References of "Gengler, Nicolas"
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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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See detailHeterogeneity of residuals variances of milk fatty acids in dairy cattle
Arnould, Valérie ULg; Soyeurt, Hélène ULg; Vanderick, Sylvie ULg et al

in Journal of Dairy Science (2010, July), 88(E-Suppl. 2), 744

Routine genetic evaluation for milk fatty acids is under development in the Walloon Region of Belgium. The objective of this study was to test the heterogeneity of residual variances and therefore ... [more ▼]

Routine genetic evaluation for milk fatty acids is under development in the Walloon Region of Belgium. The objective of this study was to test the heterogeneity of residual variances and therefore indirectly the potential need to adjust for this heterogeneity if it exists. The residuals were computed as the difference between the observed and the estimated values using a multi-trait random regression test-day model, similar to the Walloon routine model, used for first lactation only milk yield, quantities and percentages of protein (PROT) and fat (FAT), content of saturated fatty acids in milk (g/100g of milk, SAT) and, content of mono-unsaturated fatty acids in milk (g/100g of milk, MONO). Residuals were considered homogeneous inside strata defined, among others, by weeks of lactation, by days in milk and by calendar months of test date. About 6,687,000 records were available for milk yield and for FAT and PROT parameters. For SAT and for MONO, about 184,000 records were available in this database. Means of residuals were stable and close to zero for all traits. Variances were more variable for MONO and SAT than for milk yield, for example. Daily and weekly variances tended to decrease at the end of the lactation (50%). When the variances were computed by month of test date, some variations were observed and some periods of year were more marked. In conclusion, the observed residual variances were less stable for MONO and SAT. We can conclude that introduction for heterogeneous residual variance is more important for the new traits (MONO, SAT) than it was for the old, traditional ones. [less ▲]

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See detailHeterogeneity of residuals variances of milk fatty acids in dairy cattle
Arnould, Valérie ULg; Soyeurt, Hélène ULg; Vanderick, Sylvie ULg et al

Conference (2010, July)

Routine genetic evaluation for milk fatty acids is under development in the Walloon Region of Belgium. The objective of this study was to test the heterogeneity of residual variances and therefore ... [more ▼]

Routine genetic evaluation for milk fatty acids is under development in the Walloon Region of Belgium. The objective of this study was to test the heterogeneity of residual variances and therefore indirectly the potential need to adjust for this heterogeneity if it exists. The residuals were computed as the difference between the observed and the estimated values using a multi-trait random regression test-day model, similar to the Walloon routine model, used for first lactation only milk yield, quantities and percentages of protein (PROT) and fat (FAT), content of saturated fatty acids in milk (g/100g of milk, SAT) and, content of mono-unsaturated fatty acids in milk (g/100g of milk, MONO). Residuals were considered homogeneous inside strata defined, among others, by weeks of lactation, by days in milk and by calendar months of test date. About 6,687,000 records were available for milk yield and for FAT and PROT parameters. For SAT and for MONO, about 184,000 records were available in this database. Means of residuals were stable and close to zero for all traits. Variances were more variable for MONO and SAT than for milk yield, for example. Daily and weekly variances tended to decrease at the end of the lactation (50%). When the variances were computed by month of test date, some variations were observed and some periods of year were more marked. In conclusion, the observed residual variances were less stable for MONO and SAT. We can conclude that introduction for heterogeneous residual variance is more important for the new traits (MONO, SAT) than it was for the old, traditional ones. [less ▲]

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See detailFeasibility of a genetic evaluation for milk fatty acids in dairy cattle
Soyeurt, Hélène ULg; Arnould, Valérie ULg; Vanderick, Sylvie ULg et al

Conference (2010, July)

Recent development of equations based on mid-infrared (MIR) spectrometry for the prediction of milk fatty acid (FA) contents allows their measurement on a large scale during performance recording. The ... [more ▼]

