Browsing by Author "Dias, Jorge"
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- A nutritional strategy to promote gilthead seabream performance under low temperaturesPublication . Teodósio, Rita; Aragão, Cláudia; Colen, R.; Carrilho, Raquel; Dias, Jorge; Engrola, SofiaGilthead seabream (Sparus aurata) is vulnerable to low water temperature, which may occur in the Southern Europe and Mediterranean region during Winter. Fish are poikilothermic animals, therefore feed intake, digestion, metabolism and ultimately growth are affected by water temperature. This study aimed to evaluate growth performance, feed utilisation, nutrient apparent digestibility, and nitrogen losses to the environment in gilthead seabream juveniles reared under low temperature (similar to 13 degrees C). Three isolipid and isoenergetic diets were formulated: a diet similar to a commercial feed (COM) that contained 44% crude protein and 27.5% fishmeal, and two experimental diets with a lower protein content of 42% (ECO and ECOSup). In both ECO diets fishmeal inclusion was reduced (10% in ECO and 7.5% in ECOSup diet) and 15% poultry meal was included. Additionally, the ECOSup diet was supplemented with a mix of feed additives intended to promote fish growth performance and feed intake. The ECO diets presented lower production costs than the COM diet, whilst incorporating more sustainable ingredients. Gilthead seabream juveniles (+/- 154.5 g initial body weight) were randomly assigned to triplicate tanks and fed the diets for 84 days. Fish fed the ECOSup diet attained a similar final body weight than fish fed the COM diet, significantly higher than fish fed the ECO diet. ECOSup fed fish presented significantly higher hepatosomatic index than COM fed fish, most likely due to higher hepatic glycogen reserves. The viscerosomatic index of ECOSup fed fish were significantly lower compared to COM fed fish, which is a positive achievement from a consumer's point of view. ECOSup diet exhibited similar nutrient digestibility than the COM diet. Moreover, feeding fish with the ECO diets resulted in lower faecal nitrogen losses when compared to COM fed fish. The results suggest that feeding gilthead seabream with an eco-friendly diet with a mix of feed additives such as the ECOSup diet, promoted growth and minimised nitrogen losses to the environment. Nutritional strategies that ultimately promote feed intake and diet utilisation are valuable tools that may help conditioning fish to sustain growth even under low temperatures.
- Alternative formulations for gilthead seabream diets: towards a more sustainable productionPublication . Aragão, Cláudia; Cabano, Miguel; Colen, R.; Fuentes, Juan; Dias, JorgeTo support the expected increase in aquaculture production during the next years, a wider range of alternative ingredients to fishmeal is needed, towards contributing to an increase in production sustainability. This study aimed to test diets formulated with non‐conventional feed ingredients on gilthead seabream (Sparus aurata) growth performance, feed utilization, apparent digestibility of nutrients and nutrient outputs to the environment. Four isonitrogenous and isoenergetic diets were formulated: a control diet (CTRL) similar to a commercial feed and three experimental diets containing, as main protein sources, plant by‐products, glutens and concentrates (PLANT); processed animal proteins (PAP); or micro/macroalgae, insect meals and yeast (EMERG). Diets were tested in triplicate during 80 days. The EMERG treatment resulted in lower fish growth performance, higher FCR and lower nutrient and energy retentions than the other treatments. The lowest protein digestibility was found for the EMERG diet, which caused increased nitrogen losses. The PLANT and PAP treatments resulted in better fish growth performance, higher nutrient and energy retentions, and lower FCR than the CTRL treatment. The significant improvement in FCR found for fish fed PLANT and PAP diets and the high protein digestibility of these diets contribute towards minimizing the environmental impacts of seabream production.
