredients in diets for marine fish, is their lack of long chain-polyunsaturated fatty acids (LC-PUFA). LC-PUFA are essential fatty acids for these fish species, which lack sufficient fatty acyl desaturase 2 (Fads2) activity to synthesize them. Nutritional programing or the use of broodstock with a higher Fads2 activity could improve marine fish ability to synthesize LC-PUFA and their ability to use low FM and FO diets. The aim of this study was to determine the effect of gilthead seabream broodstock with inherently high or inherently lowfads2gene expression and nutritional programing with broodstock diets rich in FO or rapeseed oil (RO) on the progeny growth performance, liver morphology, biochemical composition and expression of selected genes. Sea bream juveniles (2.31± 0.01g initial body weight, mean ± SD) obtained from broodstock with either high (H) or low (L)fads2expression and fed a broodstock diet based on FO or RO were randomly distributed into 12×250L tanks and nutritionally challenged for 45days with a diet containing only 7.5% FM and no FO. The highest growth was found in juveniles from broodstock with a highfads2expression and fed the RO diet, whereas the lowest growth was obtained in those from broodstock with a lowfads2expression and fed the RO diet. Juveniles from broodstock with highfads2expression showed significantly higherfads2expression in liver and increased PUFA contents in liver and muscle. Replacement of FO by RO in broodstock diets led to a significantly increased hepatic 18:3n-6/18:2n-6 ratio and reduction in the viscerosomatic index of the progeny juveniles, the hepatocyte size and theghr-1/ghr-2expression in muscle. Overall, the results showed significant trans-generational effects of both the broodstockfads2expression and the type of lipid in the broodstock diet on the metabolism and performance of the juvenile progeny challenged with a diet low in FM and FO.