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- Improving weaning strategies for Senegalese sole: effects of body weight and digestive capacityPublication . Engrola, S.; Conceição, L. E. C.; Dias, L.; Pereira, R.; Ribeiro, Laura; Dinis, Maria TeresaTo optimize Senegalese sole-weaning strategies, three experiments were performed.The first trial tested four weaning strategies with a10mg sole. Artemia-fed sole grew threefold less than fish fed an inert diet. Sudden weaning (abrupt change from Artemia to inert diet) and weaning with co-feeding produced larger sole than did a late weaning treatment; delayed weaning negatively affected ¢sh growth. In the second experiment, the digestive capacity of early-weaned 1, 2 and 4mg sole was investigated. The highest growth was observed in sole weaned at 4mg. Digestive enzyme pro¢les suggest that sole have an adaptation period to inert diets, with reduced feed intake. This adaptation period is inversely proportional to post-larvae weight. The third experiment examined weaning with cofeeding at di¡erent weights (2,5 and11mg).These studies demonstrate that sole of 5^10mg can be weaned, with high survival rates. On the basis of the digestive enzyme pro¢les, the early introductionof inert diets in co-feeding with Artemia seems to affect intestinal processes in smaller postlarvae. This study also suggests that trypsin and alkaline phosphatase may be used as indicators of nutritional status in sole ofo5mg.
- Facultative secondary lecithotrophy in the megalopa of the shrimp Lysmata seticaudata (Risso, 1816) (Decapoda : Hippolytidae) under laboratory conditionsPublication . Calado, Ricardo; Dionisio, Gisela; Nunes, Cristovao; Dinis, Maria TeresaCertain decapod crustaceans can catabolize internal reserves to undergo partial or full larval development. This feature is termed secondary lecithotrophy, if energy used results from plankton derived organic matter accumulated Ig earlier larval stages. The present work reports the ability of Lysmata seticaudata megalopa to moll to the first juvenile stage in the absence of food. Unlike previous records of secondary lecithotrophy displayed by nonfeeding last larval stages of hermit crabs and spiny lobsters, the megalopa of L. seticaudata retains its feeding capacity. This is the first time such a feature has been reported in decapods, and the term facultative secondary lecithotrophy is proposed. The build up of energy reserves continues during the last zoeal stage of L. seticaudata, with starved zoea IX failing to molt to megalopa. Energy reserves that enable starved megalopa to molt to juvenile seem to be partially depleted, with starved juveniles produced either from, starved or fed megalopae being unable to molt to the next juvenile stage. The longer resistance of starved juveniles produced from fed megalopae (nine days), compared to that of starved juveniles produced from starved megalopae (five days), indicates that some energy reserves may pass to juvenile, not being totally depleted at metamorphosis.
- Growth, stress response and free amino acid levels in Senegalese sole (Solea senegalensis Kaup 1858) chronically exposed to exogenous ammoniaPublication . Pinto, W.; Aragão, C.; Soares, Florbela; Dinis, Maria Teresa; Conceição, L. E. C.Stressful husbandry conditions are likely to a¡ect growth and amino acid metabolism in ¢sh. In this study, chronic ammonia exposure was used to test the e¡ects of a stressor on growth and amino acid metabolism of Senegalese sole juveniles. The ¢sh were exposed for 52 days to 11.6 mg L 1 [low-TAN (L-TAN)] or 23.2 mg L 1 [high-TAN (H-TAN)] of total ammonia nitrogen (TAN), or to 0 mg L 1 (Control). Growth in L-TAN groups was slightly but signi¢- cantly di¡erent from the Control groups [relative growth rate (RGR50.35 0.13 and 0.52 0.23% day 1respectively)]. In H-TAN groups, growth was severely a¡ected (RGR50.01 0.13% day 1 ).
- Dietary taurine supplementation enhances metamorphosis and growth potential of Solea senegalensis larvaePublication . Pinto, W.; Figueira, L.; Ribeiro, L.; Yúfera, M.; Dinis, Maria Teresa; Aragão, C.The effect of dietary taurine supplementation on growth performance, metamorphosis success and amino acid metabolism of Senegalese sole (Solea senegalensis) larvae was investigated. These parameters were assessed in larvae fed control and taurine supplemented microcapsules during the pelagic phase. Subsequently, a similar evaluation was carried out in newly settled larvae fed upon Artemia, in order to verify the effect of earlier dietary taurine supplementation in larvae reared under improved feeding conditions. Results showed that dietary taurine supplementation did not affect larval growth performance and metamorphosis during the pelagic phase. However, by the end of the trial, Senegalese sole previously fed taurine supplemented microcapsules had a significantly higher growth performance and metamorphosis completion success than larvae fed control microcapsules. These differences were likely related to the improvement of feeding conditions upon settlement, which probably helped revealing the positive effects of earlier dietary taurine supplementation on Senegalese sole performance. Additionally, Senegalese sole may have benefited from taurine antioxidant properties during metamorphosis, since larval antioxidant defences may saturate at this stage. Furthermore, results from metabolic trials have shown that dietary taurine supplementation significantly increased amino acid retention in Senegalese sole larvae when a concomitant increase of taurine body levels was found. Therefore, an increase in larval growth potential and metamorphosis success was observed under dietary taurine supplementation and these results may help understanding why dietary taurine supplementation has been reported to simultaneously increase taurine body levels and growth performance in other fish species, leading to a better comprehension on the role of taurine during fish development.