- Amino acid metabolism in gilthead seabream is affected by the dietary protein to energy ratiosPublication . Teodósio, Rita; Aragão, Cláudia; Conceicao, Luis; Dias, Jorge; Engrola, SofiaThe dietary protein to energy ratio (P/E) has proven to influence protein utilization and/or growth in several fish species. This study intended to unravel the bioavailability and metabolic fate of lysine and methionine in gilthead seabream (Sparus aurata) juveniles fed plant diets with different P/E ratios. Seabream juveniles were fed two isonitrogenous diets (45% crude protein) differing in crude lipids (20 and 14%): LowP/E (P/E ratio=20.0 mg protein kJ-1) and HighP/E (P/E ratio=21.4 mg protein kJ-1). After three weeks, fish (11.6 +/- 4.3 g) were tube-fed the respective diet labelled with C-14-protein (L-amino acid mixture), C-14-lysine, or C-14-methionine. Protein, lysine, and methionine utilization were determined based on the proportion of C-14-amino acid evacuated, retained in the free or protein-bound fraction of liver and muscle, or catabolized. This study revealed that a decrease in P/E ratio resulted in lower amino acid evacuation (p < 0.05), contributing to a more efficient amino acid uptake. Results indicate that amino acids are retained as protein in the liver and not only temporarily available in the free pool. The amount of free amino acids retained in the muscle of LowP/E fed fish was significantly higher than in HighP/E fish (p < 0.05) due to a simultaneous higher retention of lysine and methionine, without affecting the overall protein retention. Methionine catabolism was significantly lower than lysine or protein independently of the P/E ratio (p < 0.05), reinforcing that this amino acid is preferentially spared for metabolic functions and not used as energy source. In contrast, increasing the dietary P/E ratio decreased lysine catabolism and increased its availability for growth. The bioavailability and metabolism of individual amino acids should be considered when optimizing P/E ratios in diets for gilthead seabream juveniles. Formulating diets with optimum P/E ratios will improve diet utilization and fish performance.
- Can Senegalese sole post-larvae effectively grow on low dietary DHA and lipid levels during weaning?Publication . Pinto, Wilson; Engrola, S.; Santos, André; Bandarra, Narcisa M.; Dias, Jorge; Conceicao, LuisSenegalese sole (Solea senegalensis) is a highly-valuable flatfish species with interest for diversification of aquaculture in Mediterranean countries. Unlike other fish species known to have a high dietary DHA requirement during the larval stage, several studies have suggested dietary DHA could play a minor role for Senegalese sole during the early developmental stages. This suggestion was recently supported by studies that indicated an ability of Senegalese sole to biosynthesise DHA from its precursors during the larval period. However, it is still uncertain if Senegalese sole post-larvae can effectively grow on low dietary DHA levels during weaning. Moreover, recent studies focusing on the juvenile phase of Senegalese sole have suggested a possible impairment of this species to efficiently digest or absorb high dietary lipid levels. Yet, if a reduction of dietary lipid levels would affect a normal development of Senegalese sole during the early stages remains to be established. Therefore, this study aimed at determining if a reduction of dietary DHA and lipid levels would affect Senegalese sole performance and lipidme-tabolism duringweaning and post-larval period. In this study, Senegalese sole post-larvae were reared according to four dietary treatments: low lipid levels (treatments LFAT and LFAT_DHA) and moderate lipid levels (MOD-FAT and MODFAT_DHA). DHA levels in LFAT_DHA and MODFAT_DHA diets were higher than in LFAT and MOD-FAT diets, respectively. Subsequently, effects of experimental diets on Senegalese sole post-larval growth, survival, fatty acid composition and histopathological condition of intestinal and liver tissues were evaluated. Results showed that feeding on diets with low DHA and lipid levels significantly reduced the growth performance of Senegalese sole post-larvae. However, at the end of the experimental period, no significant differences were observed for post-larval survival in response to dietary treatments. In overall, this study disadvises that weaning diets for Senegalese sole post-larvae should contain low DHA and lipid levels, as a reduction of these levels may compromise post-larval growth performance.Statement of relevance: Determining essential fatty acid requirements in marine fish larvae is of utmost importance for the aquaculture industry, contributing to fulfil the growth potential of farmed species. In the case of Senegalese sole, a highly valued species farmed in Mediterranean countries, it may have the capacity to biosynthesise DHA from its precursors during the larval stage. However, the inclusion of DHA-rich oils in weaning diets is costly, considerable savings could be achieved by replacing DHA-rich oils by common fish oils in weaning diets for this species. Furthermore, Senegalese sole has also been shown a poor ability to deal with high dietary lipid levels during the juvenile stage. However, no studies have addressed this capacity in Senegalese sole larvae. This study comprises an evaluation on the effects of reducing dietary DHA and lipid levels during Senegalese sole weaning by integrating an assessment of these effects on post-larval growth, survival, fatty acid composition and histopathological condition. (C) 2016 Elsevier B.V. All rights reserved.
