References of "Gengler, Nicolas"
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See detailGenetic selection: Evaluation and methods
Wiggans, George R.; Gengler, Nicolas ULg

in Fuquay, J. W.; Fox, P. F.; McSweeney, P. L. H. (Eds.) Encyclopedia of Dairy Sciences (2011)

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See detailGenetic variability in the Skyros pony and its relationship with other Greek and foreign horse breeds
Bömcke, Elisabeth ULg; Gengler, Nicolas ULg; Cothran, E Gus

in Genetics and Molecular Biology (2011), 34

In Greece, seven native horse breeds have been identified so far. Among these, the Skyros pony is outstanding through having a distinct phenotype. In the present study, the aim was to assess genetic ... [more ▼]

In Greece, seven native horse breeds have been identified so far. Among these, the Skyros pony is outstanding through having a distinct phenotype. In the present study, the aim was to assess genetic diversity in this breed, by using different types of genetic loci and available genealogical information. Its relationships with the other Greek, as well as foreign, domestic breeds were also investigated. Through microsatellite and pedigree analysis it appeared that the Skyros presented a similar level of genetic diversity to the other European breeds. Nevertheless, comparisons between DNA-based and pedigree-based results revealed that a loss of genetic diversity had probably already occurred before the beginning of breed registration. Tests indicated the possible existence of a recent bottleneck in two of the three main herds of Skyros pony. Nonetheless, relatively high levels of heterozygosity and Polymorphism Information Content indicated sufficient residual genetic variability, probably useful in planning future strategies for breed conservation. Three other Greek breeds were also analyzed. A comparison of these with domestic breeds elsewhere, revealed the closest relationships to be with the Middle Eastern types, whereas the Skyros itself remained isolated, without any close relationship, whatsoever. [less ▲]

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See detailEstimating myostatin gene effect on milk performance traits using estimated gene content for a large number of non-genotyped cows
Buske, Bernd ULg; Szydlowski, Maciej; Verkenne, Catherine et al

in Animal (2011), 5(1), 43-47

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See detailLes élevages Bleue Mixte et leur rentabilité au travers du projet franco-belge BlueSel
Glorieux, Géry; Beguin, E.; Desert Gouwy, H. et al

in 17ièmes Rencontres Recherches Ruminants, Paris, les 8 et 9 Décembre 2010 (2010, December)

La « Bleue Mixte » (BM) est une race à petit effectif localisée de part et d’autre de la frontière franco-belge. Menacée de disparition, elle bénéficie d’un projet transfrontalier BlueSel soutenu par le ... [more ▼]

La « Bleue Mixte » (BM) est une race à petit effectif localisée de part et d’autre de la frontière franco-belge. Menacée de disparition, elle bénéficie d’un projet transfrontalier BlueSel soutenu par le programme européen INTERREG IV et les autorités françaises et wallonnes. L’objectif de ce projet est d’assurer la conservation, la sélection et la promotion de la BM. L’un des volets du programme consiste à étudier la rentabilité économique des troupeaux BM. Il s’appuie sur un réseau de 16 fermes de référence mis en place fin 2008. La collecte des résultats repose sur la méthodologie mise en oeuvre au sein du dispositif français des Réseaux d’élevage. Les exploitations BM sont regroupées selon deux systèmes, herbivore et polyculture-élevage, et comparées aux exploitations laitières Prim’Holstein (PH) du Réseau d’élevage de Nord-Picardie. Les premiers résultats démontrent la capacité des éleveurs de vaches BM à obtenir de bonnes performances économiques malgré une faible productivité laitière (4200 l/VL/an) et un moindre prix du lait. En système herbivore, les exploitations BM s’avèrent économes et autonomes avec une excellente valorisation des prairies. En système de polyculture-élevage, les troupeaux sont conduits de façon à peine plus intensive qu’en système herbivore contrairement aux troupeaux PH. L’étude du fonctionnement des troupeaux BM va se poursuivre dans le cadre du projet BlueSel pour approfondir les logiques de fonctionnement très spécifiques de ces troupeaux et pour mesurer l’impact de la race sur les temps de travaux. [less ▲]

