Nutritional physiology during development of Senegalese sole (Solea senegalensis)
ABSTRACT The Senegalese sole, a species with a complex metamorphosis, difficulties in weaning and with occasional problems of malpigmentation and skeletal deformities, is a good model species to study larval nutritional physiology. In addition, the early metamorphosis and acquisition of a peculiar non-proactive bottom-feeding behaviour make early weaning an important issue in sole hatcheries. The present work reviews recent findings in different aspects of nutritional physiology during the development of Senegalese sole, in an attempt to optimize the composition of sole diets and to understand what are the limiting factors for weaning sole. Both digestive enzymes activity and tracer studies using 14C-Artemia show that sole larvae, even at young stages, have a high capacity for digesting live preys. This is reflected in a high growth potential and low mortality rates for this species during the larval stage compared to other marine fish species. Based on the observation of the digestive enzymes profile, early introduction of inert microdiets in co-feeding with Artemia does not seem to affect intestinal function. However, when co-feeding is not provided, intestinal activity may be depressed. Furthermore, early introduction of microdiets in co-feeding with Artemia may have a positive effect on survival rates, but at the expense of lower growth rates and higher size dispersal. This may reflect variation in the adaptation capacity of individual larvae to inert diets. High dietary neutral lipid (soybean oil) content results in reduced growth and accumulation of lipid droplets in the enterocytes and affects the capacity of Senegalese sole larvae to absorb and metabolise dietary fatty acids (FA) and amino acids (AA). Through tube feeding of different 14C-lipids and free FA it has been shown that FA absorption efficiency increases with unsaturation and that sole larvae spare DHA from catabolism. In addition, it was demonstrated that absorption efficiency varies according to molecular form, being highest for free FA, lowest for triacylglycerols and intermediate for phospholipids. Live preys commonly used in larviculture do not seem to have a balanced AA profile for sole larvae. Furthermore, the ideal dietary AA composition probably changes during development. Rotifers and Artemia metanauplii are apparently deficient in one or more of the following AA depending on the larval development stage: histidine, sulphur AA, lysine, aromatic AA, threonine and arginine. It has also been demonstrated that balancing the dietary AA profile with dipeptides in Artemia-fed larvae increases AA retention and reduces AA catabolism. When supplementing larval diets with limiting AA it should also be considered that sole larvae have different absorption, and retention efficiencies for individual AA, and that they have the capacity to spare indispensable AA. In addition, the absorption of free AA is faster and more efficient than that of complex proteins. Improvements in biochemical composition of inert microdiets for sole are likely to contribute to the reproducible weaning success of Senegalese sole.
Full-textDOI: · Available from: Laura Ribeiro, Jul 30, 2015
- SourceAvailable from: Eduardo Jiménez-Fernández
[Show abstract] [Hide abstract]
- "The Senegalese sole (Solea senegalensis) is a high interest aquaculture flatfish species with a high economical relevance in Southern European aquaculture (Imsland et al., 2003). Significant advances on larval rearing and weaning strategies have been achieved over the last years (Cañavate and Fernandez-Diaz, 1999; Conceição et al., 2007; Engrola et al., 2007; Fernandez-Diaz et al., 2001). However, knowledge about the role of vitamins in sole larvae is still scarce. "
ABSTRACT: The aim of this work was to assess the effects of a dietary supplement of vitamin C (as ascorbyl palmitate, AP) delivered through new and optimized alginate microcapsules (MA) on larval performance, antioxidant status and gene expression profiles. For this purpose, three MA (referred to as MA-1, MA-2 and MA-3) with increasing AP content ranging from 1,700 to 5,700 µg AP g−1 DW were assayed. Sole larvae were fed the three MA from first feeding to 7 days post-hatch (dph) and later replaced by Artemia from 7 to 28 dph. The experimental groups were performed in triplicate using a recirculation system. The efficiency of AP inclusion into MA was 55 %. At 7 dph, larval ascorbic acid (AA) content was proportional to the AP concentration included in MA (p<0.05). Larval growth until 7 dph was low but significantly higher in larvae fed MA-2 and MA-3. After Artemia supplying, a compensatory growth was detected in the three experimental groups whereas a faster metamorphic process and a higher weight at 28 dph in larvae fed MA with a higher AP content (MA-2 and MA-3) was observed (p<0.05). Moreover, Artemia feeding substantially increased the larval AA content during development peaking at 18 dph and decreasing at the end of metamorphosis with significantly lower AA levels in larvae fed MA-3. This reduction coincided with a higher total antioxidant capacity and lipid peroxidation whereas no differences in catalase or total glutathione peroxidase were detected. Expression data revealed that MA diets significantly modified the transcript levels of 16 genes involved in antioxidant defence (gpx1), tissue structure (col1a1 col1a2 and col1a3), stress (hsc70-1, hsc70-2, hsc70-3, gr1, gr2, pomcb), glycolytic pathway (gapdh1 and pkm), osmoregulation (cftr, nkcc2 and nkcc1) and pigmentation (mc1r). All these data reveal novel new insights about role of vitamin C during early stages of S. senegalensis to modulate growth, stress and antioxidative status in later developmental stagesAquaculture 06/2015; 443:65-76. DOI:10.1016/j.aquaculture.2015.03.013 · 1.83 Impact Factor