- Circulating small non-coding RNAs provide new insights into vitamin K nutrition and reproductive physiology in teleost fishPublication . I, Fernández; Fernandes, Jorge M. O.; Roberto, Vânia; Kopp, Martina; Oliveira, Catarina; Riesco, Marta F.; Dias, Jorge; Cox, Cymon J.; Leonor Cancela, M.; Cabrita, Elsa; Gavaia, PauloBackground: Vitamin K (VK) is a fat-soluble vitamin known for its essential role in blood coagulation, but also on other biological processes (e.g. reproduction, brain and bone development) have been recently suggested. Nevertheless, the molecular mechanisms behind its particular function on reproduction are not yet fully understood. Methods: The potential role of VK on reproduction through nutritional supplementation in Senegalese sole (Solea senegalensis) was assessed by gonadal maturation and 11-ketosterone, testosterone and estriol plasma levels when fed with control or VK supplemented (1250 mg kg(-1) of VK,) diets along a six month trial. At the end, sperm production and quality (viability and DNA fragmentation) were evaluated. Circulating small non-coding RNAs (sncRNAs) in blood plasma from males were also studied through RNA-Seq. Results: Fish fed with dietary VK supplementation had increased testosterone levels and lower sperm DNA fragmentation. SncRNAs from blood plasma were found differentially expressed when nutritional and sperm quality conditions were compared. PiR-675//676//4794//5462 and piR-74614 were found up-regulated in males fed with dietary VK supplementation. Let-7g, let-7e(18nt), let-7a-1, let-7a-3//7a-2//7a-1, let-7e(23nt) and piR-675//676//4794//5462 were found to be up-regulated and miR-146a and miR-146a-1//146a-2//146a-3 down-regulated when fish with low and high sperm DNA fragmentation were compared. Bioinformatic analyses of predicted mRNAs targeted by sncRNAs revealed the potential underlying pathways. Conclusions: VK supplementation improves fish gonad maturation and sperm quality, suggesting an unexpected and complex regulation of the nutritional status and reproductive performance through circulating sncRNAs. General significance: The use of circulating sncRNAs as reliable and less-invasive physiological biomarkers in fish nutrition and reproduction has been unveiled.
- Dietary glucose stimulus at larval stage modifies the carbohydrate metabolic pathway in gilthead seabream (Sparus aurata) juveniles: An in vivo approach using C-14-starchPublication . Rocha, Filipa; Dias, Jorge; Geurden, Inge; Dinis, Maria Teresa; Panserat, Stephane; Engrola, S.The concept of nutritional programming was investigated in order to enhance the use of dietary carbohydrates in gilthead seabream juveniles. We assessed the long-term effects of high-glucose stimuli, exerted at the larval stage, on the growth performance, nutrient digestibility and metabolic utilization and gene expression of seabream juveniles, challenged with a high-carbohydrate intake. During early development, a group of larvae (control, CTRL) were kept under a rich-protein-lipid feeding regime whereas another group (GLU) was subjected to high-glucose stimuli, delivered intermittently over time. At juvenile stage, triplicate groups (IBW: 2.5 g) from each fish nutritional background were fed a high-protein (59.4%) low-carbohydrate (2.0%) diet before being subjected to a low-protein (43.0%) high-carbohydrate (33.0%) dietary challenge for 36-days. Fish from both treatments increased by 8-fold their initial body weight, but neither growth rate, feed intake, feed and protein efficiency, nutrient retention (except lipids) nor whole-body composition were affected (P (>) 0.05) by fish early nutritional history. Nutrient digestibility was also similar among both groups. The metabolic fate of C-14-starch and C-14-amino acids tracers was estimated; GLU juveniles showed higher absorption of starch-derived glucose in the gut, suggesting an enhanced digestion of carbohydrates, while amino acid use was not affected. Moreover, glucose was less used for de novo synthesis of hepatic proteins and muscle glycogen from GLU fish (P < 0.05). Our metabolic data suggests that the early glucose stimuli may alter carbohydrate utilization in seabream juveniles. (C) 2016 Elsevier Inc. All rights reserved.
