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Camelina and chia oils are among the vegetable oils (VOs) with high content of α‐linolenic acid (ALA) and a combination of antioxidants, giving them nutritional advantage over other VOs used in aquafeeds. The present study evaluated the effects of dietary substitution of fish oil with oils from camelina or chia on the growth performance, fatty acid (FA) composition, gene expression and blood haematology in gilthead sea bream after a 90‐day feeding trial. Five isoproteic and isolipidic diets were formulated in which fish oil was 100% (camelina oil, CSO diet; and chia oil, CO diet) or 60% (MIX1 and MIX2 diets containing camelina and chia oils, respectively) replaced with camelina or chia oils. Growth performance and FA profiles of fish were significantly affected by the dietary treatments (p <.05). Contents of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (ARA) decreased, whereas n‐3 polyunsaturated fatty acid (PUFA) and n‐3/n‐6 ratio increased in fish fed diets containing oils from camelina or chia. An up‐regulation in the expression of genes involved in PUFA metabolism and the subsequent in vivo bioconversion of precursor FAs into highly unsaturated fatty acid (HUFA, C ≥ 20 and n ≥ 3) were recorded in fish fed VO‐based diets. Red blood cells (RBC), white blood cells (WBC), haemoglobin and haematocrit did not differ among fish fed the experimental diets. Our overall results suggested that replacement of fish oil with camelina or chia oil did not adversely affect growth performance in gilthead sea bream, except for those fed CSO diet. Our results also demonstrate that fatty acid profile of fish can be modified by the dietary inclusion level of camelina or chia oils. [ABSTRACT FROM AUTHOR]

In previous studies, combined inclusion of Zn, Mn and Se in early weaning diets improved larval growth, but suggested a potential toxicity by one of these elements. The present study aimed to determine the effect of the single inclusion of Zn, Mn, Se or Cu, their combination (Control+) or their absence (Control−) on larval diets. At the end of the trial, survival was significantly (p <.05) lowest in fish fed C+ diet (17.16 ± 7% mean ± SD), followed by that of larvae fed Mn diet (21.91 ± 7%). The highest survival was obtained by Cu diet (35.27 ± 15%), followed by C− diet (34.58 ± 9%). Cu and Se supplementation significantly improved total length and body weight, in comparison with the C− fish. On the contrary, fish fed Mn and C+ showed the lowest growth. Supplementation with Zn or Cu significantly increased CuZnsod, whereas gpx was significantly upregulated in fish fed Se and C+ diets. ARA/EPA level was significantly highest and DHA/EPA lowest in larvae fed the Cu diet in fish fed C+ diet. The results pointed out the importance of supplementation with Cu, as well as Se and Zn, on early weaning diets for gilthead sea bream, and the potential toxic effect of Mn. [ABSTRACT FROM AUTHOR]

Replacement of fish meal (FM) and oil (FO) by plant sources can alter the feed mineral profile. However, requirements of these nutrients have not been established for gilthead sea bream. The aim of the present study was to obtain information about the adequate levels of some of these minerals (such as Zn, Cu, Mn, Se, Co, Fe and Ca) in diets with low FM and FO levels. Six plant‐based practical diets were supplemented with increasing levels of a multi‐nutrient package for 155 days. Performance parameters, biochemical analyses of whole body, vertebrae, plasma and blood cells; haematocrit; expression of several genes in liver and vertebrae were conducted. Increasing multi‐nutrient package affected fish growth, expression of molecular markers and mineral content in different tissues. A regression method was used to establish a relation between multi‐nutrient package levels and different indicators. However, nutrient interactions made it difficult to obtain clear results and so specific effects of each mineral must be studied in more detail. Mineral supplementation was required for Zn, Cu, Mn, Se and Co, whilst basal levels of Ca were sufficient to cover the optimum levels. On the other hand, there is evidence regarding a possible interaction between Fe and Zn which reduced Fe availability and absorption. [ABSTRACT FROM AUTHOR]

