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- Recent advances in nutrition of fish larval | Avanços recentes em nutrição de larvas de peixesPublication . Conceição, L. E. C.; Aragão, C.; Richard, Nadège; Engrola, S.; Gavaia, Paulo J.; Mira, Sara; Dias, J.Os requisitos nutricionais de larvas de peixes são ainda mal compreendidos, o que leva a altas mortalidades e problemas de qualidade no seu cultivo. Este trabalho pretende fazer uma revisão de novas metodologias de investigação, tais como estudos com marcadores, genómica populacional, programação nutricional, génomica e proteómica funcionais, e fornecer ainda alguns exemplos das utilizações presentes e perspectivas futuras em estudos de nutrição de larvas de peixes.
- Skeletal evaluation and technical improvements to decrease the incidence of skeletal deformities in Solea senegalensis, KaupPublication . Gavaia, Paulo J.; Richard, Nadège; Dâmaso, L.; Dinis, Maria Teresa; Pousão-Ferreira, P.; Engrola, S.; Conceição, L. E. C.; Cancela, LeonorThe appearance of skeletal deformities is a major problem associated to intensive, large-scale culture of fish species, affecting growth, development and ultimately, survival of produced fish. Although the mechanisms working behind it are still unclear, it is known that environmental, genetic and nutritional factors play fundamental roles. Given its importance as a vertebrate model to study skeleton-related diseases, the selection of an appropriate dietary protocol is a critical step in order to diminish the nutritional effect on bone and cartilage development. To better understand the effect of diet on skeletal development and deformities, as well as on larvae and juvenile global performance, we have tested four distinct dietary regimes, composed of rotifers Brachionus sp., Artemia nauplii and dry, formulated food.
- Comparing skeletal development of wild and hatchery-reared Senegalese sole (Solea senegalensis, Kaup 1858): Evaluation in larval and postlarval stagesPublication . Gavaia, Paulo J.; Domingues, S.; Engrola, S.; Drake, P.; Sarasquete, C.; Dinis, Maria Teresa; Cancela, LeonorThe Senegalese sole is a marine pleuronectiform that naturally occurs in Southern Europe and Mediterranean region where it is being produced in aquaculture, in particular in Portugal and Spain. The aim of this study was to assess the quality of hatchery-reared larvae in comparison with those reared in the wild, and determine to which extension wild growing larvae are also affected by skeletal deformities. The main structures affected included those forming the axial skeleton, the caudal fin complex and both anal and dorsal fins, with the most prevalent anomalies affecting caudal vertebrae and arches. Hatchery-reared fish presented a higher incidence of deformities (79%) compared with the 19% observed in wild specimens. In wild postlarvae collected in Autumn no deformities were observed. This work clearly shows that wild Senegalese sole present less skeletal deformities than those hatchery-reared during larval stages, indicating a selective mortality of wild deformed fish and/or an effect of aquaculture-related rearing conditions in the development of skeletal deformities in sole.
- Effect of pre-weaning feeding regime on weaning performance of Senegalese sole, Solea senegalensis (Kaup, 1858)Publication . Engrola, S.; Conceição, L. E. C.; Gavaia, Paulo J.; Cancela, Leonor; Dinis, Maria TeresaDespite much interest in the production of Senegalese sole (Solea senegalensis) in southern Europe, weaning of this species onto artificial diets is problematic and varying results are obtained. The aim of this study was to test two feeding frequencies during a 13-day pre-weaning period and assess their impact on the growth and survival of Senegalese sole. Postlarvae were fed Artemia metanauplii with a peristaltic pump every hour for 12 hours per day or twice daily (morning and late afternoon). Both groups were suddenly weaned onto a commercial diet for an additional 30 days. At the end of the experiment, the relative growth rate and final dry weight were significantly higher and the survival significantly lower in the 12-hour treatment than in the twice-daily treatment. The feeding frequency had no effect on condition factor. The incidence of deformities was about 80% in both treatments.
- Effects of pre-weaning feeding regime on weaning performance of Senegalese sole, Solea senegalensis (Kaup, 1858)Publication . Engrola, S.; Conceição, L. E. C.; Gavaia, Paulo J.; Cancela, Leonor; Dinis, Maria TeresaDespite much interest in the production of Senegalese sole (Solea senegalensis) in southern Europe, weaning of this species onto artificial diets is problematic and varying results are obtained. The aim of this study was to test two feeding frequencies during a 13-day pre-weaning period and assess their impact on the growth and survival of Senegalese sole. Postlarvae were fed Artemia metanauplii with a peristaltic pump every hour for 12 hours per day or twice daily (morning and late afternoon). Both groups were suddenly weaned onto a commercial diet for an additional 30 days. At the end of the experiment, the relative growth rate and final dry weight were significantly higher and the survival significantly lower in the 12-hour treatment than in the twice-daily treatment. The feeding frequency had no effect on condition factor. The incidence of deformities was about 80% in both treatments.
- 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.