References of "Gengler, Nicolas"
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See detailUsing test station and on-farm data for the genetic evaluation of Piétrain boars used on Landrace sows for growth performance
Dufrasne, Marie ULg; Rustin, Maité; Jaspart, Véronique et al

in Journal of Animal Science (2011), 89

The aim of this study was to develop a new genetic evaluation model to estimate the genetic merit of boars for growth based on 1) performance of their crossbred progeny fattened in the test station and 2 ... [more ▼]

The aim of this study was to develop a new genetic evaluation model to estimate the genetic merit of boars for growth based on 1) performance of their crossbred progeny fattened in the test station and 2) their own performance or those of relatives from the on-farm testing system. The model was a bivariate random regression animal model with linear splines and was applied to Piétrain boars from the Walloon Region of Belgium mated with Landrace sows. Data contained 1) 12,610 BW records from the test station collected on 1,435 crossbred pigs from Piétrain boars and Landrace sows, and 2) 52,993 BW records from the on-farm testing system collected on 50,670 pigs with a breed composition of at least 40% Piétrain or Landrace. Since 2007, 56 Piétrain boars have been tested in the station. Data used to estimate variance components and breeding values were standardized for the age to take into account heterogeneity of variances and then pre-adjusted at 210 d of age to put all records on the same scale. Body weight records from the test station and from the on-farm testing system were considered as 2 different traits. The heterosis effect was modeled as fixed regression on the heterozygosity coefficient. As all test station animals were similarly crossbred, smaller variation in heterozygosity caused the sampling error of the regression estimate at 210 d to be larger in the test station than in on-farm data with estimates of 28.35 ± 14.55 kg and 9.02 ± 0.67 kg, respectively. Therefore, the most likely reason for the large differences in estimates was sampling. Heritability estimates ranged from 0.37 to 0.60 at 210 and 75 d, respectively, for test station BW and from 0.42 to 0.60 at 210 d and 175 d, respectively, for on-farm BW. Genetic correlation decreased when the age interval between records increased, and were greater between ages for test station than for on-farm data. Genetic correlations between test station and on-farm BW at the same age were high: 0.90 at 175 d and 0.85 at 210 d. For the 56 boars tested in the station, the average reliability of their EBV for ADG between 100 and 210 d was improved from 0.60 using only test station data to 0.69 using jointly test station and on-farm data. Based on these results, the new model developed was considered as a good method of detection of differences in growth potential of Piétrain boars based on test station and on-farm data. [less ▲]

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See detailMid-infrared predictions of lactoferrin content in bovine milk
Soyeurt, Hélène ULg; Bastin, Catherine ULg; Colinet, Frédéric ULg et al

in Journal of Dairy Science (2011), 94(E-suppl.1), 714

Lactoferrin (LF) is a glycoprotein present in milk and active in the immune system of cows and humans. Therefore, an inexpensive and rapid analysis to quantify this protein is desirable. A previous study ... [more ▼]

Lactoferrin (LF) is a glycoprotein present in milk and active in the immune system of cows and humans. Therefore, an inexpensive and rapid analysis to quantify this protein is desirable. A previous study reported the potential to quantify LF from the mid-infrared (MIR) spectrometry from 69 milk samples. Through the European RobustMilk project (www.robustmilk.eu), 3,606 milk samples were collected in Belgium, Ireland, and Scotland from individual cows and analyzed using a MIR MilkoScanFT6000 spectrometer. Milk LF content was quantified using ELISA in duplicate. Average ELISA data with a CV lower than 5% were used. After the detection of spectral and ELISA outliers, the calibration set contained 2,499 samples. An equation to predict LF content from MIR was developed using partial least squared regression. A first derivative pre-treatment of spectra was used to correct the baseline drift. To improve the repeatability of the spectral data, a file which contained the spectra of samples analyzed on 5 spectrometers was used during the calibration. The lactoferrin mean was 159.28 mg/l of milk with a SD of 97.21 mg/l of milk. The calibration (C) coefficient of determination (R2) was equal to 0.73 with a standard error (SE) of calibration of 50.54 mg/l of milk. A cross-validation (CV) was used to assess the robustness of the equation. R2 CV was 0.72 with a SE-CV of 51.16 mg/l of milk. An external validation (V) was conducted on 150 milk samples collected in Belgium. The SE of prediction (SEP) was 59.17 mg/L of milk. The similarity between R2 C and R2CV as well as between SE-C and SE-CV and between SE-CV and SEP confirms the equations developed are robust. The correlation between predicted and measured LF values was 0.71. This lower value compared with the one obtained from the calibration set (0.85) could be explained by the low ELISA reproducibility (16.24% ± 25.51%). If the developed equation is used to clean the validation data set, a total of 16 samples can be deleted. The validation coefficient for these 134 samples increased to 0.82. From these results, the developed equation could be used for screening the dairy cow population for breeding purposes. [less ▲]

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See detailPhenotypic and genetic variability of production traits and milk fatty acid contents across days in milk for Walloon Holstein first-parity cows.
Bastin, Catherine ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

in Journal of Dairy Science (2011), 94(8), 4152-63

The objective of this study was to assess the phenotypic and genetic variability of production traits and milk fatty acid (FA) contents throughout lactation. Genetic parameters for milk, fat, and protein ... [more ▼]