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See detailAdding value to test-day data by using modified best prediction method
Gillon, Alain ULg; Abras, Sven; Mayeres, Patrick et al

in ICAR Technical Series (2010, November), 14

Computation of lactation yields from test-day data has lost much of its importance for genetic evaluations as the use of test-day models is currently quite widespread. In the other hand its interest for ... [more ▼]

Computation of lactation yields from test-day data has lost much of its importance for genetic evaluations as the use of test-day models is currently quite widespread. In the other hand its interest for intra-farm management is increasing as a base for advanced management tools. The first and principal aim of this study was to develop a method which takes into account advantages and disadvantages of existing methods, and to test its potential to provide useful management tools to dairy farmers. A test-day model with modifications to able daily run and management tools was developed. Because of its similarities with best prediction, the method developed here was called modified best prediction. The second objective was to compare the accuracy of this new method with best prediction and test interval methods. Modified best prediction showed good results for predicting daily yields and was slightly better than best prediction for lactation yields prediction. Management tools obtained with modified best prediction are explained. [less ▲]

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See detailShort communication: Genetic variation of saturated fatty acids in Holsteins in the Walloon region of Belgium
Arnould, Valérie ULg; Hammami, Hedi ULg; Soyeurt, Hélène ULg et al

in Journal of Dairy Science (2010), 93

Random regression test-day models using Legendre polynomials are commonly used for the estimation of genetic parameters and genetic evaluation for test-day milk production traits. However, some ... [more ▼]

Random regression test-day models using Legendre polynomials are commonly used for the estimation of genetic parameters and genetic evaluation for test-day milk production traits. However, some researchers have reported that these models present some undesirable properties such as the overestimation of variances at the edges of lactation. Describing genetic variation of saturated fatty acids expressed in milk fat might require the testing of different models. Therefore, 3 different functions were used and compared to take into account the lactation curve: (1) Legendre polynomials with the same order as currently applied for genetic model for production traits; 2) linear splines with 10 knots; and 3) linear splines with the same 10 knots reduced to 3 parameters. The criteria used were Akaike’s information and Bayesian information criteria, percentage square biases, and log-likelihood function. These criteria indentified Legendre polynomials and linear splines with 10 knots reduced to 3 parameters models as the most useful. Reducing more complex models using eigenvalues seemed appealing because the resulting models are less time demanding and can reduce convergence difficulties, because convergence properties also seemed to be improved. Finally, the results showed that the reduced spline model was very similar to the Legendre polynomials model. [less ▲]

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See detailGenetic parameters of mastitis-correlated milk components in first parity dairy cows
Gillon, Alain ULg; Bastin, Catherine ULg; Soyeurt, Hélène ULg et al

Conference (2010, August 06)

Ind. of lactoferrin content, ind. of Na content, and lactose content were the three most correlated milk components with somatic cell score among available milk components predicted by mid-infrared ... [more ▼]

Ind. of lactoferrin content, ind. of Na content, and lactose content were the three most correlated milk components with somatic cell score among available milk components predicted by mid-infrared spectrometry on 590,083 test-day records from Walloon Region of Belgium collected between 2007 and 2009. Mean daily heritabilities and mean genetic correlations of these four traits were estimated using Gibbs sampling methodology applied to a multi-trait random regression test-day model with a subset of these records. Mean daily heritabilities of ind. lactoferrin content (0.34), ind. Na content (0.37) and lactose content (0.42) were higher then SCS (0.16) and mean genetic correlations were moderate (from -0.18 to -0.73), showing that these traits could be used together to describe udder health in genetic evaluations instead of SCS alone when clinical mastitis data are not available. [less ▲]

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See detailEstimation of Genetic Parameters for Test Day Milk Yields of Moroccan Holstein Cows Using Random Regression Test Day Model
Tijani, Aziz; Rgayai, Brahim; Hammami, Hedi ULg et al

