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- Replacement of Antarctic krill (Euphausia superba) by extruded feeds with different proximate compositions: effects on growth, nutritional condition and digestive capacity of juvenile European lobsters (Homarus gammarus, L.)Publication . Goncalves, Renata; Gesto, Manuel; Teodosio, Maria; Baptista, Vânia; Navarro-Guillén, Carmen; Lund, IvarExtruded feeds are widely used for major aquatic animal production, particularly for finfish. However, the transition from fresh/frozen to extruded/pelleted feeds remains a major obstacle to progressing sustainable farming of European lobster ( Homarus gammarus). The aim of the present study was to investigate the effects of using extruded feeds with different protein levels and lipid/carbohydrate ratios on growth, feed utilisation, nucleic acid derived indices (sRD) and digestive enzymatic activity of H. gammarus juveniles. Six extruded feeds were formulated to contain two protein levels (400 and 500 g/kg), with three lipid/carbohydrate ratios (LOW - 1:3; MEDium - 1:2; HIGH - 1:1). The extruded feeds were tested against Antarctic krill (Euphausia superba) used as control (CTRL). Overall, the CTRL and 500MED feed supported the highest growth and nutritional condition estimated by means of sRD, while the poorest results were observed for the 400HIGH and 400MED groups. The FCR was significantly lower in the CTRL than all extruded feeds, among which the most efficient, i.e., lower FCR, was the 500MED. The highest activity of trypsin and amylase in lobsters fed the 400MED and 400HIGH feeds points to the activation of a mechanism to maximise nutrients assimilation. The highest lipase activity observed for the 500LOW and 500MED groups indicates a higher capacity to metabolise and store lipids. Overall, the results suggest that the 500MED feed (500 g/kg protein, 237 g/kg carbohydrates and 119 g/kg lipids) is a suitable extruded feed candidate to replace Antarctic krill, commonly used to grow lobster juveniles.
- Effect of varying dietary levels of LC-PUFA and vegetable oil sources on performance and fatty acids of Senegalese sole post larvae: Puzzling results suggest complete biosynthesis pathway from C18 PUFA to DHAPublication . Navarro-Guillén, Carmen; Engrola, S.; Castanheira, Maria Filipa; Bandarra, N.; Hachero-Cruzado, Ismael; Tocher, Douglas R.; Conceição, L. E. C.; Morais, S.Lipid nutrition of marine fish larvae has focused on supplying essential fatty acids (EFA) at high levels to meet requirements for survival, growth and development. However, some deleterious effects have been reported suggesting that excessive supply of EFA might result in insufficient supply of energy substrates, particularly in species with lower EFA requirements such as Senegalese sole (Solea senegalensis). This study addressed how the balance between EFA and non-EFA (better energy sources) affects larval performance, body composition and metabolism and retention of DHA, by formulating enrichment emulsions containing two different vegetable oil sources (olive oil or soybean oil) and three DHA levels. DHA positively affected growth and survival, independent of oil source, confirming that for sole post-larvae it is advantageous to base enrichments on vegetable oils supplying higher levels of energy, and supplement these with a DHA-rich oil. In addition, body DHA levels were generally comparable considering the large differences in their dietary supply, suggesting that the previously reported ∆4 fatty acyl desaturase (fad) operates in vivo and that DHA was synthesized at physiologically significant rates through a mechanism involving transcriptional up-regulation of ∆4fad, which was significantly up-regulated in the low DHA treatments. Furthermore, data suggested that DHA biosynthesis may be regulated by an interaction between dietary n − 3 and n − 6 PUFA, as well as by levels of LC-PUFA, and this may, under certain nutritional conditions, lead to DHA production from C18 precursors. The molecular basis of putative fatty acyl ∆5 and ∆6 desaturation activities remains to be fully determined as thorough searches have found only a single (∆4) Fads2-type transcript. Therefore, further studies are required but this might represent a unique activity described within vertebrate fads.
