Browsing by Author "Figueira, L."
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- 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.
- 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.
- How does fish metamorphosis affect aromatic amino acid metabolism?Publication . Pinto, W.; Figueira, L.; Dinis, Maria Teresa; Aragão, C.Aromatic amino acids (AAs, phenylalanine and tyrosine) may be specifically required during fish metamorphosis, since they are the precursors of thyroid hormones which regulate this process. This project attempted to evaluate aromatic AA metabolism during the ontogenesis of fish species with a marked (Senegalese sole; Solea senegalensis) and a less accentuated metamorphosis (gilthead seabream; Sparus aurata). Fish were tube-fed with three l-[U-14C] AA solutions at pre-metamorphic, metamorphic and post-metamorphic stages of development: controlled AA mixture (Mix), phenylalanine (Phe) and tyrosine (Tyr). Results showed a preferential aromatic AA retention during the metamorphosis of Senegalese sole, rather than in gilthead seabream. Senegalese sole’s highly accentuated metamorphosis seems to increase aromatic AA physiological requirements, possibly for thyroid hormone production. Thus, Senegalese sole seems to be especially susceptible to dietary aromatic AA deficiencies during the metamorphosis period, and these findings may be important for physiologists, fish nutritionists and the flatfish aquaculture industry.
- Is dietary taurine supplementation beneficial for gilthead seabream (Sparus aurata) larvae?Publication . Pinto, W.; Figueira, L.; Santos, A.; Barr, Y.; Helland, S.; Dinis, Maria Teresa; Aragão, C.This study evaluated the effect of dietary taurine supplementation on the growth performance and methionine metabolism of gilthead seabream larvae. For this purpose, a growth experiment was carried out in which seabream larvae were fed upon rotifers supplemented with “blank” or taurine-enriched liposomes. A complementary trial was also done in which seabream larvae fed with live prey were subsequently tube-fed a solution containing a L-[U-14C] methionine with or without a taurine supplement. Results from the growth experiment showed that rotifers were successfully enriched with taurine, but no effects were observed on larval growth performance, survival or amino acid composition. Furthermore, dietary taurine supplementation did not result in an increase of larval taurine levels, a factor that may have been determinant for the absence of effects observed on growth performance. In the tube-feeding trial, results showed that dietary taurine supplementation led to an increase of methionine retention in larvae. These findings suggest the existence of an active taurine biosynthesis pathway for gilthead seabream during the larval stage. Hence, gilthead seabream may not be dependent on dietary taurine to maintain the taurine body pool, since it may convert taurine from methionine if required. Taken together, the results from this study indicate that dietary taurine supplementation does not seem to enhance the larval growth performance in fish species able to biosynthesise taurine during this stage, which seems to be the case of gilthead seabream. However, this study also showed that in these species, dietary taurine supplementation may ultimately affect larval metabolism by increasing methionine availability for several important physiological purposes, contributing to a better understanding on the role of taurine during the early life stages of fish development.