References of "Gengler, Nicolas"
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See detailEquivalent mixed model for joint genetic evaluation considering molecular and phenotypic information
Gengler, Nicolas ULg; Colinet, Frédéric ULg

in Journal of Dairy Science (2009), 92(E-suppl.1), 315

Currently efforts are underway to introduce molecular information into genetic evaluation systems. A particular situation is genomic selection however simpler cases exists where major genes are known and ... [more ▼]

Currently efforts are underway to introduce molecular information into genetic evaluation systems. A particular situation is genomic selection however simpler cases exists where major genes are known and used by breeders. A new alternative strategy for the prediction of gene effects and especially their smooth integration into genetic evaluations based on an equivalent method was developed from existing theory. Underlying hypothesis were based on the idea that knowledge of genotypes will not affect overall additive genetic variance but only change expected values of genetic effects for animals with known genotypes. The developed equations were modified to allow that not all animals were genotyped. As the underlying mixed model is open a very large range of models can be used in situations including random regression models, multipletrait, maternal effects and multiple-across-country-evaluation models. Computations involved successive solving of two mixed models, with the use of an linear extrapolation to speed up convergence of gene effects. The method was tested for several known major genes and QTL, e.g. for the mh gene in the dual-purpose Belgian Blue population in Belgium. Modifications of the method could also be developed to be useful in the context of genomic selection. [less ▲]

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See detailMulti-trait animal model estimation of genetic parameters for linear type and gait traits in the Belgian warmblood horse
Rustin, M.; Janssens, S.; Buys, N. et al

in Journal of Animal Breeding & Genetics (2009), 126(5), 378--386

Summary Genetic parameters for the height at withers, 27 linear type and six linear gait traits were estimated for the Belgian warmblood horse. Observations on 987 mares, mostly 3 years old, were analysed ... [more ▼]

Summary Genetic parameters for the height at withers, 27 linear type and six linear gait traits were estimated for the Belgian warmblood horse. Observations on 987 mares, mostly 3 years old, were analysed using a multi-trait animal model. The statistical model included appraiser, age and location (date × place of appraisal) as fixed effects. Genetic parameters were estimated using a canonical transformation and an expectation-maximization restricted maximum likelihood algorithm with an additional deceleration step. Estimates of heritability for the 33 linear traits were between 0.15 and 0.55. Heritability of the height at withers was 0.34 ± 0.06. Estimated genetic correlations ranged from −0.60 to 0.98 with an average SE of 0.10. The highest positive correlations were found among traits of walk and among traits of trot. Volume and the quality of legs were the most negatively correlated. Estimated genetic parameters indicated that the linear scoring system is a valuable tool to assess conformation. The full (co)variance matrix is now available for breeding value estimation to support selection for conformation and gaits. [less ▲]

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See detailSystéme d'évaluation génétique pour les verrats Piétrain en croisement en Wallonie
Dufrasne, Marie ULg; Rustin, Maïté; Hammami, Hedi ULg et al

Computer development (2009)

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See detailDetection and Correction of Outliers for Fatty Acids Contents Measured by Mid-Infrared Spectrometry Using Random Regression Test-Day Models
Soyeurt, Hélène ULg; Dardenne, Pierre; Gengler, Nicolas ULg

in Book of Abstracts of the 60th Annual Meeting of the European Association for Animal Production (2009)

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See detailCombining microsatellite and pedigree data to estimate relationships among Skyros ponies.
Bömcke, Elisabeth ULg; Gengler, Nicolas ULg

in Journal of Applied Genetics (2009), 50(2), 133-43

Relationship coefficients are particularly useful to improve genetic management of endangered populations. These coefficients are traditionally based on pedigree data, but in case of incomplete or ... [more ▼]