- Fast growing greater amberjack post-larvae require a high energy-high protein weaning dietPublication . Navarro-Guillén, Carmen; Conceicao, L. E. C.; Pinto, W.; Siguero, I; Urrutia, P.; Moyano, F. J.; Yufera, M.Larvae and early juveniles of fast-growing fish species show tremendous growth potential, leading to higher requirements for protein, high-unsaturated fatty acids, and other nutrients. Several commercial weaning diets with relatively high success have been developed for low/moderate-growing species however, additional challenges are outlined to meet growth potential and energy requirements of such fast-growing species. The objective of the present study was to evaluate two commercial microdiets for marine fish, one having simultaneously a very high protein and high lipid contents (HIGH), and another (MOD) with a high protein and moderate lipid content, in a growth performance trial with greater amberjack post-larvae from 33 to 78 days after hatching. Moreover, histological preparations of liver, anterior and posterior intestine were assessed for hepatic and intestinal lipid inclusions quantification and gut epithelial brush height measurement. Activities of the digestive enzymes: pepsin, trypsin, chymotrypsin, lipase and amylase were also analyzed. Post-larvae fed HIGH microdiet exhibited higher final weight and lower feed conversion ratio that those fed on MOD microdiet. Liver displayed a higher level of lipid inclusions for the MOD diet than for HIGH diet. Moreover, enterocytes of posterior intestine presented a much higher level of supranuclear vacuoles for the HIGH diet compared to MOD diet. The lower Trypsin/Chymotrypsin ratio observed at the end of the experiment in larvae fed on MOD diet may indicate a deficiency in protein of this diet. Together, these results support that larvae of greater amberjack, and likely other fast-growing marine fish species, require high protein-high lipid microdiets. The use of microdiets developed targeting slower growing marine species may lead to sub-optimal performances in fast-growing larvae.
- Effect of increased rearing temperature on digestive function in cobia early juvenilePublication . Yúfera, M.; Nguyen, M.V.; Navarro-Guillén, Carmen; Moyano, F.J.; Jordal, A.-E.O.; Espe, M.; Conceição, L.E.C.; Engrola, Sofia; Le, M.H.; Rønnestad, I.The present study is focused to elucidate the main characteristics of the digestive function of this carnivorous fast-growing fish living at high temperatures. With this aim, we have examined the effects of an increased temperature from 30 to 34 °C on the daily pattern of gastrointestinal pH, enzymatic proteolytic digestive activity and the feed transit time in early juveniles of cobia (Rachycentron canadum), a species living in tropical and subtropical waters with an increasing aquaculture production. Fish were fed two meals a day. Gastric luminal pH was permanently acidic (mean pH values: 2.76-4.74) while the intestinal pH increased from neutral/slightly acidic to slightly alkaline when the digesta was present, with an increasing alkalinity from proximal to distal intestine (mean pH values: 6.05 to 7.69). The temperature did not affect the gastric pH but a slightly higher acidity was induced in the intestine at 34 °C. Pepsin activity showed a daily rhythm at 30 °C with maximum in the middle of the light period, while at 34 °C some hourly changes coinciding with feed adding without a clear daily trend during the 24-h period were observed. The trypsin activity exhibited a daily rhythm at both temperatures with an increase after morning feeding to reach a maximum several hours later. Average pepsin activity during the daily cycle was slightly higher at 34 °C (6.1 and 7.3 U mg-1 BW at 30 and 34 °C respectively), but values were significantly different only at 8 and 24 h after the morning meal. Similarly, the trypsin activity was significantly affected by the temperature only at 8 and 16 h after the morning meal, but daily activity averages were similar (1.20 and 1.29 U g-1 BW at 30 and 34 °C respectively). The partial transit rates of the first meal in the stomach for each period inter-samplings were higher during the first 4-h period and decreased progressively along the rest of the 24-h cycle at both temperatures, but no significant differences were detected at 30 °C. In addition, the transit was notably faster at 34 °C particularly during the first 8 h after feeding, with rates between 100 and 65% of total volume displaced (intake or released) during each 4-h period. In the intestine the transit rate was relatively constant and similar at both temperatures during 12 h after feeding. Then the rates remained very low during the following 12 h. Residence time of the first meal was longer at 30 than at 34 °C, particularly in the stomach (12 h:02 min vs 4 h:54 min respectively). In the intestine the difference was not so large (8 h:18 min vs 6 h:24 min respectively). In a parallel study under same conditions, cobia reared at 30 °C grew faster and showed a more favorable feed conversion ratio than those at elevated temperature (34 °C). The present results indicate that at 34 °C, a subtle increase of proteolytic activity cannot compensate for the faster gut transit rate. Therefore, 30 °C is more appropriate temperature for the early on-growing of cobia because at higher temperatures the digestion efficiency decrease being one of the causes for a lower growth.
