Publications

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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.
    Genetics Selection Evolution 04/2014; 46(1):25. · 2.86 Impact Factor
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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.
    The British journal of nutrition 03/2014; · 3.45 Impact Factor
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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.
    Genetics 01/2014; · 4.39 Impact Factor
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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.
    Genetics Selection Evolution 09/2013; 45(1):36. · 2.86 Impact Factor
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    ABSTRACT: This descriptive study of the abdominal fat transcriptome takes advantage of two experimental lines of meat-type chickens (Gallus domesticus), which were selected over seven generations for a large difference in abdominal (visceral) fatness. At the age of selection (9 wk), the fat line (FL) and lean line (LL) chickens exhibit a 2.5-fold difference in abdominal fat weight, while their feed intake and body weight are similar. These unique avian models were originally created to unravel genetic and endocrine regulation of adiposity and lipogenesis in meat-type chickens. The Del-Mar 14K Chicken Integrated Systems microarray was used for a time-course analysis of gene expression in abdominal fat of FL and LL chickens during juvenile development (1--11 weeks of age). Microarray analysis of abdominal fat in FL and LL chickens revealed 131 differentially expressed (DE) genes (FDR<=0.05) as the main effect of genotype, 254 DE genes as an interaction of age and genotype and 3,195 DE genes (FDR<=0.01) as the main effect of age. The most notable discoveries in the abdominal fat transcriptome were higher expression of many genes involved in blood coagulation in the LL and up-regulation of numerous adipogenic and lipogenic genes in FL chickens. Many of these DE genes belong to pathways controlling the synthesis, metabolism and transport of lipids or endocrine signaling pathways activated by adipokines, retinoid and thyroid hormones. The present study provides a dynamic view of differential gene transcription in abdominal fat of chickens genetically selected for fatness (FL) or leanness (LL). Remarkably, the LL chickens over-express a large number of hemostatic genes that could be involved in proteolytic processing of adipokines and endocrine factors, which contribute to their higher lipolysis and export of stored lipids. Some of these changes are already present at 1 week of age before the divergence in fatness. In contrast, the FL chickens have enhanced expression of numerous lipogenic genes mainly after onset of divergence, presumably directed by multiple transcription factors. This transcriptional analysis shows that abdominal fat of the chicken serves a dual function as both an endocrine organ and an active metabolic tissue, which could play a more significant role in lipogenesis than previously thought.
    BMC Genomics 08/2013; 14(1):557. · 4.40 Impact Factor
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    ABSTRACT: Improving feed efficiency remains crucial for poultry production. Birds have previously been selected on their ability to digest their diet, as assessed by AMEn (Apparent Metabolisable Energy corrected for zero nitrogen). Such selection, for either a high (D+) or a low AMEn (D-), affects energy, nitrogen, lipid and starch digestibility. The aim of this study was to establish whether selection on the digestive ability of birds modified metabolic traits. A total of 630 broiler chickens of the eighth generation of a divergent selection experiment on AMEn were used for this purpose. A balance trial was performed to determine energy, nitrogen and phosphorus retention. Growth performance was recorded and body protein and lipid deposition assessed by breast and abdominal fat yields. Tibia development and mineralisation were also studied and heat production was indirectly assessed through the measurement of body temperature during fasting and feeding. Phenotypic correlations estimated within line showed that an increased efficiency was associated to fatter birds and more solid bones in D- but not in D+ line, whereas increased consumption was associated with more solid bones in D+ but not in D- line. The heritability estimates for metabolic traits were relatively high, except for temperature traits (from 0.08 to 0.12), ranging from 0.28 to 0.56 for body composition, and from 0.38 to 0.77 for bone characteristics. Breast meat yield did not differ between the two lines whereas a slight increase in abdominal fat yield was observed in the high-digestion line (D+). The relative dry tibia weights and ash weights were higher in D+ birds (+6.56 and +8.06%, respectively) but the lengths and the diameters of the tibia were lower (-7.89 and -3.77%, respectively). Finally, AMEn was poorly correlated with almost all metabolic traits (ranging from -0.10 to 0.20), indicating that the ability of the animal to digest its diet is genetically independent of post-digestion metabolic traits.