Relationship coefficients are particularly useful to improve genetic management of endangered populations. These coefficients are traditionally based on pedigree data, but in case of incomplete or inexistent pedigrees they are replaced by coefficients calculated from molecular data. The main objective of this study was to develop a new method to estimate relationship coefficients by combining molecular with pedigree data, which is useful for specific situations where neither pedigree nor molecular data are complete. The developed method was applied to contribute to the conservation of the Skyros pony breed, which consists of less than 200 individuals, divided into 3 main herds or subpopulations. In this study, relationships between individuals were estimated using traditional estimators as well as the newly developed method. For this purpose, 99 Skyros ponies were genotyped at 16 microsatellite loci. It appeared that the limitation of the most common molecular-based estimators is the use of weights that assume relationships equal to 0. The results showed that, as a consequence of this limitation, negative relationship values can be obtained in small inbred populations, for example. By contrast, the combined estimator gave no negative values. Using principal component analysis, the combined estimator also enabled a better graphic differentiation between the 3 subpopulations defined previously. In conclusion, this new estimator can be a promising alternative to traditionally used estimators, especially in inbred populations, with both incomplete pedigree and molecular information. [less ▲]

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See detailGenetic variability of test-day stearoyl coenzyme-A desaturase 9 activity
Arnould, Valérie ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

in Journal of Dairy Science (2009), 92(E-suppl.1), 353-354

Milk fatty acid (FA) profile is far from the optimal fat composition in regards to human health. Different natural sources of variation such as feeding or genetics could be used to modify the contents of ... [more ▼]

Milk fatty acid (FA) profile is far from the optimal fat composition in regards to human health. Different natural sources of variation such as feeding or genetics could be used to modify the contents of unsaturated fatty acids. The impact of feeding is well described; however, genetics effects on the milk FA composition are not well studied. Increasing the unsaturated fatty acids contents of bovine milk could have the potential to raise the nutritive and therapeutic values of dairy products. The stearoyl Coenzyme-A desaturase 9 (delta-9) gene was identified as a potential functional candidate gene affecting milk fat composition in dairy cattle. The objective of this research was to study the genetic variability on this enzyme activity across lactations. A total of 199,977 test-day records were obtained from 29,603 Holstein cows in first lactation, 154,267 records from 23,453 Holstein cows in second lactation, and 173,244 records from 75,887 Holstein cows in third and later lactations. The used model was a multiple-trait random regressions test-day model. Fixed effects were: herd × date of test, and class of age. Random effects were: herd × year of calving, permanent environmental, additive genetic, and residual effects. The studied traits were milk yield, protein content, percentage of fat, monounsaturated fatty acids estimated by mid-infrared spectrometry, and the ratios reflecting the delta-9 activity. Obtained heritability estimates of delta-9 as well as the genetic and phenotypic correlations varied across lactations. These results suggest potential improvements of milk fat composition based on delta-9 activity using animal selection and appropriate management practices. [less ▲]

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See detailGenomic location of the bovine growth hormone secretagogue receptor (Ghsr) gene and investigation of genetic polymorphism
Colinet, Frédéric ULg; Vanderick, Sylvie ULg; Charloteaux, Benoît ULg et al

in Animal Biotechnology (2009), 20(1), 28-33

The growth hormone secretagogue receptor (GHSR) is involved in the regulation of energetic homeostasis and GH secretion. In this study, the bovine GHSR gene was mapped to BTA1 between BL26 and BMS4004 ... [more ▼]

The growth hormone secretagogue receptor (GHSR) is involved in the regulation of energetic homeostasis and GH secretion. In this study, the bovine GHSR gene was mapped to BTA1 between BL26 and BMS4004. Two different bovine GHSR CDS (GHSR1a and GHSR1b) were sequenced. Six polymorphisms (five SNPs and one 3-bp indel) were also identified, three of them leading to amino acid variations L24V, D194N, and Del R242. These variations are located in the extracellular N-terminal end, the exoloop 2, and the cytoloop 3 of the receptor, respectively. [less ▲]

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See detailGenetic analysis of lactoferrin content in bovine milk
Arnould, Valérie ULg; Soyeurt, Hélène ULg; Gengler, Nicolas ULg et al

in Journal of Dairy Science (2009), 92(5), 2151-2158

Bovine lactoferrin (LF) is mainly present in milk and shows important physiological and biological functions. The aim of this study was to estimate the heritability and correlation values of LF content in ... [more ▼]

