Browsing by Author "Valente, Luisa M. P."
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- 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.
- Dietary lipid level affects growth performance and nutrient utilisation of Senegalese sole (Solea senegalensis) juvenilesPublication . Borges, Pedro; Oliveira, Beatriz; Casal, Susana; Dias, Jorge; Conceicao, Luis; Valente, Luisa M. P.Over the last few years, several aspects of Senegalese sole (Solea senegalensis) culture have been developed and optimised but the dietary lipid level for optimal growth has never been determined. Hence, five isonitrogenous diets (56 % dietary protein) with increasing dietary lipid levels (4, 8, 12, 16 and 20 % DM) were fed to satiation to triplicate groups of twenty fish (mean initial weight 10 g). Fifteen tanks were randomly assigned one of the five diets. Feed was distributed using automatic feeders, and fish were fed over a 16-week period. At the end of the experiment the fish fed on diets containing the two lowest dietary lipid levels (4 and 8 %) showed a 3-fold body-weight increase with a significantly higher daily growth index than fish fed higher lipid levels (1-2 v. 0-8). Moreover, these fish displayed a significantly lower dry feed intake (12g/kg per d) and feed conversion ratio (1-0) compared with fish fed higher lipids levels (16-19 g/kg per d; feed conversion ratio 2-0). Low dietary lipid levels (< 12 %) significantly improved nutrient retention and gain and hence growth, without major effects on whole-body composition. Despite the slight alteration in n-3 PUFA muscle content in the fish fed low-fat-diets, this fish fed low dietary lipid still remains a rich n-3 PUFA product and generally maintained its nutritional value. These results evidenced a low lipid tolerance of Senegalese sole juveniles and suggest a maximal dietary inclusion level of 8 % lipids for both optimal growth and nutrient utilisation without compromising flesh quality.
- Dietary protein complexity modulates growth, protein utilisation and the expression of protein digestion-related genes in Senegalese sole larvaePublication . Canada, Paula; Conceicao, Luis E. C.; Mira, Sara; Teodósio, Rita; Fernandes, Jorge M. O.; Barrios, Carmen; Millan, Francisco; Pedroche, Justo; Valente, Luisa M. P.; Engrola, SofiaGiven its complex metamorphosis and digestive system ontogeny, Senegalese sole larvae capacity to digest and utilize dietary protein is likely to change throughout development. In the present study, we hypothesized that the manipulation of dietary protein complexity may affect Senegalese sole larvae capacity to digest, absorb and retain protein during metamorphosis, as well as the mRNA expression of genes encoding for the precursors of proteolytic enzymes of the digestive tract and the enterocyte peptide transporter PepT1, which may have further impact on somatic growth. Three diets were formulated using approximately the same practical ingredients, except for the main protein source. The Intact diet protein content was mostly based on intact plant protein where the target peptide molecular weight (MW) would be > 70 kDa. The PartH diet protein fraction was mostly based on a protein hydrolysate with a high content of 5-70 kDa peptides. The HighH diet protein fraction was mostly based on a protein hydrolysate with a high content of 5 kDa peptides. A growth trial was performed with larvae reared at 19 degrees C under a co-feeding regime from mouth opening. The transcription of pga, tryp1c, ialp, ampn and pepT1 (encoding respectively for PepsinogenA, Trypsinogen1C, Intestinal alkaline phosphatase, Aminopeptidase N and for the enterocyte peptide transporter 1) was quantified by qPCR, during the metamorphosis climax (16 DAH) and after the metamorphosis was completed (28 DAH). An in vivo method of controlled tube-feeding was used to assess the effect on the larvae capacity to utilize polypeptides with different MW (1.0 and 7.2 kDa) representing a typical peptide MW of each of the hydrolysates included in the diets. The PartH diet stimulated growth in metamorphosing larvae (16 DAH), whereas the Intact diet stimulated growth after 36 DAH. The Intact diet stimulated the larvae absorption capacity for 1.0 kDa peptides at 16 DAH, which may have contributed for enhanced growth in later stages. The PartH diet stimulated the transcription of tryp1c and pept1 at 28 DAH, which seemed to reflect on increased post-larvae capacity to retain dietary 7.2 kDa polypeptides. That may indicate a possible strategy to optimize the digestion and utilisation of the PartH dietary protein, though it did not reflect into increased growth. The Intact diet promoted the transcription of pepsinogenA, which may reflect a reduced gastrointestinal transit time, which could have enhanced the dietary nutrients assimilation, ultimately improving growth. The present results suggest that, whereas pre-metamorphic sole larvae utilize better dietary protein with a moderate degree of hydrolysis, post-metamorphic sole make a greater use of intact protein.