    Journal of Animal Science 03/2013; · 2.09 Impact Factor
  • E Baéza, E Le Bihan-Duval
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    ABSTRACT: Divergent selection of chickens for low or high abdominal fat (AF) but similar BW at 63 days of age was undertaken in 1977. The selection programme was conducted over seven successive generations. The difference between lines was then maintained constant at about twice the AF in the fat line as in the lean line. The aims of the first studies on these divergent chicken lines were to describe the growth, body composition and reproductive performance in young and adult birds. The lines were then used to improve the understanding of the relationship between fatness and energy and protein metabolism in the liver, muscle and adipose tissues, as well as the regulation of such metabolism at hormonal, gene and hypothalamic levels. The effects on muscle energy metabolism in relation to meat quality parameters were also described. This paper reviews the main results obtained with these lines.
    animal 02/2013; · 1.65 Impact Factor
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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.
    PLoS ONE 01/2013; 8(12):e82157. · 3.73 Impact Factor
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    ABSTRACT: Improving the sustainability of poultry production involves limiting its environmental impact while maintaining effectiveness. It has recently been shown that genetic selection on the ability of chickens to digest wheat at 23 days of age can decrease chicken excretion without decreasing body weight (BW) at this age. The aim of this study was to check whether selection on digestibility modified excretion and growth performance over the whole production cycle. The two divergent lines selected for high (D+) and low (D-) AMEn (apparent metabolizable energy corrected for zero nitrogen balance) values were compared with a reference line used at the beginning of the selection experiment (RL), to evaluate the potential excretion improvement that could be expected with such selection. These 3 lines were therefore compared for growth and excretion (raw and relative to feed intake fresh and dry excreta weights, and moisture content of excreta) from 4 to 53 d. Between 4 and 7 d, 17 and 21 d and between 49 and 53 d, AMEn, nitrogen and phosphorus excretion rates were also compared between the 3 lines. Furthermore, body composition (breast meat and abdominal fat yields), bone breaking strength and meat quality traits (lightness, redness, yellowness and ultimate pH) were compared between lines at 53 d.Over the whole rearing period, D+ birds excreted significantly less fresh and dry excreta (-56 and -61%) than D- and RL birds (-6 and -26%). Similarly, nitrogen and phosphorus excretion rates of D+ birds were 13 to 30% lower than those of D- birds and 12 to 19% lower than RL birds, depending on age. These excretion differences may be related to the differential development of the gastro-intestinal tract. Differences between lines were already present at 7 d for relative gizzard weight and the weight of the upper to the lower part of the gastro-intestinal tract ratio. Anatomic differences were maximum at 23 d for all traits except for relative weight of the duodenum. At slaughter age, BW, breast and fat yields, and meat colour did not differ between D+ and RL birds, but D- birds were fatter than D+ and RL birds. Finally, ultimate meat pH was 1 to 2% higher in RL birds than in the D+ and D- lines.In conclusion, this study showed that selection of chickens on AMEn is a possible way to reduce the environmental impact of production over the whole rearing period without negative impact on growth, body composition or meat quality.
    Journal of Animal Science 12/2012; · 2.09 Impact Factor
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    ABSTRACT: A polymorphism in the promoter of the β,β-carotene 15,15'-monooxygenase 1 (BCMO1) gene recently was identified in an experimental cross between 2 chicken lines divergently selected on growth rate and found to be associated with variations in the yellow color of the breast meat. In this study, the effects of the polymorphism on several aspects of carotenoid metabolism were evaluated in chickens sharing the same genetic background except for their genotype at the BCMO1 locus. We confirmed that BCMO1 mRNA levels varied (P < 0.001) between the 2 homozygous genotypes (GG < AA) and in the Pectoralis major muscle. By contrast, BCMO1 mRNA expression was not affected (P > 0.05) by the polymorphism in the duodenum, liver, or Sartorius muscle. The breast meat of GG chickens was more (P < 0.001) yellow and richer in lutein (P < 0.01) and zeaxanthin (P < 0.05) compared to that of AA chickens, whereas these parameters did not differ (P > 0.05) in the other tissues tested. The GG were also characterized by lower (P < 0.01) plasma lutein and zeaxanthin levels than AA without affecting plasma and tissue levels of fat-soluble vitamins A and E. As lutein and zeaxanthin are usually not considered as substrates of the BCMO1 enzyme, the impact of BCMO1 polymorphism on the activity of other genes involved in carotenoid transport (SCARB1 and CD36 encoding the scavenger receptor class B type I and the cluster determinant 36, respectively) and metabolism (BCDO2 encoding β,β-carotene 9',10'-dioxygenase 2) was evaluated. The BCMO1 polymorphism did not affect mRNA levels of BCDO2, SCARB1, or CD36, regardless of tissue considered. Taken together, these results indicated that a genetic variant of BCMO1 specifically changes lutein and zeaxanthin content in the chicken plasma and breast muscle, without impairing vitamin A and E metabolism.