- Dietary lipid level affects growth performance and nutrient utilisation of Senegalese sole (Solea senegalensis) juvenilesPublication . Borges, Pedro; Oliveira, Beatriz; Casal, Susana; Dias, Jorge; Conceicao, Luis; Valente, Luisa M. P.Over the last few years, several aspects of Senegalese sole (Solea senegalensis) culture have been developed and optimised but the dietary lipid level for optimal growth has never been determined. Hence, five isonitrogenous diets (56 % dietary protein) with increasing dietary lipid levels (4, 8, 12, 16 and 20 % DM) were fed to satiation to triplicate groups of twenty fish (mean initial weight 10 g). Fifteen tanks were randomly assigned one of the five diets. Feed was distributed using automatic feeders, and fish were fed over a 16-week period. At the end of the experiment the fish fed on diets containing the two lowest dietary lipid levels (4 and 8 %) showed a 3-fold body-weight increase with a significantly higher daily growth index than fish fed higher lipid levels (1-2 v. 0-8). Moreover, these fish displayed a significantly lower dry feed intake (12g/kg per d) and feed conversion ratio (1-0) compared with fish fed higher lipids levels (16-19 g/kg per d; feed conversion ratio 2-0). Low dietary lipid levels (< 12 %) significantly improved nutrient retention and gain and hence growth, without major effects on whole-body composition. Despite the slight alteration in n-3 PUFA muscle content in the fish fed low-fat-diets, this fish fed low dietary lipid still remains a rich n-3 PUFA product and generally maintained its nutritional value. These results evidenced a low lipid tolerance of Senegalese sole juveniles and suggest a maximal dietary inclusion level of 8 % lipids for both optimal growth and nutrient utilisation without compromising flesh quality.
- Dietary methionine supplementation improves the European seabass (Dicentrarchus labrax) immune status following long-term feeding on fishmeal-free dietsPublication . Machado, Marina; Engrola, Sofia; Colen, R.; Conceicao, Luis E. C.; Dias, Jorge; Costas, BenjaminMethionine is a limiting amino acid (AA) in fish diets, particularly in those containing high levels of plant protein (PP), and is key in the immune system. Accordingly, outcome on the fish immune mechanisms of methionine-deficient and methionine-supplemented diets within the context of 0 % fishmeal formulation, after a short and prolonged feeding period, was studied in European seabass (Dicentrarchus labrax). For this, seabass juveniles were fed a (i) fishmeal-free diet, meeting AA requirements, but deficient in methionine (MET0·65); (ii) as control, the MET0·65 supplemented with L-methionine at 0·22 % of feed weight (CTRL); (iii) two diets, identical to MET0·65 but supplemented at 0·63 and 0·88 % of feed weight of L-methionine (MET1·25 and MET1·5, respectively); and (iv) a fishmeal-based diet (FM), as positive control. After 2 and 12 weeks of feeding, blood and plasma were sampled for leucocyte counting and humoral parameter assays and head-kidney collected for gene expression. After 2 weeks of feeding, a fishmeal-free diet supplemented with methionine led to changes in the expression of methionine- and leucocyte-related genes. A methionine immune-enhancer role was more evident after 12 weeks with an increased neutrophil percentage and a decreased expression of apoptotic genes, possibly indicating an enhancement of fish immunity by methionine dietary supplementation. Furthermore, even though CTRL and FM present similar methionine content, CTRL presented a reduced expression of several immune-related genes indicating that in a practical PP-based diet scenario, the requirement level of methionine for an optimal immune status could be higher.
