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Ontogeny of the Digestive System of Atlantic Salmon (Salmo salar L.) and Effects of Soybean Meal from Start-Feeding.

Sahlmann C, Gu J, Kortner TM, Lein I, Krogdahl Å, Bakke AM - PLoS ONE (2015)

Bottom Line: Thus, the observed organs seemed ready to digest external feed well before the yolk sac was absorbed into the abdominal cavity.In contrast to post-smolt Atlantic salmon, inclusion of SBM did not induce intestinal inflammation in the juveniles.This indicates that SBM can be used in compound feeds for salmon fry from start-feeding to at least 144 dph and/or 4-5 g body weight.

View Article: PubMed Central - PubMed

Affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.

ABSTRACT
Despite a long history of rearing Atlantic salmon in hatcheries in Norway, knowledge of molecular and physiological aspects of juvenile development is still limited. To facilitate introduction of alternative feed ingredients and feed additives during early phases, increased knowledge regarding the ontogeny of the digestive apparatus in salmon is needed. In this study, we characterized the development of the gastrointestinal tract and accessory digestive organs for five months following hatch by using histological, biochemical and molecular methods. Furthermore, the effects of a diet containing 16.7% soybean meal (SBM) introduced at start-feeding were investigated, as compared to a fishmeal based control diet. Salmon yolk sac alevins and fry were sampled at 18 time points from hatch until 144 days post hatch (dph). Histomorphological development was investigated at 7, 27, 46, 54 and 144 dph. Ontogenetic expression patterns of genes encoding key digestive enzymes, nutrient transporters, gastrointestinal peptide hormones and T-cell markers were analyzed from 13 time points by qPCR. At 7 dph, the digestive system of Atlantic salmon alevins was morphologically distinct with an early stomach, liver, pancreas, anterior and posterior intestine. About one week before the yolk sac was internalized and exogenous feeding was started, gastric glands and developing pyloric caeca were observed, which coincided with an increase in gene expression of gastric and pancreatic enzymes and nutrient transporters. Thus, the observed organs seemed ready to digest external feed well before the yolk sac was absorbed into the abdominal cavity. In contrast to post-smolt Atlantic salmon, inclusion of SBM did not induce intestinal inflammation in the juveniles. This indicates that SBM can be used in compound feeds for salmon fry from start-feeding to at least 144 dph and/or 4-5 g body weight.

No MeSH data available.


Development of the expression of T-cell marker genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).Values are mean fold change as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: il17a, interleukin 17A; tcrγ, T cell receptor gamma. See also S2 Table for mean values and results of post-hoc one-way ANOVA with time as the main variable.
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pone.0124179.g008: Development of the expression of T-cell marker genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).Values are mean fold change as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: il17a, interleukin 17A; tcrγ, T cell receptor gamma. See also S2 Table for mean values and results of post-hoc one-way ANOVA with time as the main variable.

Mentions: The expression profiles of T cell receptor gamma (tcrγ) and interleukin 17a (il17a) showed parallel expression patterns (Fig 8, Table 3). Expression was detectable from 7 dph and showed a variable but overall increasing pattern, peaking at 67 dph before decreasing. Low expression levels comparable to 7 dph were observed at 96 and 144 dph.


Ontogeny of the Digestive System of Atlantic Salmon (Salmo salar L.) and Effects of Soybean Meal from Start-Feeding.

Sahlmann C, Gu J, Kortner TM, Lein I, Krogdahl Å, Bakke AM - PLoS ONE (2015)

Development of the expression of T-cell marker genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).Values are mean fold change as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: il17a, interleukin 17A; tcrγ, T cell receptor gamma. See also S2 Table for mean values and results of post-hoc one-way ANOVA with time as the main variable.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414279&req=5

pone.0124179.g008: Development of the expression of T-cell marker genes of juvenile Atlantic salmon as a function of time (days post hatch), differentiated by the pre-feeding period and the period following start-feeding (indicated by the vertical dotted line at 46 days post hatch) with the experimental diets (fishmeal or soybean meal diets).Values are mean fold change as compared to the respective time point of first detection; n = 3 pooled samples of 3 individual fish per tank (three tanks per diet) with standard error represented by vertical bars. Abbreviations: il17a, interleukin 17A; tcrγ, T cell receptor gamma. See also S2 Table for mean values and results of post-hoc one-way ANOVA with time as the main variable.
Mentions: The expression profiles of T cell receptor gamma (tcrγ) and interleukin 17a (il17a) showed parallel expression patterns (Fig 8, Table 3). Expression was detectable from 7 dph and showed a variable but overall increasing pattern, peaking at 67 dph before decreasing. Low expression levels comparable to 7 dph were observed at 96 and 144 dph.

Bottom Line: Thus, the observed organs seemed ready to digest external feed well before the yolk sac was absorbed into the abdominal cavity.In contrast to post-smolt Atlantic salmon, inclusion of SBM did not induce intestinal inflammation in the juveniles.This indicates that SBM can be used in compound feeds for salmon fry from start-feeding to at least 144 dph and/or 4-5 g body weight.

View Article: PubMed Central - PubMed

Affiliation: Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.

ABSTRACT
Despite a long history of rearing Atlantic salmon in hatcheries in Norway, knowledge of molecular and physiological aspects of juvenile development is still limited. To facilitate introduction of alternative feed ingredients and feed additives during early phases, increased knowledge regarding the ontogeny of the digestive apparatus in salmon is needed. In this study, we characterized the development of the gastrointestinal tract and accessory digestive organs for five months following hatch by using histological, biochemical and molecular methods. Furthermore, the effects of a diet containing 16.7% soybean meal (SBM) introduced at start-feeding were investigated, as compared to a fishmeal based control diet. Salmon yolk sac alevins and fry were sampled at 18 time points from hatch until 144 days post hatch (dph). Histomorphological development was investigated at 7, 27, 46, 54 and 144 dph. Ontogenetic expression patterns of genes encoding key digestive enzymes, nutrient transporters, gastrointestinal peptide hormones and T-cell markers were analyzed from 13 time points by qPCR. At 7 dph, the digestive system of Atlantic salmon alevins was morphologically distinct with an early stomach, liver, pancreas, anterior and posterior intestine. About one week before the yolk sac was internalized and exogenous feeding was started, gastric glands and developing pyloric caeca were observed, which coincided with an increase in gene expression of gastric and pancreatic enzymes and nutrient transporters. Thus, the observed organs seemed ready to digest external feed well before the yolk sac was absorbed into the abdominal cavity. In contrast to post-smolt Atlantic salmon, inclusion of SBM did not induce intestinal inflammation in the juveniles. This indicates that SBM can be used in compound feeds for salmon fry from start-feeding to at least 144 dph and/or 4-5 g body weight.

No MeSH data available.