References of "Gengler, Nicolas"
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See detailFirst approaches for a combined use of microsatellites and pedigree data to estimate relationships.
Bömcke, Elisabeth ULg; Gengler, Nicolas ULg

in Book of Abstract of the 58th Annual Meeeting of the European Association for Animal Production (2007, August)

The main objective of conservation is the preservation of genetiv diversity. Among several tools recommended to measure genetic variability, relationships coefficients are often used. They can be ... [more ▼]

The main objective of conservation is the preservation of genetiv diversity. Among several tools recommended to measure genetic variability, relationships coefficients are often used. They can be estimated from pedigree but also from direct knowledge of hte genotype. The Skyros pony is an example of a small breed concerned by the management of genetic variability. However,the analysis of the pedigree showed its very poor quality. A part of the population was therefore genotyped for 16 microstellites and two estimators of relationships were tested: the Lynch & Ritland (L&R) (anly based on genotypes and described as having the best performances for all population comositionsof the mammal species) and a new estimator (developed for this study and combining pedigree and microsatellite information). In order to compare the results, a Principal Component Analysis (PCA) was performed. The new estimator explained a higher percentage of information within the 3 principal factors of the PCA (41.99%) than the L&R estimator (20.61%). The graphic PCA representation showed a better separation between the reference group and the rest of the populationin the case of the new estimator. The new estimator showed interesting preliminary results and results support interest in combining information in case of incomplete pedigrees and/or use of a limited number of markers. [less ▲]

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See detailFirst steps to model milk urea in a management perspective
Bastin, Catherine ULg; Gillon, Alain ULg; Laloux, Laurent et al

Conference (2007, July)

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See detailProduire de la viande et du lait avec la Blanc-Bleu Belge de type mixte
Bastin, Catherine ULg; Mayeres, Patrick; Bertozzi, Carlo et al

in 12ième Carrefour des Productions animales: Le marché de la viande bovine, enjeux et perspectives: Gembloux, le 24 janvier 2007 (2007, January 24)

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See detailProduire de la viande et du lait avec la Blanc-Bleu Belge de type mixte
Bastin, Catherine ULg; Mayeres, Patrick; Bertozzi, Carlo et al

Poster (2007, January 24)

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See detailA simple method to approximate gene content in large pedigree populations: application to the myostatin gene in dual-purpose Belgian Blue cattle
Gengler, Nicolas ULg; Mayeres, P.; Szydlowski, M.

in Animal (2007), 1(1), 21-28

Gene content is the number of copies of a particular allele in a genotype of an animal. Gene content can be used to study additive gene action of candidate gene. Usually genotype data are available only ... [more ▼]

Gene content is the number of copies of a particular allele in a genotype of an animal. Gene content can be used to study additive gene action of candidate gene. Usually genotype data are available only for a part of population and for the rest gene contents have to be calculated based on typed relatives. Methods to calculate expected gene content for animals on large complex pedigrees are relatively complex. in this paper we proposed a practical method to calculate gene content using a linear regression. The method does not estimate genotype probabilities but these can be approximated from gene content assuming Hardy-Weinberg proportions. The approach was compared with other methods on multiple simulated data sets for real bovine pedigrees of 1082 and 907 903 animals. Different allelic frequencies (0.4 and 0.2) and proportions of the missing genotypes (90, 70, and 50%) were considered in simulation. The simulation showed that the proposed method has similar capability to predict gene content as the iterative peeling method, however it requires less time and can be more practical for large pedigrees. The method was also applied to real data on the bovine myostatin locus on a large dual-purpose Belgian Blue pedigree of 235 133 animals. It was demonstrated that the proposed method can be easily adapted for particular pedigrees. [less ▲]

