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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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ISSN 0044-8486 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1712
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Auteur (up) Rodde, C.; Vandeputte, M.; Allal, F.; Besson, M.; Clota, F.; Vergnet, A.; Benzie, J.A.H.; de Verdal, H.
Titre Population, Temperature and Feeding Rate Effects on Individual Feed Efficiency in European Sea Bass (Dicentrarchus labrax) Type Article scientifique
Année 2020 Publication Revue Abrégée Front. Mar. Sci.
Volume 7 Numéro Pages
Mots-Clés Aquaculture; Fasting tolerance; feed efficiency; Feeding rate; Individual rearing; Sea bass
Résumé Using breeding programs to improve feed efficiency, the ratio between fish body weight gain (BWG) and feed intake (FI), could increase aquaculture sustainability through reduced feed costs and environmental impact. To this end, individual phenotypic information is required. Individual FI can be measured by isolating each fish. Under these conditions, restricting the feeding rate has proved relevant to improve feed efficiency indirectly by selecting faster-growing animals. Moreover, a restricted feeding rate reduces the work load of collecting uneaten pellets after each meal. The approach assumes the most efficient fish at high and low feeding rates are the same, but this assumption remains untested. In European sea bass (Dicentrarchus labrax), feed efficiency is likely to be impacted also by population, temperature, and their interaction, as already demonstrated for growth in this species. To investigate these issues, 200 European sea bass from three wild populations, Atlantic (AT), West Mediterranean (WM) and East Mediterranean (EM), were reared individually at two temperatures, 18°C and 24°C. Their BWG and FI were measured at six different feeding rates, from ad libitum (100% ADL) down to fasting. A trade-off between performance at 100% ADL and at fasting was observed: more efficient fish at 100% ADL showed a stronger decrease in BWG (standardized to metabolic weight) when the feeding rate was progressively lowered and lost more weight at fasting. The most efficient fish were not the same depending on the feeding rate, suggesting the feeding rate used to phenotype fish in selective breeding programs must be the same as that used in commercial practices. The slope in the linear relationship between BWG and FI (both standardized to metabolic weight) was similar among populations and temperatures. However, EM fish had a higher intercept than others, suggesting this population grew more and thus was more efficient for an equal feeding rate. Similarly, fish reared at 18°C were more efficient for an equal feeding rate. When feed efficiency was studied in fish fed at 100% ADL, the temperature effect disappeared but the population effect remained. This highlights the complex interplay between population, temperature and feeding rate when evaluating individual feed efficiency.
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ISSN 2296-7745 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2878
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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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