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    ABSTRACT: Improving feed efficiency is a major goal in poultry production in order to reduce production costs, increase the possibility of using alternative feedstuffs and decrease the volume of manure. However, in spite of their economic and environmental impact, very few quantitative trait loci (QTL) have been reported on these traits. Thus, we undertook the detection of QTL on 820 meat-type chickens from a F2 cross between D− and D+ lines that were divergently selected on low or high digestive efficiency at 3 weeks of age. Birds were measured for growth between 0 and 23 days, feed intake and feed conversion ratio between 9 and 23 days, breast and abdominal fat yields at 23 days, and the anatomy of their digestive tract (density, relative weight and length of the duodenum, jejunum, ileum, and ratio of proventriculus to gizzard weight) was examined. To evaluate excretion traits, fresh and dry weight, water content, pH, nitrogen to phosphorus ratio from 0 to 23 days, and pH of gizzard and jejunum contents at 23 days were measured. A set of 3379 single nucleotide polymorphisms distributed on 28 Gallus gallus (GGA) autosomes, the Z chromosome and one unassigned linkage group was used for QTL detection. Using the QTLMap software developed for linkage analyses by interval mapping, we detected 16 QTL for feed intake, 13 for feed efficiency, 49 for anatomy-related traits, seven for growth, six for body composition and ten for excretion. Nine of these QTL were genome-wide significant (four for feed intake on GGA1, one for feed efficiency on GGA2, and four for anatomy on GGA1, 2, 3 and 4). GGA16, 19, and 26 carried many QTL for different types of traits that co-localize at the same position. This study identified several QTL regions that are involved in the control of digestive efficiency in chicken. Further studies are needed to identify the genes that underlie these effects, and to validate these in other commercial populations and for different breeding environments.
    Full-text · Article · Sep 2015 · Genetics Selection Evolution
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    ABSTRACT: Genetic selection for enhanced growth rate in meat-type chickens (Gallus domesticus) is usually accompanied by excessive adiposity, which has negative impacts on both feed efficiency and carcass quality. Enhanced visceral fatness and several unique features of avian metabolism (i.e., fasting hyperglycemia and insulin insensitivity) mimic overt symptoms of obesity and related metabolic disorders in humans. Elucidation of the genetic and endocrine factors that contribute to excessive visceral fatness in chickens could also advance our understanding of human metabolic diseases. Here, RNA sequencing was used to examine differential gene expression in abdominal fat of genetically fat and lean chickens, which exhibit a 2.8-fold divergence in visceral fatness at 7 wk. Ingenuity Pathway Analysis revealed that many of 1687 differentially-expressed genes are associated with hemostasis, endocrine function and metabolic syndrome in mammals. Among the highest expressed genes in abdominal fat, across both genotypes, were 25 differentially-expressed genes associated with de novo synthesis and metabolism of lipids. Over-expression of numerous adipogenic and lipogenic genes in the FL chickens suggests that in situ lipogenesis in chickens could make a more substantial contribution to expansion of visceral fat mass than previously recognized. Distinguishing features of the abdominal fat transcriptome in lean chickens were high abundance of multiple hemostatic and vasoactive factors, transporters, and ectopic expression of several hormones/receptors, which could control local vasomotor tone and proteolytic processing of adipokines, hemostatic factors and novel endocrine factors. Over-expression of several thrombogenic genes in abdominal fat of lean chickens is quite opposite to the pro-thrombotic state found in obese humans. Clearly, divergent genetic selection for an extreme (2.5-2.8-fold) difference in visceral fatness provokes a number of novel regulatory responses that govern growth and metabolism of visceral fat in this unique avian model of juvenile-onset obesity and glucose-insulin imbalance.