Recent development of equations based on mid-infrared (MIR) spectrometry for the prediction of milk fatty acid (FA) contents allows their measurement on a large scale during performance recording. The objective was to show that a genetic evaluation for milk FA in dairy cattle is feasible in the Walloon region of Belgium and to report first results. Estimated breeding values (EBV) and associated reliabilities (REL) were computed using a multi-trait test-day animal model similar to the one used for the routine genetic evaluation for yield traits. Studied traits were first lactation test-day milk, fat and protein yields, fat (FAT) and protein contents, and content of saturated fatty acids in milk (g/100g of milk, SAT). More than 6,700,000 records were available for common production and content traits and 194,000 records were used for SAT. Used variance components were estimated using REML. The average SAT content was 2.79% with a standard deviation (SD) of 0.50%. A total of 1,707 Holstein bulls used in Walloon Region had REL superior to 0.49 for all studied traits. REL for SAT ranged from 0.53 to 0.99. A total of 1,217 bulls had REL superior to 0.74. SD of EBV for SAT was 0.20%. The maximum and minimum SAT EBV values were 0.89% and -0.69%, respectively. In order to have a direct measure of the part of FAT that is not due to SAT, a new trait (dSAT) was post-evaluated and defined as difference between expected SAT EBV for a given FAT EBV and the estimated EBV for SAT. This new trait can be assumed to be a direct predictor of the content of unsaturated fatty acids in fat. The interest is that this trait cannot be accurately predicted directly by MIR. The maximum and minimum EBV for dSAT for the 1,707 bulls were -0.28% and 0.24%, respectively. Based on these results, a genetic evaluation for milk fatty acids is feasible. In the bull population used recently, a genetic variability for dSAT exists and could be used to improve the milk fat composition. [less ▲]

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See detailImprovements and validation of mid-infrared predictions of milk fatty acid
Soyeurt, Hélène ULg; McParland, Sinead; Donagh, Berry et al

Conference (2010, July)

The development of mid-infrared equations to predict the milk fatty acid (FA) content of milk allows prompt analysis of large numbers of samples. The first aim was to improve these predictions by ... [more ▼]

The development of mid-infrared equations to predict the milk fatty acid (FA) content of milk allows prompt analysis of large numbers of samples. The first aim was to improve these predictions by comparing 6 statistical approaches. The second one was to validate the new equations using an independent sample set. The calibration set contained 239 spectrally different Belgian milk samples collected for over 2 years from several cows and breeds. FA were quantified by gas chromatography (GC). Statistical approaches tested were 1) partial least squares regression (PLS), 2) PLS and first derivative, 3) PLS and repeatability file (RF), 4) PLS, first derivative and RF, 5) PLS, second derivative, and 6) PLS, second derivative and RF. This last file contained spectra obtained from the same samples using 5 spectrometers. Cross-validation (CV) used 20 groups from the calibration set. Methods were compared using the ratio of the standard deviation of GC values to the standard error of CV (RPD). An external validation permitted a second comparison and was done using 362 samples collected for one year from multiple breeds and cows in Belgium, Ireland, and Scotland. Different RPD values were obtained by the 6 methods. Generally the equations developed using method 4 gave better results suggesting the adaptation of the methodology to the studied FA. It confirms by the obtained validation coefficients of determination. Highest values were observed for the equations with the highest RPD values except for C18:0. The ability to predict FA using method 4 gave superior results to those shown in previous publications. [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

Conference (2010, June 04)

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 detailGenetic evaluation for body condition score in the Walloon Region of Belgium
Bastin, Catherine ULg; Gillon, Alain ULg; Massart, Xavier et al

Conference (2010, June 02)

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See detailPotential estimation of titratable acidity in cow milk using mid-infrared spectrometry
Colinet, Frédéric ULg; Soyeurt, Hélène ULg; Anceau, Christine ULg et al

Conference (2010, June)

Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the ... [more ▼]

Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the phases of milk coagulation. The objective of this research was to study the feasibility of prediction of titratable acidity directly in bovine milk using mid-infrared spectrometry. In order to maximize the variability in the measurements of titratable acidity, milk samples were collected on basis of several criteria (e.g. breeds). The titratable acidity was recorded as Dornic degree. All samples were also analyzed by MIR spectrometry. Using partial least squares regressions and first derivative pretreatment of spectral data, a calibration equation was built to predict the Dornic degree in cow milk. First results were promising and showed the potentiality to this calibration. The calibration and cross-validation coefficients of determination were 92.25 and 89.88 %, respectively. Moreover, the ratio of standard error of prediction to standard deviation was 3.13 and permits us to consider the calibration equation as usable in most application such as scientific researches and the screening of the Walloon dairy herd particularly in order to improve the milk coagulation properties. [less ▲]

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See detailEvaluation génétique des verrats Piétrain en croisement en Wallonie
Dufrasne, Marie ULg; Jaspart, Véronique; Wavreille, José et al

Diverse speeche and writing (2010)

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See detailDevelopment of a new crossbred based evaluation for carcass quality of Piétrain boars in the Walloon Region of Belgium
Dufrasne, Marie ULg; Hammami, Hedi ULg; Jaspart, Véronique et al

in Proceedings of the British Society of Animal Science and the Agricultural Research Forum (2010, April)

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See detailEvaluation génétique des verrats Piétrain en Wallonie
Dufrasne, Marie ULg; Jaspart, Véronique; Wavreille, José et al

Article for general public (2010)

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See detailEvaluation génétique des verrats Piétrain en croisement en Wallonie
Dufrasne, Marie ULg; Hammami, Hedi ULg; Gengler, Nicolas ULg et al

Diverse speeche and writing (2010)

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See detailMotives and values in farming local cattle breeds in Europe: a survey on 15 breeds
Gandini, G.; Avon, L.; Bohte-Wilhelmus, D. et al

in Animal Genetic Resources (2010), 47

Within the EURECA project (Towards self-sustainable EUropean REgional CAttle breeds), we interviewed a total of 371 farmers of 15 local cattle breeds in eight European countries. Besides collecting data ... [more ▼]

Within the EURECA project (Towards self-sustainable EUropean REgional CAttle breeds), we interviewed a total of 371 farmers of 15 local cattle breeds in eight European countries. Besides collecting data on farmers, land use, herd composition and economic role of cattle, we aimed at understanding farmers’ motives and values in keeping local cattle. The most frequent first reason to keep the local breed was productivity, followed by tradition. When comparing the local breed with a mainstream breed, only in four breeds was productivity considered the same, while in three breeds more than 50 percent of farmers valued the local breed as more profitable. The local breed was valued as always superior or the same on functional traits. Farmers were asked which type of appreciation they thought representatives of various stakeholders had on their local breed: a positive appreciation was observed in 33 percent of farmers. On average across breeds, 39 percent of farmers expect to increase the size of their herd in the next few years and 5 percent plan to give up farming. The degree of dependence of farmers on economic incentives was estimated by asking farmers their expected behaviour under three scenarios of change of subsidies. Most farmers demanded activities for promoting local breed farming. The results are discussed in terms of breed sustainability and conservation. [less ▲]

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See detailPotential estimation of titratable acidity in cow milk using mid-infrared spectrometry
Colinet, Frédéric ULg; Soyeurt, Hélène ULg; Anceau, Christine ULg et al

in ICAR Technical Series (2010), 14

Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the ... [more ▼]

Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the phases of milk coagulation. The objective of this research was to study the feasibility of prediction of titratable acidity directly in bovine milk using mid-infrared spectrometry. In order to maximize the variability in the measurements of titratable acidity, milk samples were collected on basis of several criteria (e.g. breeds). The titratable acidity was recorded as Dornic degree. All samples were also analyzed by MIR spectrometry. Using partial least squares regressions and first derivative pretreatment of spectral data, a calibration equation was built to predict the Dornic degree in cow milk. First results were promising and showed the potentiality to this calibration. The calibration and cross-validation coefficients of determination were 92.25 and 89.88 %, respectively. Moreover, the ratio of standard error of prediction to standard deviation was 3.13 and permits us to consider the calibration equation as usable in most application such as scientific researches and the screening of the Walloon dairy herd particularly in order to improve the milk coagulation properties. [less ▲]

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