    Journal of Animal Science 11/2012; · 2.09 Impact Factor
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    ABSTRACT: BACKGROUND: Slow-growing lines are widely used in France for the production of high quality free-range chickens. While such production is mainly dedicated to the whole carcass market, new prospects are opening up for the development of cuts and processed products. Whether the body composition and meat quality of slow-growing birds can be improved by selection has thus become an important issue. The genetic parameters of growth, body composition and breast meat quality traits were evaluated in relation to behaviour at slaughter in a large pedigree population including 1022 male and female slow-growing birds. RESULTS: The heritability coefficients (h2) of body weight and body composition traits varied from 0.3 to 0.5. Abdominal fat percentage was genetically positively correlated with body weight but negatively correlated with breast muscle yield. The characteristics of the breast meat (i.e., post-mortem fall in pH, colour, drip loss, shear-force and lipid content) were all heritable, with h2 estimates ranging from 0.18 to 0.48. The rate and extent of the fall in pH were under different genetic control. Strong negative genetic correlations were found between the ultimate pH and the lightness, yellowness and drip loss of the meat. Wing flapping on the shackle line was significantly heritable and exhibited marked genetic correlations with the pH at 15 min post-slaughter and the redness of the meat. The genetic relationships between meat quality traits, body weight and body composition appeared slightly different between males and females. CONCLUSION: This study suggested that there are a number of important criteria for selection on carcass and breast meat quality in slow-growing birds. Selection for reduced abdominal fatness and increased breast muscle yield should be effective as both traits were found to be highly heritable and favourably correlated. Substantial improvement in meat quality could be achieved by selection on ultimate pH which was highly heritable and strongly correlated with the colour and water-holding capacity of the meat. Moreover, this study revealed for the first time that the behaviour at slaughter is partly genetically determined in the chicken.
    BMC Genetics 10/2012; 13(1):90. · 2.81 Impact Factor
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    ABSTRACT: The aim of the study was to evaluate the impact of 2 isoenergetic growing diets with different CP (17 vs. 23%) on the performance and breast meat quality of 2 lines of chicken divergently selected for abdominal fatness [i.e., fat and lean (LL) lines]. Growth performance, breast and abdominal fat yields, breast meat quality parameters (pH, color, drip loss), and muscle glycogen storage at death were measured. Increased dietary CP resulted in increased BW, increased breast meat yield, and reduced abdominal fatness at slaughter regardless of genotype (P < 0.001). By contrast, dietary CP affected glycogen storage and the related meat quality parameters only in the LL chickens. Giving LL chickens the low-CP diet led to reduced concentration of muscle glycogen (P < 0.01), and as a result, breast meat with a higher (P < 0.001) ultimate pH, decreased (P < 0.001) lightness, and reduced (P < 0.001) drip loss during storage. The decreased muscle glycogen content observed in LL receiving the low-CP diet compared with the high-CP diet occurred concomitantly with greater phosphorylation amount for the α-catalytic subunit of adenosine monophosphate-activated protein kinase and glycogen synthase. This was consistent with the reduced muscle glycogen content observed in LL fed the low-CP diet because adenosine monophosphate-activated protein kinase inhibits glycogen synthesis through its action on glycogen synthase. Our results demonstrated that nutrition is an effective means of modulating breast meat properties in the chicken. The results also highlighted the need to take into account interaction with the genetic background of the animal to select nutritional strategies to improve meat quality traits in poultry.
    Journal of Animal Science 02/2012; 90(2):447-55. · 2.09 Impact Factor
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    ABSTRACT: Because of the increasing demand for raw cuts and processed products, there is a trend to producing very heavy broilers. Breeds that are used for such kinds of production have been intensively selected for growth rate and breast meat yield, and birds are reared for a longer period than standard broilers. This study was to evaluate the effects of increasing slaughter age on technical and economic factors, including production efficiency and environmental costs, bird welfare, and breast meat quality in a modern heavy broiler line. Five groups of 300 male Ross 708 chickens were reared until slaughter ages of 35, 42, 49, 56, or 63 d. Increasing age at slaughter from 35 to 63 d resulted in a 7.4-fold increase (P < 0.01) in mortality rate (5.21 vs. 0.70%). It also increased (P < 0.001) the slaughter weight and ADFI of birds 2.5- and 1.4-fold, respectively, without affecting their G:F. Under our experimental conditions, economic profit evaluated through the net gain reached a maximum at 42 d. The moisture and ammonium content of litter increased (P < 0.05 and P < 0.01, respectively) rapidly during rearing concomitantly with increased (P < 0.05) occurrence and severity of contact dermatitis and decreased (P < 0.05) walking ability and activity of birds. Thermal comfort also decreased (P < 0.05) greatly as early as 42 d of age. Changes in carcass quality occurred mainly between 35 and 56 d of age, with a progressive increase (P < 0.001) in breast and leg yield, whereas body fatness was barely affected by age. Major changes in breast meat traits were observed between 35 and 49 d of age, with an increase in muscle pH at 15 min (P < 0.01) and 24 h (P < 0.001) postmortem and reduced (P < 0.001) lightness and drip loss. The protein and lipid content of raw breast meat also increased (P < 0.05 and P < 0.01, respectively) with age. Taking into account the main aspects of sustainability, we could recommend slaughtering chickens of heavy line at 42 d of age.