    Full-text · Article · Sep 2015 · PLoS ONE
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    ABSTRACT: Using targeted genetical genomics, a QTL affecting the initial post-mortem pH value of chicken breast muscle (Pectoralis major) on chromosome 1 (GGA1) was recently fine-mapped. Thirteen genes were present in the QTL region of about 1 Mb. In this study, ten birds that were inferred to be homozygous for either the high (QQ) or low (qq) QTL allele were selected for re-sequencing. After enrichment for 1 Mb around the QTL region, > 500 x coverage for the QTL region in each of the ten birds was obtained. In total 5056 SNPs were identified for which the genotypes were consistent with one of the QTL genotypes. We used custom tools to identify putative causal mutations in the mapped QTL region from these SNPs. Four non-synonymous SNPs differentiating the two QTL genotype groups were identified within four local genes (PRDX4, EIF2S3, PCYT1B and E1BTD2). While these are likely candidate SNPs to explain the QTL effect, 54 additional consensus SNPs were detected within gene-related regions (UTR regions, splicing sites CpG island and promoter regions) for the QQ birds and 71 for the qq birds. These could also play a role explaining the observed QTL effect. The results provide an important step for prioritizing among a large amount of candidate mutations and significantly contribute to the understanding of the genetic mechanisms affecting the initial post-mortem pH value of chicken muscle. Copyright © 2015 Author et al.
    Full-text · Article · Aug 2015 · G3-Genes Genomes Genetics
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    ABSTRACT: Feed efficiency and its digestive component, digestive efficiency, are key factors in the environmental impact and economic output of poultry production. The interaction between the host and intestinal microbiota has a crucial role in the determination of the ability of the bird to digest its food and to the birds’ feed efficiency. We therefore investigated the phenotypic and genetic relationships between birds’ efficiency and the composition of the cecal microbiota in a F2 cross between broiler lines divergently selected for their high or low digestive efficiency.
    Full-text · Article · Aug 2015 · PLoS ONE
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    ABSTRACT: The increasing use of unconventional feedstuffs in chicken’s diets results in the substitution of starch by lipids as the main dietary energy source. To evaluate the responses of genetically fat or lean chickens to these diets, males of two experimental lines divergently selected for abdominal fat content were fed isocaloric, isonitrogenous diets with either high lipid (80 g/kg), high fiber (64 g/kg) contents (HL), or low lipid (20 g/kg), low fiber (21 g/kg) contents (LL) from 22 to 63 days of age. The diet had no effect on growth performance and did not affect body composition evaluated at 63 days of age. Glycolytic and oxidative energy metabolisms in the liver and glycogen storage in liver and Sartorius muscle at 63 days of age were greater in chicken fed LL diet compared with chicken fed HL diet. In Pectoralis major (PM) muscle, energy metabolisms and glycogen content were not different between diets. There were no dietary-associated differences in lipid contents of the liver, muscles and abdominal fat. However, the percentages of saturated (SFA) and monounsaturated fatty acids (MUFA) in tissue lipids were generally higher, whereas percentages of polyunsaturated fatty acids (PUFA) were lower for diet LL than for diet HL. The fat line had a greater feed intake and average daily gain, but gain to feed ratio was lower in that line compared with the lean line. Fat chickens were heavier than lean chickens at 63 days of age. Their carcass fatness was higher and their muscle yield was lower than those of lean chickens. The oxidative enzyme activities in the liver were lower in the fat line than in the lean line, but line did not affect energy metabolism in muscles. The hepatic glycogen content was not different between lines, whereas glycogen content and glycolytic potential were higher in the PM muscle of fat chickens compared with lean chickens. Lipid contents in the liver, muscles and abdominal fat did not differ between lines, but fat chickens stored less MUFA and more PUFA in abdominal fat and muscles than lean chickens. Except for the fatty acid composition of liver and abdominal fat, no interaction between line and diet was observed. In conclusion, the amount of lipids stored in muscles and fatty tissues by lean or fat chickens did not depend on the dietary energy source.