Bovine lactoferrin (LF) is mainly present in milk and shows important physiological and biological functions. The aim of this study was to estimate the heritability and correlation values of LF content in bovine milk with different economic traits as milk yield (MY), fat and protein percentages, and somatic cell score (SCS). Variance components of the studied traits were estimated by REML using a multiple-trait mixed model. The obtained heritability (0.22) for LF content predicted using mid-infrared spectrometry (pLF) suggested the possibility of animal selection based on the increase of LF content in milk. The phenotypic and genetic correlation values calculated between pLF and SCS were moderate (0.31 and 0.24, respectively). Furthermore, a preliminary study of bovine LF gene polymorphism effects was performed on the same production traits. By PCR, all exons of the LF gene were amplified and then sequenced. Three new polymorphisms were detected in exon 2, exon 11, and intron 8. We examined the effects of LF gene polymorphisms of exons 2, 4, 9, 11, and 15, and intron 8 on pLF, MY, fat and protein percentages, and SCS. The different observed effects did not reach a significant level probably because of the characteristics of the studied population. However, the results were promising, and LF may be a potential indicator of mastitis. Further studies are necessary to evaluate the effect of genetic selection based on LF content on the improvement of mastitis resistance. [less ▲]

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See detailGenotype by environment interaction in dairy cattle
Hammami, Hedi ULg; Rekik, Boulbaba; Gengler, Nicolas ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2009), 13(1), 155-164

The aim of this literature review was to identify the existence and scope of genotype by environment interaction (G x E) from reports on dairy cattle populations in different management systems, Methods ... [more ▼]

The aim of this literature review was to identify the existence and scope of genotype by environment interaction (G x E) from reports on dairy cattle populations in different management systems, Methods applied to deal with G x E (controlled experiments and large data modeling) were discussed. A G x E was confirmed essentially when high differences between production environments and/or genotypes (genetically distant genotypes) were observed. Environmental effects were aggregated in most studies and identification of the components of the environment was largely unresolved, with only a few studies based on more definite-descriptors of environment. The implications of G x E on breeding decisions are discussed. Breeders should select genotypes on production traits within environmental conditions comparable to where candidate animals are intended to perform. [less ▲]

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See detailVariability of major fatty acid contents in Luxembourg dairy cattle
Soyeurt, Hélène ULg; Arnould, Valérie ULg; Dardenne, Pierre et al

in Book of Abstracts of the 60th Annual Meeting of the European Association for Animal Production (2009)

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See detailLe BCS, une méthode simple à la source de conseils variés : ration, repro et santé
Laloux, Laurent; Bastin, Catherine ULg; Gillon, Alain ULg et al

in 14ième Carrefour des Productions animales: Les filières bovines dans la tourmente, Produire plus et mieux avec moins: Gembloux, le 11 février 2009 (2009)

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See detailEstimates of genetic parameters among body condition score and fertility traits in first-parity Canadian cows
Bastin, Catherine ULg; Loker, Sarah; Gengler, Nicolas ULg et al

in Journal of Dairy Science (2009), 92 - E-Suppl 1

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See detailGenomische Selektion: ein Meilenstein auch in der Schweinezucht?
Buske, Bernd ULg; Gengler, Nicolas ULg

Article for general public (2009)

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See detailExpressing female fertility in the Walloon region of Belgium: how to do?
Vanderick, Sylvie ULg; Bastin, Catherine ULg; Gengler, Nicolas ULg

in Interbull Bulletin (2009), 40

Since September 2007, the Walloon Region of Belgium has used a genetic evaluation system for pregnancy rate in Holsteins and has participated in 3 of the 5 MACE trait INTERBULL runs for female fertility ... [more ▼]

Since September 2007, the Walloon Region of Belgium has used a genetic evaluation system for pregnancy rate in Holsteins and has participated in 3 of the 5 MACE trait INTERBULL runs for female fertility. In order to define general way of female fertility expression, a principal component analysis was carried out on six published foreign female fertility indexes. Results of were used to compute a direct female fertility index with the INTERBULL international female fertility proofs available on the Walloon scale. An indirect female fertility index was also developed in order to increase reliability of young bulls. Approximate procedure based on selection index was used to combine both indexes in an overall index called combined female fertility index. This index was highly correlated with the direct female fertility index (.96) and the first principal component (.85), therefore it was considered as good expression of female fertility. Moreover, this allowed recovering 4,019 INTERBULL bulls with a publishable female fertility index. [less ▲]