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See detailBayesian approach to integrate molecular data into genetic evaluations
Gengler, Nicolas ULg; Verkenne, Catherine

in Interbull Bulletin (2007), 37

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See detailGenetic Parameters of Butter Hardness Estimated by Test-Day Model
Soyeurt, Hélène ULg; Dehareng, Frédéric; Bertozzi, Carlo et al

in Interbull Bulletin (2007), 37

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See detailPrinicpal components approach for estimating heritability of mid-infrared (MIR) spectrum in bovine milk
Soyeurt, Hélène ULg; Tsuruta, Shogo; Misztal, Ignacy et al

in Book of Abstracts of the 58th Annual Meeting of the European Association for Animal Production (2007)

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See detailResponse and genetic analysis of malathion-specific resistant Tribolium castaneum (Herbst) in relation to population density
Assie, L. K.; Francis, Frédéric ULg; Gengler, Nicolas ULg et al

in Journal of Stored Products Research (2007), 43(1), 33-44

Extensive use of malathion for pest control on stored cereals has resulted in worldwide resistance in red flour beetles, Tribolium castaneum. In this paper we investigate population density effects on the ... [more ▼]

Extensive use of malathion for pest control on stored cereals has resulted in worldwide resistance in red flour beetles, Tribolium castaneum. In this paper we investigate population density effects on the malathionspecific resistance in PRm, a strain from the Philippines, in an integrated resistance management framework. Two populations of malathion-specific resistant (PRm) and a malathion- susceptible strain of T castanewn were bred at different densities: low (4 adults/g) and high (12 adults/g) density on wheat plus brewer's yeast in the laboratory. After eight generations, slopes of probit regression lines and LC50 values were used to monitor the effect of insect rearing density on the progression of malathion-specific resistance. The LC50 of the malathion- susceptible strain (Asm) did not change significantly during selection while LC(50)s varied for both the high-density and low-density lines of PRm, the LC50 of malathion ranged from 27.51 to 34.06 and from 21.14 to 29.39 Vg malathion cm(-2) for high and low density, respectively. More than 33 generations were required to achieve a 10-fold increase of resistance for the low-density line compared to only 17 generations for the high-density line. Calculations from published formulae suggested that the malathion-specific resistance of both high- and low-density lines was under monofactorial control, with complete dominance. The data showed that environmental factors such as population density differences in insect rearing and development may influence the heritability of resistance. Furthermore, the variability in results published worldwide on resistance emphasises the need to standardize test conditions across laboratories. (c) 2005 Published by Elsevier Ltd. [less ▲]

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See detailEstimation of phenotypic and genetic parameters for weight gain and weight at fixed ages in the double-muscled Belgian Blue Beef breed using field records
Coopman, F.; Krafft, A.; Dewulf, J. et al

in Journal of Animal Breeding & Genetics (2007), 124(1), 20-25

In the double-muscled Belgian Blue beef (DM-BBB) breed, selection focuses on muscular conformation and not on weight gain and higher weight. There are very few studies on growth in the DM-BBB using field ... [more ▼]

In the double-muscled Belgian Blue beef (DM-BBB) breed, selection focuses on muscular conformation and not on weight gain and higher weight. There are very few studies on growth in the DM-BBB using field records. Therefore, farms have no available useful figures on weight at fixed ages and weight gain for the DM-BBB. This study describes and evaluates live weights of DM-BBB animals. All the data were gathered on farms in Belgium. It was found that a male DM-BBB weighs an average of 51 kg at birth, 98 kg at 3 months, 242 kg at 7 months, 430 kg at 13 months and 627 kg at 20 months. Between the age of 7 and 20 months, weight gain is more than 1200 g a day. Females weigh 47 kg at birth, 96 kg at 3 months, 189 kg at 7 months and 332 kg at 13 months. For males, estimates of heritability for weights at 7, 13 and 20 months were between 0.21 and 0.36. The heritability for weight gain between 13 and 20 months was 0.13. This demonstrates that it is possible to select for higher weights and for increased growth between 13 and 20 months. Animals having high weights at a young age (7 and 13 months) tend to have also high weight at slaughtering age (20 months; r(g) between 0.81 and 0.98), but no additional growth between 13 and 20 months (r(g) between -0.09 and 0.00). High weight at 20 months is partially due to growth between 13 and 20 months (r(g) = 0.49). [less ▲]