    No preview · Article · May 2015 · animal
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    ABSTRACT: Very few causal genes have been identified by quantitative trait loci (QTLs) mapping because of the large size of QTLs, and most of them were identified thanks to functional links already known with the targeted phenotype. Here we propose to combine selection signature detection, coding SNP annotation, and cis-expression QTL analyses to identify potential causal genes underlying QTLs identified in divergent line designs. As a model, we chose experimental chicken lines divergently selected for only one trait, the abdominal fat weight, in which several QTLs were previously mapped. Using a new haplotype-based statistics exploiting the very high SNP density generated through whole genome re-sequencing, we found 129 significant selective sweeps. Most of the QTLs co-localized with at least one sweep, which markedly narrowed candidate region size. Some of those sweeps contained only one gene, therefore making them strong positional causal candidates with no presupposed function. We then focused on two of these QTLs/sweeps. The absence of non-synonymous SNPs in their coding regions strongly suggests the existence of causal mutations acting in cis on their expression, confirmed by cis-eQTL identification using either allele-specific expression or genetic mapping analyses. Additional expression analyses on those two genes in the chicken and mice contrasted for adiposity reinforces their link with this phenotype. This study shows for the first time the interest of combining selective sweeps mapping, coding SNP annotation and cis-eQTL analyses for identifying causative genes for a complex trait, in the context of divergent lines selected for this specific trait. Moreover, it highlights two genes, JAG2 and PARK2, as new potential negative and positive key regulators of adiposity in chicken and mice. Copyright © 2015 Author et al.
    Full-text · Article · Feb 2015 · G3-Genes Genomes Genetics
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    ABSTRACT: Background Behavioral traits such as sociability, emotional reactivity and aggressiveness are major factors in animal adaptation to breeding conditions. In order to investigate the genetic control of these traits as well as their relationships with production traits, a study was undertaken on a large second generation cross (F2) between two lines of Japanese Quail divergently selected on their social reinstatement behavior. All the birds were measured for several social behaviors (social reinstatement, response to social isolation, sexual motivation, aggression), behaviors measuring the emotional reactivity of the birds (reaction to an unknown object, tonic immobility reaction), and production traits (body weight and egg production).ResultsWe report the results of the first genome-wide QTL detection based on a medium density SNP panel obtained from whole genome sequencing of a pool of individuals from each divergent line. A genetic map was constructed using 2145 markers among which 1479 could be positioned on 28 different linkage groups. The sex-averaged linkage map spanned a total of 3057 cM with an average marker spacing of 2.1 cM. With the exception of a few regions, the marker order was the same in Japanese Quail and the chicken, which confirmed a well conserved synteny between the two species. The linkage analyses performed using QTLMAP software revealed a total of 45 QTL related either to behavioral (23) or production (22) traits. The most numerous QTL (15) concerned social motivation traits. Interestingly, our results pinpointed putative pleiotropic regions which controlled emotional reactivity and body-weight of birds (on CJA5 and CJA8) or their social motivation and the onset of egg laying (on CJA19).Conclusion This study identified several QTL regions for social and emotional behaviors in the Quail. Further research will be needed to refine the QTL and confirm or refute the role of candidate genes, which were suggested by bioinformatics analysis. It can be hoped that the identification of genes and polymorphisms related to behavioral traits in the quail will have further applications for other poultry species (especially the chicken) and will contribute to solving animal welfare issues in poultry production.