- Dietary tryptophan supplementation induces a transient immune enhancement of gilthead seabream (Sparus aurata) juveniles fed fishmeal-free dietsPublication . Ramos-Pinto, Lourenco; Martos-Sitcha, Juan A.; Reis, Bruno; Azeredo, Rita; Fernandez-Boo, Sergio; Perez-Sanchez, Jaume; Alvar Calduch-Giner, Josep; Engrola, Sofia; Conceicao, Luis E. C.; Dias, Jorge; Silva, Tome S.; Costas, BenjaminEuropean aquaculture is an industry with a high sustainability profile contributing to the supply of safe seafood. However, several diseases can affect farmed fish and it is imperative to find alternatives for chemotherapeutic treatments when disease outbreaks occur. Maintenance of health through nutrition is well-establish in modern animal farming, and amino acids (AA) are promising candidates as functional additives to improve fish health. Therefore, the goal of this research is to provide a better understanding of the influence of tryptophan supplementation on nutritional condition and immune mechanisms in fish. Triplicate groups of fish (13.3 +/- 0.3g) previously fed with a fishmeal-based diet were either fed a control diet with an extreme formulation (0% fishmeal) but meeting the AA requirements (CTRL), or the SUP diet, formulated as the CTRL with an increase in tryptophan (TRP) content. After 2 and 13 weeks of feeding, head-kidney (HK), liver (L) and white skeletal muscle (WSM) were collected for gene expression, whereas plasma was suited for humoral immune parameters. A holistic approach using transcriptomic, humoral and zootechnical parameters was undertaken. The expression of 29-31 genes for WSM, L or HK confirms an effect due to the treatment across time. A two-way ANOVA analysis revealed that 15-24 genes varied significantly depending on the tissue, and the multivariate analysis by means of PLS-DA explained (R-2) and predicted (Q(2)) with four components up to 93% and 78% of total variance, respectively. Component 1 (R-2 = 50.06%) represented the time effects, whereas components 2 (24.36%) and 3 (13.89%) grouped fish on the basis of dietary treatment, at early sampling. The HK results in particular suggest that fish fed SUP diet displayed an immunostimulated state at 2 weeks. No major differences were observed in plasma humoral parameters, despite an increase in antiprotease and peroxidase activities after 13 weeks regardless of dietary treatment. These results suggest that tryptophan supplementation may improve the seabream immune status after 2 weeks. Hence, the use of functional feeds is especially relevant during a short-term feeding period before a predictable stressful event or disease outbreak, considering that these putative advantageous effects seem to disappear after a 13 weeks feeding period.
- Does a ghrelin stimulus during zebrafish embryonic stage modulate its performance on the long-term?Publication . Navarro-Guillén, Carmen; Dias, Jorge; Rocha, Filipa; Castanheira, M. F.; Martins, Catarina I. M.; Laizé, Vincent; Gavaia, Paulo; Engrola, SofiaMetabolic programming refers to the induction, deletion, or impaired development of a somatic structure or "setting" of a physiological system by an early life stimulus operated at a critical period during development. Ghrelin is the only known orexigenic gut hormone, is an acylated peptide that acts as an endogenous ligand specific for growth-hormone secretagogue-receptor. The aim of the present work was to evaluate if an in ovo ghrelin administration could positively influence the zebrafish performance in the long-term and to gain insight on the mechanisms associated to ghrelin regulation of food intake during the larval phase. Food intake, growth potential, protein metabolism, expression of target genes involved in ghrelin, feeding behaviour regulation and locomotor activity were assessed in zebrafish (Danio rerio) larvae at 25 days post-fertilization. Elevated levels of acylated ghrelin in zebrafish eggs did not result in increased growth or food intake. Differences in mRNA expression between larvae fasted for 16 h before and 1 h after feeding were found for igf1ra, gh1 and pomca. Moreover, ghrelin treated larvae showed higher swimming activity, indicating that the peptide may have an important role on foraging activity. The present study addressed for the first time the effects of an early stimulus of ghrelin during the embryonic stage of zebrafish, however, further studies are needed to clarify the metabolic pathways affected by the early stimulus as well as focus on the effects on metabolic regulation of energy balance through lipid and carbohydrate metabolism.