Substitution of marine ingredients (FM‐FO) by plant protein and oil sources can modify selenium (Se) levels in feeds. Se plays an important role in the antioxidative defence by forming part of selenoproteins. Se requirements of gilthead sea bream are not accurately determined; therefore, this study was conducted to define Se supplementation levels in low FM‐FO practical diets for sea bream fingerlings. A plant‐based diet containing 0.45 mg Se/kg diet was used as the basal diet. Four other diets were supplemented to contain 0.68, 0.86, 1.00 or 1.70 mg Se/kg diet, supplied as sodium selenite. Sea bream, weighing 12.6 ± 1.4 g, were distributed in triplicate groups per diet and fed for 42 days. Se supplementation up to 1.00 mg Se/kg significantly improved the growth of sea bream, whereas further increase up to 1.70 mg Se/kg diet reduced growth. The results of this study suggest that the optimum dietary levels of sodium selenite in diets with low FM‐FO with basal levels of 0.45 mg Se/kg are around 0.94 mg Se/kg to promote growth of gilthead sea bream juveniles. On the contrary, dietary levels of 1.70 mg Se/kg were found to be excessive and caused growth reduction, increased catalase expression and hydropic degeneration in the liver. [ABSTRACT FROM AUTHOR]

Experimental diets were formulated to evaluate a "pure" poultry meat meal (PMM) source in diets formulated for juvenile gilthead sea bream (Sparus aurata L.). The digestible protein contribution of fish meal in a control diet was substituted by 25%, 50% and 75% of a processed poultry meat meal (PMM) on a digestible crude protein (DCP) basis and by 5% and 10% for an enzyme‐treated feather meal (EFM) and also a spray‐dried haemaglobin meal (SDHM), respectively. In a consecutive trial, diets were designed to assess the value of a "pure" (defatted) poultry protein substituting the fish meal (FM) protein content. Experimental diets included: a control diet, two test diets where 75% of FM was replaced by a full‐fat PMM (PMM75) or a defatted grade of PMM (dPMM75) and two test diets where 50% of FM was substituted for defatted PMM (dPMM50) or a 50:50 blend of soya bean meal and defatted PMM (SBM/dPMM) to produce a composite product. This soya bean/dPMM blend was tested to enhance the nutritional value of this key plant ingredient commonly employed in sea bream diets that can be deficient in specific amino acids and minerals. In the first trial, gilthead sea bream grew effectively on diets containing up to the 75% replacement of FM attaining a mean weight of 63.6 g compared to 67.8 g for the FM control fed group. For the consecutive trial, the fishmeal‐based control diet yielded the highest SGR followed by dPMM50 and SBM/dPMM blend inclusion but was not significant. Carcass FA profiles of gilthead sea bream conformed to the expected changes in relation to the dietary FA patterns, with the 18:1n‐9 representative of the poultry lipid signature becoming more apparent with PMM inclusion. The ratio of n‐3/n‐6 fatty acids was greatly affected in sea bream fed the full‐fat PMM at 75% inclusion due to fish oil exclusion. Defatted dPMM, however, allowed more of the fish oil to be used in the diet and reducing this latter effect in sea bream carcass, hence restoring the higher total omega‐3 HUFA fatty acids namely EPA and DHA and n‐3/n‐6 ratio. It is concluded that poultry meat meal can be modestly incorporated into formulated diets for sea bream and can be used in conjunction with soya bean meal without any fundamental changes in performance and feed efficiency. [ABSTRACT FROM AUTHOR]

European fish farming drives the development of sustainable marine fish feed where marine ingredients are replaced by alternatives such as plant meals and vegetable oils. A new scenario emerges where noncurrent and/or new contaminants enter into the fish food chain as potential food safety and/or welfare concerns. Novel analytical methodologies must be developed to assess the large variety of contaminants from different families in feed ingredients, feeds based on these ingredients and fish farmed on the novel feeds. Of the novel contaminants identified in feed ingredients and feeds, the pesticides, such as chlorpyrifos‐methyl, pirimiphos‐methyl, boscalid and azoxystrobin, and the mycotoxins, such as deoxynivalenol and fumonisins (B1 + B2 + B3), were detected. Polyaromatic hydrocarbons, especially those with ≤4 ring, were found in all samples. Information of the transfer of contaminants from feed to public foodstuffs is essential for an appropriate human risk assessment of feed contaminants as well as for the harmonization of legislation of contaminants throughout the aquaculture production chain. However, the pesticides and mycotoxins found in feed were not detected in fish fillet, and hence, no transfer factor could be established. As a result, no apparent risk seems to be associated with these contaminants in fish fillets at the current background exposure levels by feeds. Recent achievements in aquafeeds with marine fish oil and fish meal below 10% represented food safety risks considerably reduced. The use of plant‐based diets implies that POPs were not found. Polar pesticides and mycotoxins were not transferred to edible fillets while PAHs were widely found in both feed and fillets. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effects of increasing docosahexaenoic acid ( DHA) levels in Sparus aurata diets supplemented with antioxidants vitamins (vitamins C and E). Six isoproteic and isolipidic formulated diets, which varied in the DHA content (38-78 g kg−1 TFA), were fed to 19 dph S. aurata larvae. No significant differences were found in survival rates or growth, which indicates that all the diets covered the minimum essential fatty acid requirements of this species. Stress resistance was not negatively affected by dietary DHA contents. In agreement, two biomarkers of the oxidative stress of the fish and the gene expression of superoxide dismutase and glutathione peroxidase were not affected by the elevation of dietary DHA, denoting that fish were sufficiently protected from oxidative damage even at high dietary DHA contents. The elevation of dietary DHA did affect neither the occurrence of skeletal malformations nor the expression of osteological markers such as run-related transcription factor 2 or alkaline phosphatase. The results of this study have confirmed that increase of the dietary DHA levels in gilthead sea bream diets does not negatively affect larval performance if the larvae are protected from peroxidation risks. Despite not being harmful, increase of DHA over the recommended requirements does not have any significant improvement in larval performance. [ABSTRACT FROM AUTHOR]