    Journal of Animal Science 12/2011; 90(6):2003-13. · 2.09 Impact Factor
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    ABSTRACT: Poultry production has been widely criticized for its negative environmental impact related to the quantity of manure produced and to its nitrogen and phosphorus content. In this study, we investigated which traits related to excretion could be used to select chickens for lower environmental pollution.The genetic parameters of several excretion traits were estimated on 630 chickens originating from 2 chicken lines divergently selected on apparent metabolisable energy corrected for zero nitrogen (AMEn) at constant body weight. The quantity of excreta relative to feed consumption (CDUDM), the nitrogen and phosphorus excreted, the nitrogen to phosphorus ratio and the water content of excreta were measured, and the consequences of such selection on performance and gastro-intestinal tract (GIT) characteristics estimated. The genetic correlations between excretion, GIT and performance traits were established. Heritability estimates were high for CDUDM and the nitrogen excretion rate (0.30 and 0.29, respectively). The other excretion measurements showed low to moderate heritability estimates, ranging from 0.10 for excreta water content to 0.22 for the phosphorus excretion rate. Except for the excreta water content, the CDUDM was highly correlated with the excretion traits, ranging from -0.64 to -1.00. The genetic correlations between AMEn or CDUDM and the GIT characteristics were very similar and showed that a decrease in chicken excretion involves an increase in weight of the upper part of the GIT, and a decrease in the weight of the small intestine. In order to limit the environmental impact of chicken production, AMEn and CDUDM seem to be more suitable criteria to include in selection schemes than feed efficiency traits.
    BMC Genetics 08/2011; 12:71. · 2.81 Impact Factor
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    ABSTRACT: The processing ability of poultry meat is highly related to its ultimate pH, the latter being mainly determined by the amount of glycogen in the muscle at death. The genetic determinism of glycogen and related meat quality traits has been established in the chicken but the molecular mechanisms involved in variations in these traits remain to be fully described. In this study, Chicken Genome Arrays (20 K) were used to compare muscle gene expression profiles of chickens from Fat (F) and Lean (L) lines that exhibited high and low muscle glycogen content, respectively, and of individuals exhibiting extremely high (G+) or low (G-) muscle glycogen content originating from the F2 cross between the Fat and Lean lines. Real-time RT-PCR was subsequently performed to validate the differential expression of genes either selected from the microarray analysis or whose function in regulating glycogen metabolism was well known. Among the genes found to be expressed in chicken P. major muscle, 197 and 254 transcripts appeared to be differentially expressed on microarrays for the F vs. L and the G+ vs. G- comparisons, respectively. Some involved particularly in lipid and carbohydrate metabolism were selected for further validation studies by real-time RT-PCR. We confirmed that, as in mammals, the down-regulation of CEBPB and RGS2 coincides with a decrease in peripheral adiposity in the chicken, but these genes are also suggested to affect muscle glycogen turnover through their role in the cAMP-dependent signalling pathway. Several other genes were suggested to have roles in the regulation of glycogen storage in chicken muscle. PDK4 may act as a glycogen sensor in muscle, UGDH may compete for glycogen synthesis by using UDP-glucose for glucoronidation, and PRKAB1, PRKAG2, and PHKD may impact on glycogen turnover in muscle, through AMP-activated signalling pathways. This study is the first stage in the understanding of molecular mechanisms underlying variations in poultry meat quality. Large scale analyses are now required to validate the role of the genes identified and ultimately to find molecular markers that can be used for selection or to optimize rearing practices.
