Marker assisted selection for resistance against viral nervous necrosis in European seabass (Dicentrarchus labrax)

publishedVersio

Effects of high‐level fishmeal replacement by plant proteins supplemented with different levels of lysine on growth performance and incidence of systemic noninfectious granulomatosis in meagre (Argyrosomus regius)

The potential use of plant protein (PP) blends (soybean, wheat, rapeseed, corn gluten and wheat gluten) in the diet of juvenile meagre (Argyrosomus regius) was investigated at increasing levels to replace fishmeal (FM) (33% and 56%) in six isonitrogenous (480 g/kg) and isoenergetic (22 MJ/kg) diets, which were supplemented with crystalline lysine. Meagre juveniles (36 ± 0.6 g initial weight) were reared in triplicate for 60 days at 19.4 ± 2.4°C to evaluate their growth performance, feed utilization parameters, body proximate composition and the prevalence of systemic noninfectious granulomatosis. Results indicated that there was no significant difference (GLM ANOVA, p > 0.05) in growth performance and feed utilization parameters in meagre fed the diet containing 300 g/kg FM (33% FM replacement) compared to the control group (450 g/kg FM inclusion), although a trend showing inferior body gain and feed conversion ratio was observed. However, higher levels of FM replacement (56%) by PP blends (200 g/kg FM inclusion) significantly impaired growth performance, feed conversion and protein efficiency rates (p 0.05). The aetiology of granulomatosis found in different tissues was not due to the presence of bacteria, as no bacterial structures were detected in histological slides when samples were stained with the Gram, Ziehl‐Neelsen and Fite‐Faraco staining. The presence of chronic systemic noninfectious granulomatosis was observed in meagre from all the experimental groups regardless the level of FM replacement by PP blends, indicating that the onset and progression of granulomatosis occurred insidiously at earlier life stages of meagre and persisted at variable levels thereafter. The liver and kidney were found to be the most severely affected tissues.info:eu-repo/semantics/acceptedVersio

Genetic Basis for Resistance Against Viral Nervous Necrosis: GWAS and Potential of Genomic Prediction Explored in Farmed European Sea Bass (Dicentrarchus labrax)

Viral nervous necrosis (VNN) is an infectious disease caused by the red-spotted grouper nervous necrosis virus (RGNNV) in European sea bass and is considered a serious concern for the aquaculture industry with fry and juveniles being highly susceptible. To understand the genetic basis for resistance against VNN, a survival phenotype through the challenge test against the RGNNV was recorded in populations from multiple year classes (YC2016 and YC2017). A total of 4,851 individuals from 181 families were tested, and a subset (n∼1,535) belonging to 122 families was genotyped using a ∼57K Affymetrix Axiom array. The survival against the RGNNV showed low to moderate heritability with observed scale estimates of 0.18 and 0.25 obtained using pedigree vs. genomic information, respectively. The genome-wide association analysis showed a strong signal of quantitative trait loci (QTL) at LG12 which explained ∼33% of the genetic variance. The QTL region contained multiple genes (ITPK1, PLK4, HSPA4L, REEP1, CHMP2, MRPL35, and SCUBE) with HSPA4L and/or REEP1 genes being highly relevant with a likely effect on host response in managing disease-associated symptoms. The results on the accuracy of predicting breeding values presented 20–43% advantage in accuracy using genomic over pedigree-based information which varied across model types and applied validation schemes.publishedVersio

Genetic Basis for Resistance Against Viral Nervous Necrosis: GWAS and Potential of Genomic Prediction Explored in Farmed European Sea Bass (Dicentrarchus labrax)

International audienceViral nervous necrosis (VNN) is an infectious disease caused by the red-spotted grouper nervous necrosis virus (RGNNV) in European sea bass and is considered a serious concern for the aquaculture industry with fry and juveniles being highly susceptible. To understand the genetic basis for resistance against VNN, a survival phenotype through the challenge test against the RGNNV was recorded in populations from multiple year classes (YC2016 and YC2017). A total of 4,851 individuals from 181 families were tested, and a subset (n∼1,535) belonging to 122 families was genotyped using a ∼57K Affymetrix Axiom array. The survival against the RGNNV showed low to moderate heritability with observed scale estimates of 0.18 and 0.25 obtained using pedigree vs. genomic information, respectively. The genome-wide association analysis showed a strong signal of quantitative trait loci (QTL) at LG12 which explained ∼33% of the genetic variance. The QTL region contained multiple genes ( ITPK1 , PLK4 , HSPA4L , REEP1 , CHMP2 , MRPL35 , and SCUBE ) with HSPA4L and/or REEP1 genes being highly relevant with a likely effect on host response in managing disease-associated symptoms. The results on the accuracy of predicting breeding values presented 20–43% advantage in accuracy using genomic over pedigree-based information which varied across model types and applied validation schemes

Genomic Selection and Genome-Wide Association Analysis for Stress Response, Disease Resistance and Body Weight in European Seabass

The majority of the genetic studies in aquaculture breeding programs focus on commercial traits such as body weight, morphology, and resistance against diseases. However, studying stress response in European seabass may contribute to the understanding of the genetic component of stress and its future use to select broodstock whose offspring may potentially be less affected by handling. A total of 865 European seabass offspring were used to measure body weight and stress response. Moreover, a disease challenge experiment with Vibrio anguillarum was conducted in a subset (332) of the above fish to study disease resistance. Fish were genotyped with a 57k SNP array, and a Genome-Wide Association study (GWAS) was performed. Five SNPs were found to be statistically significant, three of which affect stress indicators and body weight (in a subgroup of the population), and a putative SNP affects growth performance, while no SNP associated with resistance to Vibrio was found. A moderate to high genomic heritability regarding stress indicators and body weight was estimated using the Restricted Maximum Likelihood (REML) process. Finally, the accuracy, along with the correlation between Estimated Breeding Values (EBVs) and Genomic Estimated Breeding Values (GEBVs), were calculated for all the traits