- Improving growth potential in Senegalese sole (Solea senegalensis) through dietary proteinPublication . Canada, Paula; Engrola, Sofia; Conceicao, Luis E. C.; Valente, Luisa M. P.In the present work, recent studies that contributed for improving dietary protein in practical microdiets for Senegalese sole larvae are revised, in an attempt to overcome some of the current problems in this species larviculture, such as the difficult early adaptation to inert diets and highly variable growth rates. Different diet formulation strategies were employed in an attempt to improve Senegalese sole larvae capacity to utilize and deposit protein throughout metamorphosis, to further maximize growth potential: (1) increasing indispensable amino acids (IAA) content (2) meeting the ideal IAA profile by adjusting the dietary AA profile to the larval body AA profile and (3) decreasing the complexity (molecular weight) of dietary protein to increase its digestibility. Either manipulating the quality or the complexity of dietary protein had impact on the larvae capacity to utilize protein and direct it for growth. Sole larvae seem to be able to adapt their digestive functions and metabolic capacity to dietary protein. Moreover, increasing the dietary IAA/DAA ratio and changing the degree of hydrolysis of dietary protein affected the expression pattern of muscle growth related genes, with consequences on muscle cellularity and potential for growth. The expression of DNA methyltransferases was altered in response to changes in dietary protein. The novelty of such information in fish may trigger further studies on the effect of dietary protein on the epigenetic regulation of growth. In conclusion, optimal protein quality for Senegalese sole seems to change during larval development. Whereas the inclusion of a moderately hydrolysed protein comes up as a promising way to improve growth in early larval stages, larger peptides and intact protein seem to be more suitable to sole post-larvae and young juveniles. Therefore, these results suggest that dietary protein fraction formulation of microdiets for Senegalese sole should be adapted to each developmental stage, what has important consequences for practical larval microdiets formulation and feeding protocols.
- Protein utilisation and intermediary metabolism of Senegalese sole (Solea senegalensis) as a function of protein:lipid ratioPublication . Borges, Pedro; Medale, Francoise; Dias, Jorge; Valente, Luisa M. P.Previous experiments with Senegalese sole (Solea senegalensis) have demonstrated that dietary lipid levels above 8% impaired growth and did not promote protein retention. We hypothesised that this low ability to use high-lipid diets may depend on the dietary protein level. In the present study, a 2 x 2 factorial design was applied where two dietary lipid (4-17% DM) and two dietary protein (below and above the requirement levels, 48 and 54% DM) levels were tested in juveniles for 114 d. Growth performance was not improved by the increase in dietary fat, irrespectively of the dietary protein levels. Protein retention was similar among the diets, although fish fed the diets with high lipid content resulted in significantly lower protein gain. Among the enzymes involved in amino acid catabolism, only aspartate aminotransferase activity in the liver was affected by the dietary lipid levels, being stimulated in fish fed high-lipid diets. Moreover, phosphofructokinase 1 activity was significantly elevated in the muscle of Senegalese sole fed 4% lipid diets, suggesting enhanced glycolysis in the muscle when the dietary lipid supply was limited and dietary starch increased. The results confirmed that high-lipid diets do not enhance growth, and data from the selected enzymes support the assumption that lipids are not efficiently used for energy production and protein sparing, even when dietary protein is below the protein requirement of the species. Furthermore, data suggest a significant role of glucose as the energy source in Senegalese sole.
- The supplementation of a microdiet with crystalline indispensable amino-acids affects muscle growth and the expression pattern of related genes in Senegalese sole (Solea senegalensis) larvaePublication . Canada, Paula; Engrola, S.; Mira, Sara; Teodósio, Rita; Fernandes, Jorge M. O.; Sousa, Vera; Barriga-Negra, Lúcia; Conceicao, Luis; Valente, Luisa M. P.The full expression of growth potential in fish larvae largely depends on an efficient protein utilization, which requires that all the indispensable amino acids (IAAs) are provided at an optimum ratio. The effect of supplementing a practical microdiet with encapsulated crystalline-AA to correct possible IAA deficiencies was evaluated in Senegalese sole larvae. Two isonitrogenous and isoenergetic microdiets were formulated and processed to have approximately the same ingredients and proximate composition. The control diet (CTRL) was based on protein sources commonly used in the aquafeed industry. In the supplemented diet (SUP) 8% of an encapsulated fish protein hydrolysate was replaced by crystalline-AA in order to increase the dietary IAA levels. The microdiets were delivered from mouth-opening upon a co-feeding regime until 51 days after hatching (DAH). The larvae capacity to utilize protein was evaluated using an in vivo method of controlled tube-feeding during relevant stages throughout development: pre-metamorphosis (13 DAH); metamorphosis climax (19 DAH) and metamorphosis completion (25 DAH). Somatic growth was monitored during the whole trial. A possible effect on the regulation of muscle growth was evaluated through muscle cellularity and the expression of related genes (myf5, myod2, myogenin, mrf4, myhc and mstn1) at metamorphosis climax (19 DAH) and at a juvenile stage (51 DAH). The SUP diet had a negative impact on larvae somatic growth after the metamorphosis, even though it had no effect on the development of Senegalese sole larvae capacity to retain protein. Instead, changes in somatic growth may reflect alterations on muscle growth regulation, since muscle cellularity suggested delayed muscle development in the SUP group at 51 DAH. Transcript levels of key genes regulating myogenesis changed between groups, during the metamorphosis climax and at the 51 DAH. The group fed the SUP diet had lower dnmt3b mRNA levels compared to the CTRL group. Further studies are needed to ascertain whether this would possibly lead to an overall DNA hypomethylation in skeletal muscle. (C) 2016 Elsevier B.V. All rights reserved.