    BMC Genomics 02/2011; 12:112. · 4.40 Impact Factor
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    ABSTRACT: Feed costs represent about 70% of the costs of raising broilers. The main way to decrease these costs is to improve feed efficiency by modification of diet formulation, but one other possibility would be to use genetic selection. Understanding the genetic architecture of the gastro-intestinal tract (GIT) and the impact of the selection criterion on the GIT would be of particular interest. We therefore studied the genetic parameters of AMEn (Apparent metabolisable energy corrected for zero nitrogen balance), feed efficiency, and GIT traits in chickens.Genetic parameters were estimated for 630 broiler chickens of the eighth generation of a divergent selection experiment on AMEn. Birds were reared until 23 d of age and fed a wheat-based diet. The traits measured were body weight (BW), feed conversion ratio (FCR), AMEn, weights of crop, liver, gizzard and proventriculus, and weight, length and density of the duodenum, jejunum and ileum. The heritability estimates of BW, FCR and AMEn were moderate. The heritability estimates were higher for the GIT characteristics except for the weights of the proventriculus and liver. Gizzard weight was negatively correlated with density (weight to length ratio) of duodenum, jejunum and ileum. Proventriculus and gizzard weights were more strongly correlated with AMEn than with FCR, which was not the case for intestine weight and density. GIT traits were largely dependent on genetics and that selecting on AMEn or FCR would modify them. Phenotypic observations carried out in the divergent lines selected on AMEn were consistent with estimated genetic correlations between AMEn and GIT traits.
    BMC Genetics 01/2011; 12:59. · 2.81 Impact Factor
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    ABSTRACT: Classical quantitative trait loci (QTL) analysis and gene expression QTL (eQTL) were combined to identify the causal gene (or QTG) underlying a highly significant QTL controlling the variation of breast meat color in a F2 cross between divergent high-growth (HG) and low-growth (LG) chicken lines. Within this meat quality QTL, BCMO1 (Accession number GenBank: AJ271386), encoding the β-carotene 15, 15'-monooxygenase, a key enzyme in the conversion of β-carotene into colorless retinal, was a good functional candidate. Analysis of the abundance of BCMO1 mRNA in breast muscle of the HG x LG F2 population allowed for the identification of a strong cis eQTL. Moreover, reevaluation of the color QTL taking BCMO1 mRNA levels as a covariate indicated that BCMO1 mRNA levels entirely explained the variations in meat color. Two fully-linked single nucleotide polymorphisms (SNP) located within the proximal promoter of BCMO1 gene were identified. Haplotype substitution resulted in a marked difference in BCMO1 promoter activity in vitro. The association study in the F2 population revealed a three-fold difference in BCMO1 expression leading to a difference of 1 standard deviation in yellow color between the homozygous birds at this haplotype. This difference in meat yellow color was fully consistent with the difference in carotenoid content (i.e. lutein and zeaxanthin) evidenced between the two alternative haplotypes. A significant association between the haplotype, the level of BCMO1 expression and the yellow color of the meat was also recovered in an unrelated commercial broiler population. The mutation could be of economic importance for poultry production by making possible a gene-assisted selection for color, a determining aspect of meat quality. Moreover, this natural genetic diversity constitutes a new model for the study of β-carotene metabolism which may act upon diverse biological processes as precursor of the vitamin A.
    PLoS ONE 01/2011; 6(7):e14825. · 3.73 Impact Factor
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    ABSTRACT: [This corrects the article on p. e14825 in vol. 6.].
    PLoS ONE 01/2011; 6(9). · 3.73 Impact Factor
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    ABSTRACT: Two lines of broilers divergently selected for a high (D+) or a low (D-) AME(n) on a wheat-based diet were studied for morphological and histological characteristics of the digestive tract. A total of 630 birds of both lines were slaughtered after a 23-d feeding period. Digestive tract morphology and intestinal histology were investigated on a total of 24 birds to describe the consequences of divergent selection. Birds of the D+ line had 34% heavier gizzards (P < 0.001) and 22% heavier proventriculi than their D- counterparts. In contrast, intestines were 15 to 40% heavier in D- birds, mainly in the jejunum (P < 0.001) and ileum (P < 0.001). Intestinal segments were also longer (between 3 and 6%) in the D- birds. Intestinal villi were larger and longer in D- birds (P < 0.001), mainly in the jejunum (14 to 16%), and crypts were 10 to 15% deeper for the 3 intestinal segments in D- birds (P < 0.001). Muscle layers of the intestine were 17 to 24% thicker (P < 0.001) and goblet cells were 27 to 34% more numerous in the jejunum and ileum of D- birds (P = 0.027). This new characterization of the 2 lines shows that divergent selection based on AME(n) modified the morphology of the proventriculus and gizzard, suggesting greater activity of this compartment in D+ than in D- birds. Intestinal adaptation revealed by visceral organ weight and length and histological modifications in D- birds can be viewed as an attempt to compensate for the low functionality of the gastric area.
    Poultry Science 09/2010; 89(9):1955-61. · 1.52 Impact Factor

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