NADPH produced in the pentose phosphate pathway ( PPP) plays a central role in the reductive biosynthesis of membrane lipids, as well as in the maintenance of cell integrity; also, it has a key part in the synthesis of protein, the other member element. For that NADPH is involved in the growth processes. Our main objective is to study the effects of maslinic acid ( MA) on kinetics and its molecular nature of NADPH-generating systems in the gilthead sea bream ( S. aurata) as well as the possible changes of these enzymes related with several feeding conditions; for this, we have studied the kinetic and expression levels of glucose 6-phosphate dehydrogenase (G6 PDH), 6-phosphogluconate dehydrogenase (6 PGDH), both PPP enzymes, in liver and white muscle. MA, a triterpene, stimulates growth, protein turnover rates and hyperplasia in fish. G6 PDH and 6 PGDH showed hyperbolic kinetics under all experimental conditions. With MA feeding, the specific activity, maximum velocity and catalytic efficiency of both enzymes increased in both tissue. The Michaelis constant changed with MA and fixed diet, and these changes being in relation to the substrate affinity. Moreover, we found that MA increased the protein levels studied, and this behaviour being consistent with the regulation of the number of enzyme molecules. These results show that G6 PDH and 6 PGDH are two inducible enzymes regulated by MA. Our findings corroborate that MA affect to the activity and expression of G6 PDH and 6 PGDH, confirming its role as markers of growth. [ABSTRACT FROM AUTHOR]

The effects of steam pelleting or extrusion of a commercial feed on performance of 2 g (small) and 40 g (large) gilthead sea bream was studied. In addition the apparent digestibility of diets, gastric evacuation time (GET) and trypsin and amylase activities were measured in large fish. Fish size significantly increased protein and energy productive value, body protein and lipid, liver glycogen and liver lipid, however decreased daily growth index, feed intake and feed utilization, body moisture and hepatosomatic index. Extrusion processing decreased feed intake, more strongly for small fish, and increased daily growth index, feed utilization, protein and energy productive value, body protein and lipid. Digestibility of starch and energy increased with extrusion and GET of extruded feed was double that of steam-pelleted conditioned feed (i.e. 544 min versus 284 min). Digestive enzyme activities approached maximum values after 240 min for the pelleted diet, while those of the extruded continued to increase, at higher rates for amylase than trypsin. Pelleted diet indicated higher moisture for stomach digesta, while the moisture of the intestinal precipitate indicated a higher water-binding capacity for the extruded diet. The overall results indicate a better assimilation of the extruded diet, which could result from its prolonged gastric evacuation. [ABSTRACT FROM AUTHOR]