- Weaning of Senegalese sole (Solea senegalensis) postlarvae to an inert diet with a co-feeding regime | Destete de postlarvas del lenguado senegalés (Solea senegalensis) a una dieta inerte utilizando un régimen de coalimentaciónPublication . Ribeiro, Laura; Engrola, S.; Dinis, Maria TeresaThe objective of this study was to evaluate the weaning success of Senegalese sole, Solea senegalensis, postlarvae when cofed a compound diet, by means of the analysis of growth parameters (relative growth rate [RGR] and condition factor [K]), survival, protein and lipid content. Total ammonia in the rearing water was also measured. The experiment lasted for 46 days (36 to 82 days posthatching). One group was fed only with enriched Artemia sp. metanauplii (Artemia treatment), whereas in another group, the Artemia sp. metanauplii were gradually replaced by the International Council for the Exploration of the Sea (ICES) diet over a period of 39 days (ICES treatment). Postlarvae were sampled on rearing days 0, 9, 23, 30, 39 and 46 for growth and biochemical analysis. Water was sampled on rearing day 30 during a 24-h cycle in both treatments. Postlarvae from the ICES treatment were weaned, though by the end of the experiment the Artemia treatment exhibited significantly higher values for growth, RGR, K and survival rates (P <0.05). No significant differences were observed concerning total lipid content. Protein content was significantly higher for the Artemia treatment after 46 days of rearing (P < 0.05). The total ammonia nitrogen concentration in the water increased after each meal and remained below a harmless level for postlarvae.
- Natural fortification fortification of trout with dietary macroalgae and selenised-yeast increases the nutritional contribution in iodine and seleniumPublication . Ribeiro, Ana Ramalho; Gonçalves, Amparo; Bandarra, Narcisa; Nunes, Maria Leonor; Dinis, Maria Teresa; Dias, Jorge; Rema, PauloFish and seafood consumption are increasing worldwide and the contribution of aquaculture products to consumers' diets is significant. External feeding in aquaculture unlocks the possibility of tailoring fish products with health beneficial compounds. A study was undertaken to evaluate the feed fortification with an iodine rich macroalgae (Laminaria digitata) and selenised yeast, at its maximum permitted levels, on minerals and vitamins content in rainbow trout edible part. Dietary supplementation resulted in a six-fold increase for iodine and a 2.9-fold increase for selenium contents in trout fillets without altering sensorial traits. The fortified fish presented a nutritional contribution of 12.5% DRI for iodine and 78% DRI for selenium, but all produced fish could supply 80% DRI for vitamin D3. Overall, fish from this trial could be labelled as "high in selenium and high in vitamin D3" under the EFSA definition for a functional food. (C) 2016 Elsevier Ltd. All rights reserved.
- Co-feeding in Senegalese sole larvae with inert diet from mouth opening promotes growth at weaningPublication . Engrola, S.; Figueira, L.; Conceição, L. E. C.; Gavaia, Paulo J.; Ribeiro, Laura; Dinis, Maria TeresaThe aim of this study was to determine if sole larvae co-fed with inert diet at mouth opening would perform better than larvae fed with live prey and if such a feeding regime would produce better quality juveniles. The experiment was separated in to two phases: pelagic and benthic. In the pelagic phase, treatments consisted of the standard feeding regime (rotifer and Artemia feeding), the standard feeding regime and inert diet, and rotifer for a longer period than the standard feeding regime until larvae reached 9 days after hatching (DAH). By the end of the pelagic phase, when the postlarvae were 20 DAH, sole that were co-fed with inert diet from mouth opening, were significantly smaller in weight than postlarvae fed exclusively with live prey. Sole digestive maturation was improved by co-feeding the inert diet. Survival rates, skeletal deformities and quality evaluation were not affected by the feeding regimes. In the benthic phase, the postlarvae from standard feeding regime (pelagic phase) were separated in to two treatments: standard live Artemia metanauplii until weaning and standard frozen Artemia metanauplii until weaning. Remaining treatments were the follow up of treatments from the pelagic phase. At the end of the experiment i.e. 68 DAH, the postlarvae co-fed with inert diet from mouth opening were significantly larger than all the postlarvae from remaining feeding regimes. The results of the present study demonstrate that it is possible to offer inert diet to sole at mouth opening in a co-feeding regime and to produce better quality postlarvae. Co-fed sole were larger and had a better tail condition at the end of the weaning.
- Weaning of Senegalese sole (Solea senegalensis) postlarvae to an inert diet with a co-feeding regimePublication . Ribeiro, Laura; Engrola, S.; Dinis, MTThe objective of this study was to evaluate the weaning success of Senegalese sole, Solea senegalensis, postlarvae when co-fed a compound diet, by means of the analysis of growth parameters (relative growth rate [RGR] and condition factor [K]), survival, protein and lipid content. Total ammonia in the rearing water was also measured. The experiment lasted for 46 days (36 to 82 days posthatching). One group was fed only with enriched Artemia sp. metanauplii (Artemia treatment), whereas in another group, the Artemia sp. metanauplii were gradually replaced by the International Council for the Exploration of the Sea (ICES) diet over a period of 39 days (ICES treatment). Postlarvae were sampled on rearing days 0, 9, 23, 30, 39 and 46 for growth and biochemical analysis. Water was sampled on rearing day 30 during a 24-h cycle in both treatments. Postlarvae from the ICES treatment were weaned, though by the end of the experiment the Artemia treatment exhibited significantly higher values for growth, RGR, K and survival rates (P < 0.05). No significant differences were observed concerning total lipid content. Protein content was significantly higher for the Artemia treatment after 46 days of rearing (P < 0.05). The total ammonia nitrogen concentration in the water increased after each meal and remained below a harmless level for postlarvae.