    Full-text · Article · Jan 2015 · BMC Genomics
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    ABSTRACT: Excessive deposition of body fat is detrimental to production efficiency. The aim of this study was to provide plasma indicators of chickens' ability to store fat. From 3 to 9 wk of age, chickens from 2 experimental lines exhibiting a 2.5-fold difference in abdominal fat content and fed experimental diets with contrasted feed energy sources were compared. The diets contained 80 vs. 20 g of lipids and 379 vs. 514 g of starch per kg of feed, respectively, but had the same ME and total protein contents. Cellulose was used to dilute energy in the high-fat diet. At 9 wk of age, the body composition was analyzed and blood samples were collected. A metabolome-wide approach based on proton nuclear magnetic resonance spectroscopy was associated with conventional measurements of plasma parameters. A metabolomics approach showed that betaine, glutamine, and histidine were the most discriminating metabolites between groups. Betaine, uric acid, triglycerides, and phospholipids were positively correlated (r > 0.3; P < 0.05) and glutamine, histidine, triiodothyronine, homocysteine, and β-hydroxybutyrate were negatively correlated (r < -0.3; P < 0.05) with relative weight of abdominal fat and/or fat situated at the top of external face of the thigh. The combination of plasma free fatty acids, total cholesterol, phospholipid, β-hydroxybutyrate, glutamine, and methionine levels accounted for 74% of the variability of the relative weight of abdominal fat. On the other hand, the combination of plasma triglyceride and homocysteine levels accounted for 37% of the variability of fat situated at the top of external face of the thigh. The variations in plasma levels of betaine, homocysteine, uric acid, glutamine, and histidine suggest the implication of methyl donors in the control of hepatic lipid synthesis and illustrate the interplay between AA, glucose, and lipid metabolisms in growing chickens.
    No preview · Article · Jan 2015 · Journal of Animal Science
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    ABSTRACT: Abstract Text: A QTL detection was performed on birds originated from a slow-growing line selected by the SASSO breeding company since 1994. More precisely, 764 chicken and their parents (10 sires and 87 dams) were genotyped on the Illumina chicken SNP 60K Beadchip. Measures of body weight, breast meat yield, abdominal fat yield, leg yield, pH at 15 min and 24h post-slaughter, meat color (L), drip loss and intramuscular fat content were registered. Two methodologies of fine mapping were tested: a linkage disequilibrium (LD) analysis (EMMAX) and a linkage disequilibrium and linkage analysis (LDLA). With the two methodologies, we detected a significant QTL of early growth at a p-value of 5x10-5on chromosome 24. We detected also significant QTL of breast meat yield on the chromosomes 17 and 18 and a QTL of pH at 15 min post-mortem on the chromosome 13. Keywords: chicken, slow-growing line, QTL, carcass quality, meat quality
    Full-text · Conference Paper · Aug 2014
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    ABSTRACT: Abstract Text: Digestive efficiency (DE) has a large impact on excretion traits and on environmental impact of poultry production. A F2 cross between 2 lines of chickens divergently selected on DE has been used to detect QTL. A total of 865 birds were measured for the quantity of fresh and dry excreta as raw values (FEW, DEW) or as relative to consumption values (FEWC, DEWC), for water content (WC), pH (PHE) and nitrogen to phosphorus content ratio (NP) of excreta, and for pH of gizzard and jejunum contents (PHG, PHJ). Eleven QTL were found for: DEW (GGA19, GGA26), FEWC (GGA8), DEWC (GGA16), NP (GGA11, GGA26), WC (GGA28), PHG (GGA2, GGA16, GGA27), PHJ (GGA19). On chromosomes 16 and 27, QTL co-localized with QTL for DE. On chromosomes 8, 16 and 26, QTLs for excretion traits co-localized with QTLs for relative intestine length. Keywords: QTL excretion digestibility
    No preview · Conference Paper · Aug 2014
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    ABSTRACT: Abstract Text: The social behavior of animals, which is partly controlled by genetics, is involved in their adaptation to large breeding groups. Genetic relationships between different social behaviors, fear behaviors and production traits were estimated in a second generation cross of two lines of Quail divergently selected for their social reinstatement behavior. A strong genetic correlation existed between sexual and aggressive behaviors, both being significantly positively correlated to the response to the novel object test. Strong genetic correlations between behaviors and productions were also highlighted. Higher weights were genetically associated with increased emotional reactivity estimated by the duration of tonic immobility. The age at first egg was earlier in birds with high social reinstatement behavior but delayed in case of higher emotional reactivity. A higher egg production was genetically associated with a lower emotional reactivity toward a novel object but also with higher sexual and aggressive behaviors. Keywords: Social behavior, Selection, Bird