[Show abstract] [Hide abstract]
- "Senegalese sole larvae presents high capacity to digest live prey from the onset of exogenous feeding, this being reflected in high growth rates (Conceição et al., 2007). The enzymatic and histological development of the digestive system in Senegalese sole larvae based on just one daily sample has been previously studied (Conceição et al., 2007; Martínez et al., 1999; Padrós et al., 2011; Ribeiro et al., 1999a, 1999b), concluding that they exhibit digestive enzyme activity before mouth opening and a fast development of the digestive system between hatching and first feeding. Although the existence of daily feeding rhythms with an active nocturnal behavior has been reported in juveniles and adults of this species (Bayarri et al., 2004; Cañavate et al., 2006; Navarro et al., 2009), it is not clear when and how the feeding behavior turns diurnal to nocturnal habits. "
ABSTRACT: The aim of this study was to examine patterns of food intake and production of the main digestive enzymes of Senegalese sole larvae under a fixed 12 h light:12 h dark cycle. Daily gut content, soluble protein content and digestive enzyme activities were studied at different times of day in pelagic sole larvae (onset of feeding and 6 days post-hatch; dph) and in benthonic sole post-larvae (20 and 30 dph). The larvae displayed temporal changes in food intake throughout development. Pre-metamorphic larvae ceased feeding after lights were turned off. In contrast, post-metamorphic larvae continued to feed during the day, with a higher food intake occurring during dark phase. It was demonstrated that larval digestive enzymes, mainly lipases, were active before mouth opening. Tryptic activity varied with food intake at pre-metamorphic larvae, whereas its activity levels were kept along the day in post-metamorphic larvae.Aquaculture 01/2015; 435:33–42. DOI:10.1016/j.aquaculture.2014.09.017 · 1.83 Impact Factor
[Show abstract] [Hide abstract]
- "Moreover , shifts in the enriched live prey given to the larvae induced alterations of their fatty acid profile concomitant with the new prey administered (ARA-H −/+ and ARA-H +/− diets) demonstrating the rapid response of the larvae to the alterations in the dietary fatty acid profile (Lund et al., 2008). This rapid change in fatty acids was most likely related to the relatively fast growth during early stages of development (Conceição et al., 2007). Larval survival rates were high similarly to what has been obtained in previous studies on this species (Boglino et al., 2012a,b; Morais et al., 2005a,b). "
ABSTRACT: High dietary levels of arachidonic acid (ARA) and its relative proportions with eicosapentaenoic acid (EPA), fed during early larval stages, have been associated with malpigmentation in various flatfish species. This study investigated whether the nutritional induction of pigmentary disorders at larval stages was related to a specific larval period of increased sensitivity to ARA in Senegalese sole (Solea senegalensis Kaup, 1858). Senegalese sole larvae were fed high dietary ARA levels during pre- and pro-metamorphosis (2–15 dph) and/or post-metamorphosis (15–50 dph). Larval tissues reflected the dietary fatty acid composition. Malpigmentations were significantly related to elevated dietary and larval ARA contents and ARA/EPA ratio. This study reports evidence for a “pigmentation window”, with a higher larval sensitivity to dietary ARA during pre- and pro-metamorphosis than post-metamorphosis. High dietary ARA fed to larvae during pre-metamorphosis enhanced survival, but did not affect growth nor eye migration. The aspect and density of melanophores in the skin of the ocular side of ARA-induced pseudo-albinos were significantly reduced in comparison to normally pigmented individuals, even more in the pseudo-albino fish fed high dietary ARA levels during the pre-metamorphic stage. Pseudo-albino fish fed high dietary ARA levels during post-metamorphosis showed higher concentrations of 2- and 3-series prostaglandins (PGE2 and PGE3) than normally pigmented specimens fed the same diets. An increased sensitivity to ARA-induced malpigmentations has been identified at pre-metamorphosis and early metamorphosis in Senegalese sole. Supplying high dietary ARA amounts imbalanced the dietary ARA/EPA ratio and disrupted the relative concentrations of derived PGE2 and PGE3, resulting in 20 to 81.7% pseudo-albino individuals, depending on the dietary treatment. The administration of high levels of dietary ARA at different developmental stages did not only affect the incidence of animals with pigmentary disorders, but it also affect the melanophore density and skin aspect in normally pigmented and pseudoalbino fish as image segmentation and texture analyses indicated.Aquaculture 09/2014; 433:276–287. DOI:10.1016/j.aquaculture.2014.06.012 · 1.83 Impact Factor