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Auteur (up) Alix, M.; Blondeau-Bidet, E.; Grousset, E.; Shiranghi, A.; Vergnet, A.; Guinand, B.; Chatain, B.; Boulo, V.; Lignot, J.-H.
Titre Effects of fasting and re-alimentation on gill and intestinal morphology and indicators of osmoregulatory capacity in genetically selected sea bass (Dicentrarchus labrax) populations with contrasting tolerance to fasting Type Article scientifique
Année 2017 Publication Revue Abrégée Aquaculture
Volume 468 Numéro Pages 314-325
Mots-Clés bream sparus-auratus; dietary-sodium chloride; Enterocyte; Fasting; feed deprivation; fish; fresh-water; fundulus-heteroclitus; Gill ionocyte; Morphometry; Ontogeny; oreochromis-mossambicus; Osmoregulation; rainbow-trout; Re-alimentation; Salinity; Sea bass
Résumé Fasting and refeeding occur naturally in predators but this is largely ignored when dealing with farmed fish. Therefore,the effects of 3-week fasting and re-alimentation (2.5% of the individual body mass) were investigated using two genetically selected populations (F2 generation) of 250 g juvenile sea bass (Dicentrarchus labrax L.). Blood osmolarity, gill and intestinal morphology and expression of the sodium pump (Na+, K+-ATPase, NKA) were studied on two phenotypes showing different degrees of body mass loss during food deprivation: one group losing body mass rapidly during fasting (F+) and the other one limiting body mass loss during the same period (F-). Blood osmotic pressure significantly decreases due to re-alimentation in both groups, but this is compensated in the F+ group. In this group, gill ionocytes are smaller and less numerous, but a significantly higher NKA gene expression is noted in the gills in comparison to the F- individuals 48 and 72 h after re-alimentation, and also in the posterior intestine 72 h after re-alimentation. This most probably occurs to compensate for a higher salt intake during nutrient absorption in comparison to the F- group. Furthermore, refed F- fish absorb more lipids along the proximal anterior intestine, and take longer to digest than the F+ group, and show enterocyte vacuolization in the posterior intestine. Therefore, the two selected populations have different postprandial digestive strategies: the F- fish optimize feed efficiency first at the cost of optimal hydromineral adjustment, while the F+ group invests in osmoregulatory performance at the expense of digestive physiology. Statement of relevance: Our paper is highly relevant to the general field of commercial aquaculture. There is an increasing number of research articles dealing with fasting and refeeding in commercial fish and how to improve fish nutrition based oh these physiological data and genetic selection. (C) 2016 Elsevier B.V. All rights reserved.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0044-8486 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1712
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Auteur (up) Viblanc, V.A.; Saraux, C.; Malosse, N.; Groscolas, R.
Titre Energetic adjustments in freely breeding-fasting king penguins: does colony density matter? Type Article scientifique
Année 2014 Publication Revue Abrégée Functional Ecology
Volume Numéro Pages
Mots-Clés body temperature; energy expenditure; fasting; heart rate; physical activity; Seabird; social density; Stress
Résumé * For seabirds that forage at sea but breed while fasting on land, successful reproduction depends on the effective management of energy stores. Additionally, breeding often means aggregating in dense colonies where social stress may affect energy budgets. * Male king penguins (Aptenodytes patagonicus) fast for remarkably long periods (up to 1·5 months) while courting and incubating ashore. Although their fasting capacities have been well investigated in captivity, we still know very little about the energetics of freely breeding birds. * We monitored heart rate (HR, a proxy to energy expenditure), body temperature and physical activity of male king penguins during their courtship and first incubation shift in a colony of some 24 000 freely breeding pairs. Males were breeding either under low but increasing colony density (early breeders) or at high and stable density (late breeders). * In early breeders, daily mean and resting HR decreased during courtship but increased again 3 days before egg laying and during incubation. In late breeders, HR remained stable throughout this same breeding period. Interestingly, the daily increase in resting HR we observed in early breeders was strongly associated with a marked increase in colony density over time. This finding remained significant even after controlling for climate effects. * In both early and late breeders, courtship and incubation were associated with a progressive decrease in physical activity, whereas core body temperature remained unchanged. * We discuss the roles of decreased physical activity and thermoregulatory strategies in sustaining the long courtship–incubation fast of male king penguins. We also draw attention to a potential role of conspecific density in affecting the energetics of breeding-fasting seabirds, that is, a potential energy cost to coloniality.
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ISSN 1365-2435 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 320
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