Poster (2010, August 02)

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See detailEstimation of Genetic Parameters for Test Day Milk Yields of Moroccan Holstein Cows Using Random Regression Test Day Model
Tijani, Aziz; Rgayai, Brahim; Hammami, Hedi ULg et al

in Proceedings of the 9th World Congress on Genetics Applied to Livestock Production (2010, August)

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See detailGenetic correlations among body condition score, yield and fertility in multiparous cows using random regression models
Bastin, Catherine ULg; Gillon, Alain ULg; Massart, Xavier et al

in Proceedings of the 9th World Congress on Genetics Applied to Livestock Production (2010, August)

Genetic correlations between body condition score (BCS) in lactation 1 to 3 and four economically important traits (days open, 305-days milk, fat, and protein yields recorded in the first 3 lactations ... [more ▼]

Genetic correlations between body condition score (BCS) in lactation 1 to 3 and four economically important traits (days open, 305-days milk, fat, and protein yields recorded in the first 3 lactations) were estimated on about 12,500 Walloon Holstein cows using 4-trait random regression models. Results indicated moderate favorable genetic correlations between BCS and days open (from -0.46 to -0.62) and suggested the use of BCS for indirect selection on fertility. However, unfavorable genetic correlations between BCS and yields (from -0.16 to -0.71) indicated that selection on BCS would have deleterious effects on milk, fat, and protein yields, especially in lactation greater than 1. [less ▲]

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See detailGenetic parameters of mastitis-correlated milk components in first parity dairy cows
Gillon, Alain ULg; Bastin, Catherine ULg; Soyeurt, Hélène ULg et al

in Proceedings of the 9th World Congress on Genetics Applied to Livestock Production (2010, August)

Ind. of lactoferrin content, ind. of Na content, and lactose content were the three most correlated milk components with somatic cell score among available milk components predicted by mid-infrared ... [more ▼]

Ind. of lactoferrin content, ind. of Na content, and lactose content were the three most correlated milk components with somatic cell score among available milk components predicted by mid-infrared spectrometry on 590,083 test-day records from Walloon Region of Belgium collected between 2007 and 2009. Mean daily heritabilities and mean genetic correlations of these four traits were estimated using Gibbs sampling methodology applied to a multi-trait random regression test-day model with a subset of these records. Mean daily heritabilities of ind. lactoferrin content (0.34), ind. Na content (0.37) and lactose content (0.42) were higher then SCS (0.16) and mean genetic correlations were moderate (from -0.18 to -0.73), showing that these traits could be used together to describe udder health in genetic evaluations instead of SCS alone when clinical mastitis data are not available. [less ▲]

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See detailLongitudinal effects of muscular hypertrophy allele on milk production traits during the lactation using a novel equivalent model when molecular information is limited
Colinet, Frédéric ULg; Gengler, Nicolas ULg

Conference (2010, August)

Given that the mh allele causes the double muscling phenotype, this allele could also influence milk production traits of the dual purpose Belgian Blue cattle. However, all dual purpose Belgian Blue ... [more ▼]

Given that the mh allele causes the double muscling phenotype, this allele could also influence milk production traits of the dual purpose Belgian Blue cattle. However, all dual purpose Belgian Blue animals could not be genotyped. So, 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. Developed equations were modified to allow that not all animals were genotyped. As expected, the mh allele had negative effects on milk production traits. For the first three lactations, the average estimated allelic substitution effects were -0.074 % fat content and -158.7 kg milk per lactation (305 days). Moreover, effects of mh allele were not constant during the lactation. [less ▲]

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See detailLongitudinal effects of muscular hypertrophy allele on milk production traits during the lactation using a novel equivalent model when molecular information is limited
Colinet, Frédéric ULg; Gengler, Nicolas ULg

in Proceedings of the 9th World Congress on Genetics Applied to Livestock Production (2010, August)