The objective of this study was to assess the phenotypic and genetic variability of production traits and milk fatty acid (FA) contents throughout lactation. Genetic parameters for milk, fat, and protein yields, fat and protein contents, and 19 groups and individual FA contents in milk were estimated for first-parity Holstein cows in the Walloon Region of Belgium using single-trait, test-day animal models and random regressions. Data included 130,285 records from 26,166 cows in 531 herds. Heritabilities indicated that de novo synthesized FA were under stronger genetic control than FA originating from the diet and from body fat mobilization. Estimates for saturated short- and medium-chain individual FA ranged from 0.35 for C4:0 to 0.44 for C8:0, whereas those for monounsaturated long-chain individual FA were lower (around 0.18). Moreover, de novo synthesized FA were more heritable in mid to late lactation. Approximate daily genetic correlations among traits were calculated as correlations between daily breeding values for days in milk between 5 and 305. Averaged daily genetic correlations between milk yield and FA contents did not vary strongly among FA (around -0.35) but they varied strongly across days in milk, especially in early lactation. Results indicate that cows selected for high milk yield in early lactation would have lower de novo synthesized FA contents in milk but a slightly higher content of C18:1 cis-9, indicating that such cows might mobilize body fat reserves. Genetic correlations among FA emphasized the combination of FA according to their origin: contents in milk of de novo FA were highly correlated with each other (from 0.64 to 0.99). Results also showed that genetic correlations between C18:1 cis-9 and other FA varied strongly during the first 100 d in milk and reinforced the statement that the release of long-chain FA inhibits FA synthesis in the mammary gland while the cow is in negative energy balance. Finally, results showed that the FA profile in milk changed during the lactation phenotypically and genetically, emphasizing the relationship between the physiological status of cow and milk composition. [less ▲]

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See detailNew method to combine molecular and pedigree relationships
Bömcke, Elisabeth ULg; Soyeurt, Hélène ULg; Szydlowski, Maciej et al

in Journal of Animal Science (2011), 89

Relationship coefficients are traditionally based on pedigree data. Today, with the development of molecular techniques, they are often completely replaced by coefficients calculated from molecular data ... [more ▼]

Relationship coefficients are traditionally based on pedigree data. Today, with the development of molecular techniques, they are often completely replaced by coefficients calculated from molecular data. Examples are relationships from microsatellites for biodiversity studies but also genomic relationships from SNP as currently used in genomic prediction of breeding values. There are, however, many situations in which optimal combination of both sources would be the best solutions. Obviously, this is the case for incompletely genotyped populations, but also when pedigree information is sparse. Also, markers, even dense ones, do not reflect the whole genome and therefore give only an incomplete picture of relationships. The main objective of this study was therefore to develop a method to calculate a relationship matrix by the combination of molecular and pedigree data. It will be useful for all situations where pedigree and molecular data are available. In this study, based on simulations of pedigree and marker data, we used partial least squares regression and linear regression to combine total allelic relationship coefficients calculated for each marker with additive relationship coefficients calculated from incomplete pedigree. The results showed that the greatest advantage of this method, compared with the one that replaces a part of the pedigree-based relationship matrix by a genomic relationship matrix, is that adding the partial pedigree data allows for the correction of the molecular coefficient for the ungenotyped part of the genome. [less ▲]

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See detailConstruction of individual breeding values for feed intake of Piétrain boars based on mean pen feed intake, weight and weight gain test station records
Dufrasne, Marie ULg; Jaspart, Véronique; Wavreille, José et al

in Journal of Animal Science (2011), 89(E-Suppl.1), 474-475

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See detailSystème d'évaluation génétique des verrats Piétrain en croisement en Wallonie
Dufrasne, Marie ULg; Jaspart, Véronique; Wavreille, José et al

Diverse speeche and writing (2011)

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See detailIs there value in maintaining small populations ? Example of the Dual-Purpose Belgian Blue breed.
Gengler, Nicolas ULg; Soyeurt, Hélène ULg; Bastin, Catherine ULg et al

in Journal of Dairy Science (2011), 94(E-suppl.1), 664

Current status of thinking on genomic selection in dairy cattle is mostly major breed centric (e.g., Holstein) and only for traditional traits (e.g., milk yields). Once you depart from this, it becomes ... [more ▼]

Current status of thinking on genomic selection in dairy cattle is mostly major breed centric (e.g., Holstein) and only for traditional traits (e.g., milk yields). Once you depart from this, it becomes obvious that different, often related, issues appear (e.g., lack of large training populations, need for expensive recording of new phenotypes). Also, there is an urgent need to rethink issues that are important for sustainability of dairy production (e.g., added value foods, animal robustness). In this context, small populations (breeds/lines) could represent a potential source of extra information to justify their maintenance. As marker densities increase, efficient dissection of different selection histories of divergent breeds or lines, potentially identifying pockets of unexploited variability will increase. A current example from the Belgian (Walloon) perspective is the Dual Purpose (DP) line of the Belgian Blue Breed (BBB), with presently around 4500 breeding females, for historical reason of which only 1500 have good pedigrees, and which is present in Belgium and northern France. Recent research, done on this line, showed its tendency to produce less saturated milk fat and to have better fertility. Results indicated that it could stay competitive in specific markets, especially because of largely increased meat value. Currently, the myostatin mutation is largely used for breeding purposes. To assess the genetic diversity of the breed, recently, over 200 genotypes (SNP50K) for nearly all breeding bulls of the last 20 years became available. HD genotypes should be available in the near future, also allowing to access selection history of this breed as being in between the 2 extreme breeds: Beef BBB (with which it shares a recent history) and Holstein-Friesian (which is related through its geographic proximity over centuries). Finally, genomic selection for DP-BBB will need to consider a single step type approach without the need of reference population and potentially relying heavily on SNP3K of cows, also with the objective to recreate relationships between animals of interest. [less ▲]

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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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