- 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.
- Effects of dietary curcumin in growth performance, oxidative status and gut morphometry and function of gilthead seabream postlarvaePublication . Xavier, Maria João; Navarro-Guillén, Carmen; Lopes, André; Colen, R.; Teodósio, Rita; Mendes, Rodrigo; Oliveira, Beatriz; Valente, Luisa M.P.; Conceição, Luís E.C.; Engrola, SofiaAn imbalance in the production and detoxification of reactive oxygen species and other oxidants can disrupt a l l types of cellular compounds, and lead to a state of oxidative stress. Preventing this state is essential to improve growth and health in animal production. Therefore, the aim of this work was to assess i f the dieta r y supple-mentation of curcumin cou l d improve the antioxidant status and intestine structu r e and functionalit y of gilthead seabream postlarvae, with the global objective of improving fish growth performance and robustness. Two experimental diets supplemented with different doses of curcumin (LOW and HIGH diets), and a commercial diet were fed to quadruplicate groups of postlarvae, for 20 days. At the end of the feeding trial fish fed the supple-mented diets significantly improved their antioxidant status compared to CTRL fed fish. LOW and HIGH fed fish presented lower protein oxidative damage (P < 0.05) and higher total antioxidant capacity (P < 0.05). Moreover, postlarvae fed curcumin supplemented diets also presented an upregulation of nuclear factor erythroid 2 - related factor 2 (nrf2) and glutathione-disulfide reductase (gr) in HIGH (P < 0.05) and heat shock protein 70 (hsp70) in LOW treatments (P < 0.05). No differences were observed in growth performance, intestine morphome t r y , and digestive enzymes activities among treatments (P > 0.05). In conclusion, dieta r y curcumin supplementation was able to enhance gilthead seabream postlarvae robustness through a modulation of the oxidative status, increasing total antioxidant capacity and decreasing protein oxidative damage. This data pro-vide evidence that curcumin can be a suitable feed additive to promote heath status and robustness of fish at early stages of development, therefore contributing for the development and sustainabilit y of marine fish hatchery production.
- Dietary curcumin promotes gilthead seabream larvae digestive capacity and modulates oxidative statusPublication . Xavier, Maria João; Dardengo, Gian Marco; Navarro-Guillén, Carmen; Lopes, Andre D.; Colen, R.; Valente, Luisa M. P.; Conceição, Luís E. C.; Engrola, SofiaThe larval stage is highly prone to stress due to the ontogenetic and metabolic alterations occurring in fish. Curcumin inclusion in diets has been shown to improve growth by modulating oxidative status, immune response, and/or feed digestibility in several fish species. The aim of the present work was to assess if dietary curcumin could promote marine fish larvae digestive maturation and improve robustness. Gilthead seabream larvae were fed a diet supplemented with curcumin at dose of 0 (CTRL), 1.5 (LOW), or 3.0 g/Kg feed for 27 days. From 4 to 24 days after hatching (DAH), no differences were observed in growth performance. At the end of the experiment (31 DAH) LOW larvae had a better condition factor than CTRL fish. Moreover, HIGH larvae showed higher trypsin and chymotrypsin activity when compared to CTRL fish. LOW and HIGH larvae were able to maintain the mitochondrial reactive oxygen species production during development, in contrast to CTRL larvae. In conclusion, curcumin supplementation seems to promote larvae digestive capacity and modulate the oxidative status during ontogeny. Furthermore, the present results provide new insights on the impacts of dietary antioxidants on marine larvae development and a possible improvement of robustness in the short and long term.