Given that the mh allele causes the double muscling phenotype, this allele could also influence milk production traits of the dual purpose Belgian Blue cattle. However, all dual purpose Belgian Blue ... [more ▼]

Given that the mh allele causes the double muscling phenotype, this allele could also influence milk production traits of the dual purpose Belgian Blue cattle. However, all dual purpose Belgian Blue animals could not be genotyped. So, 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. Developed equations were modified to allow that not all animals were genotyped. As expected, the mh allele had negative effects on milk production traits. For the first three lactations, the average estimated allelic substitution effects were -0.074 % fat content and -158.7 kg milk per lactation (305 days). Moreover, effects of mh allele were not constant during the lactation. [less ▲]

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See detailFemale fertility expression in Walloon dairy cattle
Vanderick, Sylvie ULg; Bastin, Catherine ULg; Gengler, Nicolas ULg

Poster (2010, August)

A useful method to express female fertility of the Walloon dairy cattle using direct and indirect female fertility information was considered. Data were based on results of the genetic evaluation of ... [more ▼]

A useful method to express female fertility of the Walloon dairy cattle using direct and indirect female fertility information was considered. Data were based on results of the genetic evaluation of pregnancy rate for 606,328 Holstein cows and on INTERBULL proofs of female fertility for 88,496 bulls. A direct female fertility index (DFF), using INTERBULL proofs, was developed from results of a principal component analysis carried out on 6 published foreign female fertility indexes. An indirect female fertility index (IFF) was also developed from ten other traits evaluated in Walloon Region. Theory of selection index was used to combine DFF and IFF in a global index called combined female fertility index (CFF). This index allowed young bulls to have better reliabilities with an average increase of 12% leading to extra 4,019 of publishable bulls for female fertility. [less ▲]

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See detailA simulation approach for analyzing genomic data using a package of specific FORTRAN90 functions
Faux, Pierre ULg; Gengler, Nicolas ULg

Conference (2010, July 12)

A panel of FORTRAN 90 functions was developed to simulate the distribution of bi-allelic (e.g., SNP) genetic markers along a defined genome and the distribution of their alleles in a given population. The ... [more ▼]

A panel of FORTRAN 90 functions was developed to simulate the distribution of bi-allelic (e.g., SNP) genetic markers along a defined genome and the distribution of their alleles in a given population. The simulation program used 3 parameters, those related to the species studied (number of autosomes, average length of autosomes, average number of crossovers by chromosome), the number of markers and those related to the studied population (pedigree). The simulation proceeds in 3 steps: a) random choice of marker positions and allelic frequencies for the minor allele of each marker (range: 0.05 to 0.475), b) simulation of genotypes of the ancestors in the pedigree based on randomly chosen allelic frequencies and c) planned mating of the ancestors according to the pedigree and according to the average crossover rate as a genetic recombination parameter. The simulation returns a fully-genotyped population. This method is flexible because it can be applied to a wide range of cases (not restricted to a single species) and the FORTRAN functions can be extended and used to simulate phenotypes. It is also realistic, because it performs mating plans and selection of animals based on real pedigrees. Development of this simulation panel was the first step in research around advanced methods to compute and invert genomic relationship matrices. [less ▲]

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See detailWorking on a Method to Compute Inverse of Genomic Relationship Matrix from Sparse Matrices
Faux, Pierre ULg; Misztal, Ignacy; Gengler, Nicolas ULg

Conference (2010, July 12)

Genomic relationships matrix (G) are dense matrices used in genomic prediction of dairy cattle. As the number of genotyped animals will increase, an approximation of the inverse of genomic relationships ... [more ▼]

Genomic relationships matrix (G) are dense matrices used in genomic prediction of dairy cattle. As the number of genotyped animals will increase, an approximation of the inverse of genomic relationships matrix is needed. We have developed a method based on a decomposition of G similar to decomposition of additive relationships matrix A. The method of inversion is tested on a set of simulated data. [less ▲]

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