    No preview · Conference Paper · Aug 2014
  • N Alnahhas · C Berri · M Boulay · E Baéza · Y Jégo · Y Baumard · M Chabault · E Le Bihan-Duval
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    ABSTRACT: Genetic parameters for ultimate pH of Pectoralis major (PM-pHu) and Sartorius (SART-pHu) muscles, color parameters L*, a*, b*, log of drip loss (LogDL) of PM muscle, breast meat yield (BMY), thigh yield (TY), abdominal fat percentage (AFP), and body weight at 6 weeks (BW6) were estimated in two lines of broiler chickens divergently selected for PM-pHu. Effects of selection on all the previous traits and on glycolytic potential (GP), pH measured 15 minutes post-mortem (PM-pH15), curing-cooking yield (CCY), cooking loss (CL), and Warner-Bratzler shear force (WB-SF) of the PM muscle were also analyzed after five generations. Strong genetic determinism of PM-pHu was observed, with estimated h(2) of 0.57±0.02. There was a significant positive genetic correlation (rg) between PM-pHu and SART-pHu (0.54±0.04), indicating that selection had a general rather than a specific effect on energy storage in skeletal muscles. The h(2) estimates of L*, a* and b* parameters were 0.58±0.02, 0.39±0.02 and 0.48±0.02, respectively. Heritability estimates for TY, BMY and AFP were 0.39±0.04, 0.52±0.01 and 0.71±0.02, respectively. Our results indicated different genetic control of LogDL and lightness of the meat between the two lines, these traits had a strong rg with PM-pHu in the line selected for low (pHu-) pHu value (-0.80 and -0.71, respectively) which was not observed in the line selected for high (pHu+) pHu value (-0.04 and -0.29, respectively). A significant positive rg (0.21±0.04) was observed between PM-pHu and BMY, but not between PM-pHu and BW6, AFP or TY. Significant phenotypic differences were observed after 5 generations of selection between the two lines. The mean differences (P < 0.001) in ultimate pH between the two lines were 0.42 and 0.21 pH units in the breast and thigh muscle, respectively. Breast meat in the pHu+ line exhibited lower lightness (-5 units, P < 0.001), redness (-0.22 units, P < 0.001), yellowness (-1.53 units, P < 0.001), and DL (-1.6 units, P < 0.001) than in the pHu- line. Breast meat of the pHu+ line was also characterized by greater CCY (+6.1 units, P < 0.001), lower CL (-1.66 units, P < 0.01), and lower WB-SF after cooking (-5.1 units, P < 0.001) compared to the pHu- line. This study highlighted that selection based on pHu can be effective in improving the processing ability of breast meat and reducing the incidence of meat quality defects without affecting chicken growth performance.
    No preview · Article · Jul 2014 · Journal of Animal Science
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    ABSTRACT: Improving digestive efficiency is a major goal in poultry production, to reduce production costs, make possible the use of alternative feedstuffs and decrease the volume of manure produced. Since measuring digestive efficiency is difficult, identifying molecular markers associated with genes controlling this trait would be a valuable tool for selection. Detection of QTL (quantitative trait loci) was undertaken on 820 meat-type chickens in a F2 cross between D- and D+ lines divergently selected on low or high AMEn (apparent metabolizable energy value of diet corrected to 0 nitrogen balance) measured at three weeks in animals fed a low-quality diet. Birds were measured for 13 traits characterizing digestive efficiency (AMEn, coefficients of digestive utilization of starch, lipids, proteins and dry matter (CDUS, CDUL, CDUP, CDUDM)), anatomy of the digestive tract (relative weights of the proventriculus, gizzard and intestine and proventriculus plus gizzard (RPW, RGW, RIW, RPGW), relative length and density of the intestine (RIL, ID), ratio of proventriculus and gizzard to intestine weight (PG/I); and body weight at 23 days of age. Animals were genotyped for 6000 SNPs (single nucleotide polymorphisms) distributed on 28 autosomes, the Z chromosome and one unassigned linkage group. Nine QTL for digestive efficiency traits, 11 QTL for anatomy-related traits and two QTL for body weight at 23 days of age were detected. On chromosome 20, two significant QTL at the genome level co-localized for CDUS and CDUDM, i.e. two traits that are highly correlated genetically. Moreover, on chromosome 16, chromosome-wide QTL for AMEn, CDUS, CDUDM and CDUP, on chromosomes 23 and 26, chromosome-wide QTL for CDUS, on chromosomes 16 and 26, co-localized QTL for digestive efficiency and the ratio of intestine length to body weight and on chromosome 27 a chromosome-wide QTL for CDUDM were identified. This study identified several regions of the chicken genome involved in the control of digestive efficiency. Further studies are necessary to identify the underlying genes and to validate these in commercial populations and breeding environments.