- Ontogeny and diurnal patterns of molecular gene expression and activity of digestive enzymes in developing greater amberjackPublication . Gamberoni, P.; Yufera, M.; de las Heras, V; Siguero, I; Gilannejad, N.; Martinez-Rodriguez, G.; Navarro-Guillén, CarmenThe greater amberjack, Seriola dumerili, is a fast-growing pelagic teleost with great interest for the diversification of farmed marine fish species in the Mediterranean region. Aiming to advance the optimization of feeding during the early stage of this species, this study examines the ontogeny of digestive function using molecular and biochemical approaches. Gene expression of digestive enzyme precursors and the enzymatic activity have been determined during the first 51 days post hatching (dph) and during the diurnal period of 19 dph larvae reared in semi-intensive conditions. The expression of pancreatic proteases precursors (try3, ctra and ctrb1) increased from first-feeding, while gastric chitinase (chia1), gastric protease (pga3) and proton pump (atp4a2) after 10 dph. The expression of pancreatic lipases (cel1, cel2 and cel3) peaked between 6 and 10 dph, phospholipase A2 (pla2g1b) rose only after 25 dph, while a-amylase (amy2a) increased mainly from 20 dph. The trypsin activity was more evident from first-feeding to 25 dph and chymotrypsin activity from this day onwards. Acidic chitinase and pepsin activity appeared, respectively, at 16 and 30. The activity of 7C-like lipase was evident from first-feeding but as 4C-like lipase significantly increased from 15 dph, while amylase peaked from 6 to 22 dph. Aminopeptidase and alkaline phosphatase activities started at 20 dph indicating the functional maturation of brush border of the enterocytes. The daily pattern analysis showed a food anticipatory strategy in the expression of proteases related genes. Lipases activity was more evident during the morning hours, followed by amylase, and by alkaline proteases in the afternoon. Results, also, suggested an alternation in the activity of chymotrypsin and trypsin. These ontogenetic patterns are concordant with a carnivorous marine teleost.
- Ghrelin in Senegalese sole (Solea senegalensis) post-larvae: Paracrine effects on food intakePublication . Navarro-Guillén, Carmen; Yufera, Manuel; Engrola, SofiaSuccessful food consumption and digestion depend on specifics anatomical and behavioral characteristics and corresponding physiological functions that should be ready to work at the appropriate time. The physiological regulation of appetite and ingestion involves a complex integration of peripheral and central signals by the brain. Ghrelin is a peptide hormone involved in the control of energy homeostasis and increases food intake in mammals, however ghrelin has species-specific actions on food intake in fish. The aim of this study was to investigate whether this peptide has an orexigenic or anorexigenic role in Senegalese sole (Solea senegalensis) in order to improve the knowledge of the physiological basis underlying feeding activity. Feed intake was measured at several sampling points to determine the overall action time of the peptide and its effect in Senegalese sole food intake. Artemia protein digestibility and retention were determined in order to analyze the ghrelin effect in fed and fasted Senegalese sole post-larvae. Results suggested that ghrelin acts as orexigenic hormone in Senegalese sole, with a response time around 25 min. Results indicated that Senegalese sole post-larvae are able to maintain absorption and retention capacities independently of feeding rate and nutritional status. Furthermore, the present study gives insight for the first time of the fate of the retained amino acids, being mainly used for protein accretion (86.79% of retained amino acids recovered in protein and FAA fractions). (C) 2016 Elsevier Inc. All rights reserved.
- Effects of early-life amino acids supplementation on fish responses to a thermal challengePublication . Navarro-Guillén, Carmen; Jerez-Cepa, Ismael; D. Lopes, André; Mancera, Juan Miguel; Engrola, SofiaNutritional programming is a promising concept for promoting metabolic adaptation of fish to challenging conditions, such as the increase in water temperature. The present work evaluates in ovo arginine or glutamine supplementation as enhancers of zebrafish metabolic or absorptive capacity, respectively, at optimum (28 degrees C) and challenging temperatures (32 degrees C) in the long-term. Growth performance, free amino acids profile, methylation index and the activity levels of digestive and intermediary metabolism enzymes were analysed to assess the metabolic plasticity induced by an early nutritional intervention. Temperature affected fish larvae growth performance. At the end of the experimental period 28 degrees C-fish showed higher dry weight than 32 degrees C-fish. The effects of the early supplementation were reflected in the larval free amino acids profile at the end of the experiment. Higher methylation potential was observed in the ARG-fish. In ovo amino acid supplementation modulated the metabolic response in zebrafish larvae, however, the magnitude of this effect differed according to the amino acid and the temperature. Overall, arginine supplementation enhanced carbohydrates metabolism at 32 degrees C. In conclusion, the present work suggests that in ovo arginine supplementation may promote a better adaptive response to higher temperatures.