Genotype x nutrition interactions in European sea bass (Dicentrarchus labrax): effects on gut health and intestinal microbiota

One of the main objectives of the present study was an effective replacement of dietary fishmeal/fish oil (FM/FO) by new raw materials without negatively affecting European sea bass (Dicentrarchus labrax) performance and health status within a selection breeding context. The genomic selection of this species is still in its infancy if compared to salmonids and in particular, the role of D.labrax genome in shaping the gut microbiome, has been scarcely investigated. Wildtype (WT) and selected (GS) sea bass were fed with two diets: a control (20% FM/ 5–9% FO), and a “future” (F) diet, in which FM was decreased to 10% being replaced by poultry meal, whereas FO was completely replaced by a blend of rapeseed, poultry, and algae oils. The morphological evaluation of the intestine revealed a well-organized folding pattern and a conserved gut epithelial barrier for all fish groups. Despite a basal level of inflammation in the proximal intestine of WT fish, no differences were observed neither in the morphometric characteristics of goblet cells nor in the expression of GALT-related genes in response to fish genotype or diet. At distal intestine, WT fish showed a higher inflammatory status and larger goblet cells than GS fish and within the same genotype, fish fed the F diet had in general larger goblet cells. In distal intestine, a significant effect was found on the expression of 3 out of 7 target GALT genes. In particular, the expression of cytokines il-1β, tnf-α, and il-10 was different, showing an interaction effect diet x genotype. Diet had a lower influence upon gut bacterial composition than genotype. Indeed, regardless of the diet, WT fish showed higher species richness than GS genotype and this could be a direct consequence of selective breeding for multiple traits selection including growth, external morphology for lower abdominal fat deposition and adaptation to multiple and successive feed sources and composition across generations of selection. Furthermore, the gut microbiota of GS fish shared a reduced individual variability, indicating an enhanced capacity to cope with changes in diet composition. The less changes of GS sea bass at the level of gut bacterial composition in cumulating data collected with the feeds, demonstrate a capacity to reshape their microbiota thus better adapting to the diet, but with no negative impact on their growth performances, and even a better growth. A significant genotype effect was found for specific bacterial taxa, such as Paracoccus genus and other genera belonging to Moraxellaceae family, which were enriched in WT fish, regardless of the diet. Interestingly, the relative abundance of Paracoccus genus was positively correlated with higher proinflammatory cytokine il-1β expression found in distal intestine of wildtype sea bass

Functional additives in a selected european sea bass (Dicentrarchus labrax) genotype: effects on the stress response and gill antioxidant response to hydrogen peroxide (H2O2) treatment.

Husbandry practices in aquaculture production may lead to stress processes and oxidative stress damages on fish tissues. Functional ingredients have profiled as suitable candidates for reinforcing the fish antioxidant response and stress tolerance. In addition, selective breeding strategies have also demonstrated a correlation between fish growth and stress reactiveness, which may be a key component in species domestication. The present study evaluates the potential of three different functional additives for gill endogenous antioxidant capacity and stress relief in a growth selected genotype of European sea bass (Dicentrarchus labrax) juveniles fed low-FM/FO diets. For this purpose, after 72 days of a feeding trial, all fish were subjected to an oxidative stress challenge consisting of a 1 h bath exposure to hydrogen peroxide (H2O2 ) at a total concentration of 50 ppm. The functional additives induced a better recovery from the stress process, with a higher reduction in fish circulating plasma cortisol 24 h after oxidative stress. In addition, the functional additives induced higher catalase gill gene expression in response to the oxidative stress insult

Nutritional innovations in superior European sea bass (Dicentrarchus labrax) genotypes: implications on fish performance and feed utilization.

The sustainable development of the aquaculture industry relies on the use of alternative conventional and emergent raw materials that contributes to a circular economy and to reduce the dependency on fish meals and fish oils coming from oceanic fish populations. Additionally, the genetic selection of farmed fish that can display higher growth and feed utilization when fed alternative feeds, is pointed out to be a complementary valuable tool to facilitate the implementation of circular economy approaches. The main purpose of the present study was to determine the effectiveness of genetic selection for growth in European sea bass, in response to a challenge with an alternative diet that aimed to partially replaced fishmeal (FM) by poultry meal (PM) and totally replace fish oil (FO) by a blend of poultry oil (PO) with a novel microalgae oil. The two families of fish juveniles were obtained by in vitro fertilization of selected for a multi-trait including high growth (genetically selected, GS) or nonselected (wild type, WT) broodstocks and then were nutritionally challenged with a control diet that mirrored a standard commercial diet with fishmeal (20%) and fish oil (7%), or a Future diet that partially replaced the FM by PM and totally replaced the FO by a blend of rapeseed oil, PO, and a novel DHA rich-algal oil. From the second month of feeding until the end of the trial, European sea bass that was selected since for 7 generations performed better in terms of growth than the wild-type genotype, possibly related with an apparent favored feed and nutrient utilization. Furthermore, selection decreased the perivisceral fat and increased the nutritional value of flesh by increasing DHA (in g/ 100 g flesh) and ARA contents. In contrast, the dietary treatment showed little effect on fish growth performance, denoting the successful partial replacement of FM by PM and the total replacement of FO by a blend of poultry oil and an emergent microalgal oil. However, Future diet tended to reduce the ADCs of some amino acids, as well as showed an additive effect to genotype in increasing the n-3 PUFA of flesh. Altogether, our data demonstrate that multi-trait genetic selection of European sea bass improve fish plasticity to cope with the variations of ingredients in alternative feeds with low FM/FO

Genetically superior European sea bass (Dicentrarchus labrax) and nutritional innovations: Effects of functional feeds on fish immune response, disease resistance, and gut microbiota