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See detailDéveloppement d’un outil de prédiction de la probabilité de réussite à l’insémination chez la vache laitière à partir des données du Contrôle Laitier
Laloux, Laurent; Bastin, Catherine ULg; Glorieux, Géry et al

in 15ème Rencontres Recherches Ruminants, Paris, les 3 et 4 décembre 2008 (2008, December)

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See detailAnalysis of the Skyros pony breed: population structure and genetic variability
Bömcke, Elisabeth ULg; Gengler, Nicolas ULg

Conference (2008, November)

Due to its geographic location, Greece is a crossroad between three continents and its mountainous landscape and numerous islands have lead to the creation of many small populations of distinct and ... [more ▼]

Due to its geographic location, Greece is a crossroad between three continents and its mountainous landscape and numerous islands have lead to the creation of many small populations of distinct and isolated breeds. On the basis of phenotypes and genotypes, seven native breeds were identified. The Skyros pony has a distinct phenotype from those of other breeds. This phenotypic difference seems to be linked to the fact that the Skyros pony is less genetically similar to the other Greek breed than the other breeds are to each other as shown in previous studies. Furthermore, the Skyros pony breed risk status is described as endangered according to the criteria of the Food and Agricultural Organization (DAD-IS). The main reason is that the population is concentrated only in three herds of reduced size. This study analyses the population structure and describes the genetic variability of the breed using 15 microsatellite markers and available genealogical information. The molecular characterization and the pedigree were also used to investigate the presence of bottleneck. Factorial correspondence analysis and analysis of molecular variance showed that the three herds seemed to be genetically distinct even if the genetic variance between herds was low (5.75%). For the whole population, the mean total number of allele per locus was 5.93. The average Polymorphism Information Content value was relatively high (~ 0.60) as the observed heterozygosity (0.64) and the expected heterozygosity (0.62). The comparison with other studies showed that these values were well within the range for domestic horses but were at the lower end of that range, i.e. with the values from breeds with small population size or recent bottlenecks. However, these values indicated a still substantial genetic diversity in the Skyros breed that could be useful for planning future breeding strategies for the breed conservation. This is consistent with the results of various bottleneck tests, which detected no evidence of bottleneck when considering the whole population but suggested that there was bottleneck in two of the three main herds of Skyros pony. Comparisons between DNA-based and pedigree-based results showed that the loss of genetic diversity has probably occurred before the beginning of breed registration. [less ▲]

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See detailGenetic parameters of saturated and monounsaturated fatty acid content and the ratio of saturated to unsaturated fatty acids in bovine milk.
Soyeurt, Hélène ULg; Dardenne, Pierre; Dehareng, Frédéric et al

in Journal of Dairy Science (2008), 91(9), 3611-26

Fatty acid composition influences the nutritional quality of milk and the technological properties of butter. Using a prediction of fatty acid (FA) contents by mid-infrared (MIR) spectrometry, a large ... [more ▼]

Fatty acid composition influences the nutritional quality of milk and the technological properties of butter. Using a prediction of fatty acid (FA) contents by mid-infrared (MIR) spectrometry, a large amount of data concerning the FA profile in bovine milk was collected. The large number of records permitted consideration of more complex models than those used in previous studies. The aim of the current study was to estimate the effects of season and stage of lactation as well as genetic parameters of saturated (SAT) and monounsaturated (MONO) fatty acid contents in bovine milk and milk fat, and the ratio of SAT to unsaturated fatty acids (UNSAT) that reflect the hardness of butter (SAT:UNSAT), using 7 multiple-trait, random-regression test-day models. The relationship between these FA traits with common production traits was also studied. The data set contained 100,841 test-day records of 11,626 Holstein primiparous cows. The seasonal effect was studied based on unadjusted means. These results confirmed that milk fat produced during spring and summer had greater UNSAT content compared with winter (63.13 vs. 68.94% of SAT in fat, on average). The effect of stage of lactation on FA profile was studied using the same methodology. Holstein cows in early first lactation produced a lower content of SAT in their milk fat. Variance components were estimated using a Bayesian method via Gibbs sampling. Heritability of SAT in milk (0.42) was greater than heritability of SAT in milk fat (0.24). Estimates of heritability for MONO were also different in milk and fat (0.14 vs. 0.27). Heritability of SAT:UNSAT was moderate (0.27). For all of these traits, the heritability estimates and the genetic and phenotypic correlations varied through the lactation. [less ▲]

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