    Full-text · Article · Apr 2014 · Genetics Selection Evolution
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    ABSTRACT: The enzyme β,β-carotene-15,15'-mono-oxygenase 1 (BCMO1) is responsible for the symmetrical cleavage of β-carotene into retinal. We identified a polymorphism in the promoter of the BCMO1 gene, inducing differences in BCMO1 mRNA levels (high in adenines (AA) and low in guanines (GG)) and colour in chicken breast muscle. The present study was designed to test whether this polymorphism could affect the response to dietary β-carotene. Dietary β-carotene supplementation did not change the effects of the genotypes on breast muscle properties: BCMO1 mRNA levels were lower and xanthophyll contents higher in GG than in AA chickens. Lower vitamin E levels in the plasma and duodenum, plasma cholesterol levels and body weight were also observed in GG than in AA chickens. In both genotypes, dietary β-carotene increased vitamin A storage in the liver; however, it reduced numerous parameters such as SCARB1 (scavenger receptor class B type I) in the duodenum, BCMO1 in the liver, vitamin E levels in the plasma and tissues, xanthophyll contents in the pectoralis major muscle and carcass adiposity. However, several diet × genotype interactions were observed. In the GG genotype, dietary β-carotene increased ISX (intestine-specific homeobox) and decreased BCMO1 mRNA levels in the duodenum, decreased xanthophyll concentrations in the duodenum, liver and plasma, and decreased colour index and HDL-cholesterol concentration in the plasma. Retinol accumulation following dietary β-carotene supplementation was observed in the duodenum of AA chickens only. Therefore, the negative feedback control on β-carotene conversion through ISX appears as functional in the duodenum of GG but not of AA chickens. This could result in a higher availability of β-carotene in the duodenum of GG chickens, reducing the uptake of xanthophylls, liposoluble vitamins and cholesterol.
    Full-text · Article · Mar 2014 · The British journal of nutrition
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    Javad Nadaf · Cecile Berri · Ian Dunn · Estelle Godet · Elisabeth Le Bihan-Duval · Dirk-Jan de Koning
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    ABSTRACT: Genetical genomics has been suggested as a powerful approach to study the genotype-phenotype gap. However, the relatively low power of these experiments (usually related to the high cost) has hindered fulfilment of its promise, especially for loci (QTL) of moderate effects. One strategy to overcome the issue is to use a targeted approach. It has two clear advantages: (i) it reduces the problem to a simple comparison between different genotypic groups at the QTL and (ii) it is a good starting point to investigate downstream effects of the QTL. In the present study, from 698 F2 birds used for QTL mapping, gene expression profiles of 24 birds with divergent homozygous QTL genotypes were investigated. The targeted QTL was on chromosome 1 and affected initial pH of breast muscle. The biological mechanisms controlling this trait can be similar to those affecting malignant hyperthermia or muscle fatigue in human. The gene expression study identified ten strong local signals which were markedly more significant compared to any genes on the rest of the genome. The differentially expressed genes all mapped to a region < 1 Mb, suggesting a remarkable reduction of the QTL interval. These results combined with analysis of downstream effect of the QTL using gene network analysis suggest that the QTL is controlling pH by governing oxidative stress. The results were reproducible with using as few as 4 microarrays on pooled samples (with lower significance level). The results demonstrate that this cost effective approach is promising for characterization of QTL.