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See detailShort communication: Genetic evaluation of milking speed for brown Swiss dairy cattle in the United States
Wiggans, G. R.; Thornton, L. L. M.; Neitzel, R. R. et al

in Journal of Dairy Science (2007), 90(2), 1021-1023

Genetic parameters and relative breeding values were estimated for milking speed of US Brown Swiss dairy cattle. Owner-recorded milking-speed scores on a scale of 1 (slow) to 8 (fast) were collected by ... [more ▼]

Genetic parameters and relative breeding values were estimated for milking speed of US Brown Swiss dairy cattle. Owner-recorded milking-speed scores on a scale of 1 (slow) to 8 (fast) were collected by the Brown Swiss Association as part of its linear type appraisal program starting in 2004. Data were 7,366 records for 6,666 cows in 393 herds. The pedigree file included information for 21,458 animals born in 1985 or later. Six unknown-parent groups that each included 4 birth years were defined. The model included fixed effects for herd appraisal date and parity-lactation stage and random effects for permanent environment, animal, and error. Within parity (1, 2, and >= 3), 6 groups were defined: unknown calving date, four 90-d lactation stages, and lactations with > 400 d in milk. Heritability of 0.22 and repeatability of 0.42 were estimated by average-information REML; residual variance was 1.13. Little trend in estimated breeding value was found for cows born from 1999 through 2002. Although solutions increased with lactation stage for first-parity cows by 0.37, no clear trend was found for later parities. Genetic evaluations for milking speed were expressed as relative breeding values with a mean of 100 and a standard deviation of 5. The 121 bulls with >= 10 daughters had milking speed evaluations that ranged from 83 to 112 and had correlations of 0.56 with productive life evaluations and -0.40 with somatic cell score evaluations. The association of faster milking speed with lower somatic cell score was not expected. The moderate heritability found for milking speed indicates that the evaluations (first released in May 2006) should be useful in detecting bulls with slow-milking daughters. [less ▲]

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See detailDetection and use of single gene effects in large animal populations
Gengler, Nicolas ULg; Abras, S.; Szydlowski, M. et al

in Journal of Dairy Science (2007), 90(Suppl. 1), 376-376

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See detailGenetic variability of lactoferrin content estimated by mid-infrared spectrometry in bovine milk
Soyeurt, Hélène ULg; Colinet, Frédéric ULg; Arnould, Valérie ULg et al

in Journal of Dairy Science (2007), 90(9), 4443-4450

The effects of lactoferrin (LF) on the immune system have already been shown by many studies. Unfortunately, the current methods used to measure LF levels in milk do not permit the study of the genetic ... [more ▼]

The effects of lactoferrin (LF) on the immune system have already been shown by many studies. Unfortunately, the current methods used to measure LF levels in milk do not permit the study of the genetic variability of lactoferrin or the performance of routine genetic evaluations. The first aim of this research was to derive a calibration equation permitting the prediction of LF in milk by mid-infrared spectrometry (MIR). The calibration with partial least squares on 69 samples showed a ratio of standard error of cross-validation to standard deviation equal to 1.98. Based on this value, the calibration equation was used to establish an LF indicator trait (predicted LF; pLF) on a large number of milk samples (n = 7,690). A subsequent study of its variability was conducted, which confirmed that stage of lactation and lactation number influence the overall pLF level. Small differences in mean pLF among 7 dairy breeds were also observed. The pLF content of Jersey milk was significantly higher than that in Holstein milk. Therefore, the choice of breed could change the expected LF level. Heritability estimated for pLF was 19.7%. The genetic and phenotypic correlations between somatic cell score and pLF were 0.04 and 0.26, respectively. As somatic cell score increases in presence of mastitis, this observation seems to indicate that pLF, or a function of observed pLF, compared with expected LF might have potential as an indicator of mastitis. The negative genetic correlation (−0.36) between milk yield and pLF could indicate an undesirable effect of selection for high milk production on the overall LF level. [less ▲]

