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
Date 2017-02
Language English
Author(s) Alix Maud2, Blondeau-Bidet Eva3, Grousset Evelyse1, Shiranghi Ainaz, Vergnet Alain4, Guinand Bruno1, Chatain Beatrice4, Boulo VivianeORCID4, Lignot Jehan-Herve1
Source Aquaculture (0044-8486) (Elsevier), 2017-02 , Vol. 468 , N. Part.1 , P. 314-325
DOI 10.1016/j.aquaculture.2016.10.016
WOS© Times Cited 1
Abstract 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 on these physiological data and genetic selection.
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Alix Maud, Blondeau-Bidet Eva, Grousset Evelyse, Shiranghi Ainaz, Vergnet Alain, Guinand Bruno, Chatain Beatrice, Boulo Viviane, Lignot Jehan-Herve (2017). 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. Aquaculture, 468(Part.1), 314-325. Publisher's official version : https://doi.org/10.1016/j.aquaculture.2016.10.016 , Open Access version : https://archimer.ifremer.fr/doc/00354/46521/