    Full-text · Article · Jan 2014 · Genetics
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    ABSTRACT: The social behavior of animals, which is partially controlled by genetics, is one of the factors involved in their adaptation to large breeding groups. To understand better the relationships between different social behaviors, fear behaviors and production traits, we analyzed the phenotypic and genetic correlations of these traits in Japanese quail by a second generation crossing of two lines divergently selected for their social reinstatement behavior. Analyses of results for 900 individuals showed that the phenotypic correlations between behavioral traits were low with the exception of significant correlations between sexual behavior and aggressive pecks both at phenotypic (0.51) and genetic (0.90) levels. Significant positive genetic correlations were observed between emotional reactivity toward a novel object and sexual (0.89) or aggressive (0.63) behaviors. The other genetic correlations were observed mainly between behavioral and production traits. Thus, the level of emotional reactivity, estimated by the duration of tonic immobility, was positively correlated with weight at 17 and 65 days of age (0.76 and 0.79, respectively) and with delayed egg laying onset (0.74). In contrast, a higher level of social reinstatement behavior was associated with an earlier egg laying onset (-0.71). In addition, a strong sexual motivation was correlated with an earlier laying onset (-0.68) and a higher number of eggs laid (0.82). A low level of emotional reactivity toward a novel object and also a higher aggressive behavior were genetically correlated with a higher number of eggs laid (0.61 and 0.58, respectively). These results bring new insights into the complex determinism of social and emotional reactivity behaviors in birds and their relationships with production traits. Furthermore, they highlight the need to combine animal welfare and production traits in selection programs by taking into account traits of sociability and emotional reactivity.
    Full-text · Article · Dec 2013 · PLoS ONE
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    ABSTRACT: For decades, genetic improvement based on measuring growth and body composition traits has been successfully applied in the production of meat-type chickens. However, this conventional approach is hindered by antagonistic genetic correlations between some traits and the high cost of measuring body composition traits. Marker-assisted selection should overcome these problems by selecting loci that have effects on either one trait only or on more than one trait but with a favorable genetic correlation. In the present study, identification of such loci was done by genotyping an F2 intercross between fat and lean lines divergently selected for abdominal fatness genotyped with a medium-density genetic map (120 microsatellites and 1302 single nucleotide polymorphisms). Genome scan linkage analyses were performed for growth (body weight at 1, 3, 5, and 7 weeks, and shank length and diameter at 9 weeks), body composition at 9 weeks (abdominal fat weight and percentage, breast muscle weight and percentage, and thigh weight and percentage), and for several physiological measurements at 7 weeks in the fasting state, i.e. body temperature and plasma levels of IGF-I, NEFA and glucose. Interval mapping analyses were performed with the QTLMap software, including single-trait analyses with single and multiple QTL on the same chromosome. Sixty-seven QTL were detected, most of which had never been described before. Of these 67 QTL, 47 were detected by single-QTL analyses and 20 by multiple-QTL analyses, which underlines the importance of using different statistical models. Close analysis of the genes located in the defined intervals identified several relevant functional candidates, such as ACACA for abdominal fatness, GHSR and GAS1 for breast muscle weight, DCRX and ASPSCR1 for plasma glucose content, and ChEBP for shank diameter. The medium-density genetic map enabled us to genotype new regions of the chicken genome (including micro-chromosomes) that influenced the traits investigated. With this marker density, confidence intervals were sufficiently small (14 cM on average) to search for candidate genes. Altogether, this new information provides a valuable starting point for the identification of causative genes responsible for important QTL controlling growth, body composition and metabolic traits in the broiler chicken.
    Full-text · Article · Sep 2013 · Genetics Selection Evolution

  • No preview · Article · Sep 2013
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    ABSTRACT: Session 25. Free communications - molecular genetics
    No preview · Conference Paper · Aug 2013
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    Full-text · Conference Paper · Aug 2013

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