The objective of this study was to determine if selected fish genotypes could benefit from the use of functional additives in novel aqua feed formulations to improve growth performance, gut microbiota, immune response, and disease resistance in fish. Two batches of juvenile European sea bass selected for high growth (HG; selected sires x selected dams), and wild types (WT; wild sires x selected females) were fed a “future diet” coated with three different functional additives for 12 weeks as follows: (i) 2 weeks with a high dose, followed by (ii) 10 weeks with a low dose. The functional additives tested were a mixture of probiotics (PROB), organic acids (ORG), and phytogens (PHYTO). A pathogen challenge test (Vibrio anguillarum) and a stress condition (overcrowding) were performed after each dose. At the end of the feeding experiment, fish from the HG group performed better than fish from the WT group in terms of body weight, relative growth, SGR, and DGI. The results of the two challenge tests performed after two weeks of high dose and ten weeks of low dose showed a significant effect of diet on fish survival. GALT-associated gene expression analysis revealed an interaction between the genotype and diet for il-1β in the distal gut. Finally, regarding the gut microbiota, discriminant analysis showed no clear separation between fish fed the future diet and those fed the same diet with experimental additives. Nevertheless, the relative abundance of certain taxa varied between experimental groups. For example, fish fed the ORG diet had higher relative abundance of Streptococcus in both genotypes, whereas fish fed the PHYTO diet had higher abundance of Lactobacillales. In contrast, fish fed PROB had lower bundance of Pseudomonas and Acinetobacter

Revue bibliographique. L'amélioration génétique de la carpe commune (Cyprinus carpio L.) : état des connaissances

La carpe commune, dont l'aire d'élevage s'étend sur les 2 hémisphères, est l'espèce de poisson la plus anciennement domestiquée par l'homme. Nombreux sont les travaux scientifiques et notamment de génétique qui s'y réfèrent. Les méthodes de génétique des populations ont permis de définir le niveau de variabilité génétique. Cette caractérisation des stocks d'élevage et sauvages permet premièrement d'optimiser le choix des souches en fonction des objectifs zootechniques et deuxièmement la mise en oeuvre de schémas d'amélioration génétique plus performants par l'utilisation de marqueurs électrophorétiques. Les rares études biochimiques effectuées jusqu'à présent ont montré le haut niveau de consanguinité de certaines souches captives et les effets négatifs qui en résultent sur les performances d'élevage (sensibilité aux maladies). On admet que, pour de telles souches, des plateaux de sélection sont atteints pour les caractéristiques de croissance. En l'absence de progrès génétique constaté suite aux expériences de sélection individuelle, les principaux schémas de sélection pratiqués chez la carpe sont donc basés sur des croisements intraspécifiques efficaces pour améliorer la croissance, la résistance à l'hydropisie infectieuse et la résistance au froid. Cependant, la sélection familiale est susceptible de fournir d'intéressants résultats, mais cette voie reste à explorer. La création de cheptels monosexes femelles diploïdes ou triploïdes est maintenant bien au point. Par contre, leurs caractéristiques d'élevage sont encore à éprouver. Enfin tout récemment, la méthodologie de la transgénèse chez les poissons a été testée avec succès avec la carpe commune

Revue bibliographique. L'amélioration génétique de la carpe commune (Cyprinus carpio L.) : état des connaissances

La carpe commune, dont l'aire d'élevage s'étend sur les 2 hémisphères, est l'espèce de poisson la plus anciennement domestiquée par l'homme. Nombreux sont les travaux scientifiques et notamment de génétique qui s'y réfèrent. Les méthodes de génétique des populations ont permis de définir le niveau de variabilité génétique. Cette caractérisation des stocks d'élevage et sauvages permet premièrement d'optimiser le choix des souches en fonction des objectifs zootechniques et deuxièmement la mise en oeuvre de schémas d'amélioration génétique plus performants par l'utilisation de marqueurs électrophorétiques. Les rares études biochimiques effectuées jusqu'à présent ont montré le haut niveau de consanguinité de certaines souches captives et les effets négatifs qui en résultent sur les performances d'élevage (sensibilité aux maladies). On admet que, pour de telles souches, des plateaux de sélection sont atteints pour les caractéristiques de croissance. En l'absence de progrès génétique constaté suite aux expériences de sélection individuelle, les principaux schémas de sélection pratiqués chez la carpe sont donc basés sur des croisements intraspécifiques efficaces pour améliorer la croissance, la résistance à l'hydropisie infectieuse et la résistance au froid. Cependant, la sélection familiale est susceptible de fournir d'intéressants résultats, mais cette voie reste à explorer. La création de cheptels monosexes femelles diploïdes ou triploïdes est maintenant bien au point. Par contre, leurs caractéristiques d'élevage sont encore à éprouver. Enfin tout récemment, la méthodologie de la transgénèse chez les poissons a été testée avec succès avec la carpe commune

Study of tissues mapping and flesh quality of brown trout by color image analysis

International audienceWith the Trade Union of the French Poultry and Aquacole Selectors (SYSAAF) and French National Institute of Agronomical Research (INRA) we studied the farmed brown sea-trout development according to genetic improvement and feeding composition by color image analysis. They want to value the effects of feeding which contains various levels of lipid. In this research project a vision system was devised to research and measure brown trout visual features. Various segmentation methods were applied to locate various tissues of brown trout cutlets and to measure their area and color. The results obtained on fish flesh by the image analysis were compared with chemical measurements of fat and with NMR measurements. The color image features provide data on the development of various tissues and the effect of feeding on morphological development can be tested on efficient aspect variable