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See detailSampling genotype configurations in large complex pedigree
Szydlowski, M.; Gengler, Nicolas ULg

in Journal of Dairy Science (2007), 90(Suppl. 1), 668-668

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See detailValLait - Lactation Curves Modelling
Gillon, Alain ULg; Gengler, Nicolas ULg

Computer development (2007)

calculation of 305-d lactation yields for Walloon dairy cows

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See detailGenetic diversity and joint-pedigree analysis of two importing Holstein populations.
Hammami, Hedi ULg; Croquet, Coraline; Stoll, Jean et al

in Journal of Dairy Science (2007), 90(7), 3530-41

Genetic diversity and relatedness between 2 geographically distant Holstein populations (in Luxembourg and Tunisia) were studied by pedigree analysis. These 2 populations have similar sizes and structures ... [more ▼]

Genetic diversity and relatedness between 2 geographically distant Holstein populations (in Luxembourg and Tunisia) were studied by pedigree analysis. These 2 populations have similar sizes and structures and are essentially importing populations. Edited pedigrees included 140,392 and 151,381 animals for Tunisia and Luxembourg, respectively. To partially account for pedigree completeness levels, a modified algorithm was used to compute inbreeding. The effective numbers of ancestors were derived from probabilities of gene origin for the 2 populations of cows born between 1990 and 2000. The 10 ancestors with the highest contributions to genetic diversity in the cow populations accounted for more than 32% of the genes. Eight of these 10 ancestors were the same in both populations. The rates of inbreeding were different in the 2 populations but were generally comparable to those found in the literature for the Holstein breed. Average inbreeding coefficients per year, estimated from the data, ranged from 0.91 and 0.50 in 1990 to 3.10 and 2.12 in 2000 for the Tunisian and Luxembourg populations, respectively. Genetic links have also strengthened with time. Average additive relationships between the 2 populations were as high as 2.2% in 2000. Results suggest that it would be possible to investigate genotype by environment interactions for milk traits using the Tunisian and Luxembourg dairy populations. [less ▲]

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See detailEstimation of heritability and genetic correlations for the major fatty acids in bovine milk
Soyeurt, Hélène ULg; Gillon, Alain ULg; Vanderick, Sylvie ULg et al

in Journal of Dairy Science (2007), 90(9), 4435-4442

The current cattle selection program for dairy cattle in the Walloon region of Belgium does not consider the relative content of the different fatty acids (FA) in milk. However, interest by the local ... [more ▼]

The current cattle selection program for dairy cattle in the Walloon region of Belgium does not consider the relative content of the different fatty acids (FA) in milk. However, interest by the local dairy industry in differentiated milk products is increasing. Therefore, farmers may be interested in selecting their animals based on the fat composition. The aim of this study was to evaluate the feasibility of genetic selection to improve the nutritional quality of bovine milk fat. The heritabilities and correlations among milk yield, fat, protein, and major FA contents in milk were estimated. Heritabilities for FA in milk and fat ranged from 5 to 38%. The genetic correlations estimated among FA reflected the common origin of several groups of FA. Given these results, an index including FA contents with the similar metabolic process of production in the mammary gland could be used, for example, to increase the monounsaturated and conjugated fatty acids in milk. Moreover, the genetic correlations between the percentage of fat and the content of C14:0, C12:0, C16:0, and C18:0 in fat were −0.06, 0.55, 0.60, and 0.84, respectively. This result demonstrates that an increase in fat content is not directly correlated with undesirable changes in FA profile in milk for human health. Based on the obtained genetic parameters, a future selection program to improve the FA composition of milk fat could be initiated. [less ▲]

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See detailFirst results of body condition score modeling for Walloon Holstein cows
Bastin, Catherine ULg; Laloux, Laurent; Gillon, Alain ULg et al

in Interbull Bulletin (2007), 37

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