Juvenile gilthead sea bream (initial body weight ca. 100 g) were reared in an indoor flow through marine water system for 1 year. Fish were fed two isoenergetic [19.2 kJ g−1 dry matter (DM)] and isoproteic (426 g kg−1 DM) diets either based on fish meal (diet FM) or on a mixture of plant protein sources (diet PP), replacing 75% of fish meal protein. The growth trial was conducted in duplicate, two tanks for each dietary treatment. Growth performance and feed utilization were registered. Fillet quality parameters were evaluated and sensory analyses on cooked fillet were performed. Both groups had similar weight gain and specific growth rates. Feed intake was higher in sea bream fed diet FM (0.48 versus 0.44), while feed efficiency and protein efficiency ratio were significantly higher in sea bream fed PP (0.83 versus 0.77 and 2.0 versus 1.76, respectively). Sea bream fed diet FM had a lower hepatosomatic index (0.80 versus 0.87%), and a higher fillet yield (45.9 versus 44.9%). The fillet from sea bream fed diet FM had higher moisture (696 versus 682 g kg−1), lower lipid levels (91 versus 100 g kg−1) with higher levels of n-3 polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA), while the PP fed sea bream presented a higher level of PUFA n-6. There were minor differences in muscle free amino acid levels between the two diet groups. As regards sensory evaluation of cooked fillet, the judges were unable to discriminate the two dietary groups of fish. Summarizing, the results demonstrate the possibility to use diets containing high levels (750 g kg−1) of plant ingredients in gilthead sea bream without affecting growth performance and with minor effects on quality traits of commercial size sea bream. [ABSTRACT FROM AUTHOR]

We have studied the effects of time-restricted food access and ration restriction on gilthead sea bream demand-feeding behaviour and nutritional use of the diet ( Sparus aurata), and also compared the nutritional efficiency of three different feeding systems: manual, automatic and modulated-automatic. In the first trial, fish were allowed to feed from self-feeders under three different conditions: ad libitum, ration restriction, and time-restricted food access, and their demand-feeding pattern, diet utilization and body composition were analysed. In the second trial, animals were fed by hand or using an automatic system, either fixed or modulated, and diet utilization and body composition were analysed as before. Restricting the amount of food modifies gilthead seabream self-feeding behaviour, with fish increasing the number of demands provided these are rewarded with food. However, demand-feeding activity does not increase if rewards are restricted to a certain time. Feeding gilthead sea bream by hand versus automatically, and distributing the daily food ration in two or three equal or unequal-size daily meals, have no effect on the animals’ growth, nutritional use of the diet or body composition. [ABSTRACT FROM AUTHOR]

A feeding trial evaluated the influences of different cycles of starvation and refeeding protocols for 7 weeks on growth and feed intake in 14-g gilthead sea bream, Sparus aurata. Following 7 weeks of alternated cycles, all the groups were fed to apparent satiation for a further 3 weeks. Three groups of fish were fasted for 2, 4 or 7 days (S2, S4 and S7, respectively) and then refed until their relative feed intake differed by less than 20% of fed controls until the end of the week 7, while a fourth group (S7/Rf14) experienced three cycles, each consisting of 1 week of food deprivation followed by 2 weeks of satiation feeding. Control (C) fish were fed to satiation throughout the trial. The fish were fed a sea bream diet (450 g kg−1 crude protein) according to the protocols, twice a day for 7 weeks. Growth performance and feed intake in continuously fed control group were significantly higher than those of the deprived groups (S2, S4, S7 and S7/Rf14) ( P < 0.05). Weight gain highly correlated with total feed intake ( R2 = 94), and feed efficiency was the highest in the control group than other deprived groups ( P < 0.05). The juveniles of gilthead sea bream demonstrated only a partial compensation during the cycling period and even after being fed to satiation for another 3 weeks. The convergence of growth trajectories and subsequent hyperphagic responses of the groups fed according to protocols are discussed in terms of possible costs of compensatory growth. [ABSTRACT FROM AUTHOR]

We have studied how the diet energy level affects gilthead sea bream ( Sparus aurata) daily pattern of demand-feeding activity and nutritional use of the diet under summer- and winter-like conditions. To that end, animals were kept in a closed circuit under controlled temperature and photoperiod, and fed one of two commercial diets with either high (H: 238 g kg−1 fat) or low (L: 172 g kg−1 fat) energy content. In summer conditions (26 °C; 12 : 12 L : D), both diets yielded similar growth rate (0.7 ± 0.0 and 0.7 ± 0.1) and thermal unit growth coefficient values (0.6 ± 0.0 and 0.6 ± 0.0), and although the daily rate of delivered feed was somewhat higher for fish under the high-energy diet (16 ± 2 g kg−1 of fish) the difference was not significant. In winter conditions (17 °C; 9 : 15 L : D), on the other hand, no differences were found for any of the parameters evaluated. Thus, the higher lipid content of the diet does not appear to have any protein sparing effect. The ‘summer’ demand-feeding pattern displayed three daily peaks, which were quite apparent for fish under the low-energy diet, but rather smoothed for those that ate the energy-rich diet. This profile was replaced in winter conditions by a single peak around noon, and the animals also displayed a lower overall number of demands. [ABSTRACT FROM AUTHOR]