References of "Gengler, Nicolas"
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See detailImplementing a National Routine Genetic Evaluation for Milk Fat Compositions as First Step Towards Genomic Predictions
Gengler, Nicolas ULg; Troch, Thibault ULg; Vanderick, Sylvie ULg et al

in Interbull Bulletin (2012), 46

Currently the Walloon Region of Belgium is one of the first regions in the World where mid-infra red (MIR) spectral data is recorded in routine for nearly all cows under milk recording. Based on this data ... [more ▼]

Currently the Walloon Region of Belgium is one of the first regions in the World where mid-infra red (MIR) spectral data is recorded in routine for nearly all cows under milk recording. Based on this data, in some herds collected since 2007, saturated (SFA) and monounsaturated fatty acid (MUFA) contents in milk are predicted for each test-day. Together with correlated traits as milk, fat and protein yields, estimated breeding values (EBV) are now computed in routine for SFA and MUFA starting in June 2012. A total of 499 821, 392 255, 277 465 fatty acid records were available in first, second and third lactation for this run. A restricted selection index, called NQI (nutritional quality index) was developed that puts a negative weight on SFA, a positive weight on MUFA and restricts changes in milk and fat yields to zero. By using this index for a constant fat content, milk fat will be selected to be less saturated with a high contribution from MUFA. Based on this system a single-step genomic evaluation is under development including the introduction of MACE breeding values for correlated traits. The final step is to offer for owners of genotyped animals, a service to provide them with genomically enhanced NQI. Similar systems are under development in Wallonia for other novel traits (e.g., methane emissions) based on the ability to predict them from MIR spectral data. [less ▲]

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See detailGenetic parameters for methane indicator traits based on milk fatty acids
Kandel, Purna Bhadra ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

Scientific conference (2012, February 14)

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See detailEstimation of genetic parameters for methane indicator traits based on milk fatty acids in dual purpose Belgian blue cattle
Kandel, Purna Bhadra ULg; Soyeurt, Hélène ULg; Gengler, Nicolas ULg

in Communications in Agricultural and Applied Biological Sciences (2012, February 10), 77(1), 21-25

The genetic parameters of CH4 indicators were estimated by single trait test-day models from 16,825 records collected on Walloon Dual Purpose Belgium Blue cows in their first 3 lactations. Fatty acid ... [more ▼]

The genetic parameters of CH4 indicators were estimated by single trait test-day models from 16,825 records collected on Walloon Dual Purpose Belgium Blue cows in their first 3 lactations. Fatty acid based CH4 indicators published in the literature were predicted from milk mid-infrared spectra using 597 calibration samples. For the indicator showing the highest link (R2 =0.88) with SF6 CH4 data, the average daily heritability was 0.21, 0.20 and 0.10 for each lactation, respectively. The sire genetic variability was on average 2.82 kg2 of CH4 per lactation. The genetic difference between the sires having cows eructing higher and lower CH4 was 10 kg of CH4 averaged per lactation. In conclusion, CH4 indicators can be predicted by MIR and the genetic variability of these traits seems to exist. [less ▲]

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See detailUsing fatty acid contents in milk to improve fertility of dairy cows?
Bastin, Catherine ULg; Berry, D.P.; Soyeurt, Hélène ULg et al

Poster (2012, February 10)

Improving dairy cow fertility by means of genetic selection has become increasingly important over the last years in order to overcome the declining cow fertility. This study investigated whether the ... [more ▼]

Improving dairy cow fertility by means of genetic selection has become increasingly important over the last years in order to overcome the declining cow fertility. This study investigated whether the fatty acids profile in milk could be used as an early predictor of genetic merit for fertility. Genetic covariances among 17 fatty acid contents in milk and the number of days from calving to conception were estimated from 29,792 first-parity Holstein cows. Results substantiated the unfavorable relationship among fertility and body fat mobilization in early lactation. Also, about 75% of the genetic variability of fertility was explained by the variability in milk fatty acids profile over the lactation indicating that these traits could be used to supplement genetic evaluations for fertility. [less ▲]

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See detailRelationships between methane emissions of dairy cattle and farm management.
Vanrobays, Marie-Laure ULg; Vanlierde, Amélie; Kandel, Purna Bhadra ULg et al

Poster (2012, February 10)

Livestock is considered as an important contributor to global methane emissions, predominately due to methanogenesis from ruminants. Moreover, these emissions also represent major losses of energy for ... [more ▼]

Livestock is considered as an important contributor to global methane emissions, predominately due to methanogenesis from ruminants. Moreover, these emissions also represent major losses of energy for dairy cows and therefore are linked to production efficiency. The on-going development of predictive equations (e.g., from milk composition) would allow to relate methane emissions to farm management (e.g., nutrition, environment) on a large scale in the Walloon Region of Belgium. Finally, by acquiring improved knowledge of these relationships, contributions to mitigate methane emissions could be based on an improved management of dairy herds. [less ▲]

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See detailEvaluation of the genetic diversity of honey bees, Apis mellifera L. in the Walloon Region and selection of strains tolerant to the mite Varroa destructor Anderson and Trueman
Leclercq, Gil ULg; Nguyen, Bach Kim ULg; Gengler, Nicolas ULg et al

Poster (2012, February 10)

For more than a decade, high losses of honey bee colonies have been noticed in several countries, including Belgium. Currently often the mite Varroa destructor is considered a main threat for beekeeping ... [more ▼]

For more than a decade, high losses of honey bee colonies have been noticed in several countries, including Belgium. Currently often the mite Varroa destructor is considered a main threat for beekeeping. In view of the inefficiency of the current chemical treatments, one of the solutions is to select honey bees tolerant to this parasite using genomic selection. To reach this objective the genetic diversity of honey bees needs first to be studied using mainly ‘Single Nucleotide Polymorphisms’ (SNP). Records and samples will be collected all over the Walloon Region in order to create an informative phenotypic and genomic data base that will be used for ‘Genome Wide Association Studies’ (GWAS) to detect associations between SNPs and tolerance, and to select bees tolerant to Varroa destructor. [less ▲]

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See detailVariability among morning and evening milk compositions during the lactation
Arnould, Valérie ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

Poster (2012, February 10)

The main objective of this study was to analyze milking-to-milking variability of milk yield and milk composition (such as fat and protein percentages and somatic cell count). Additional objective was to ... [more ▼]

The main objective of this study was to analyze milking-to-milking variability of milk yield and milk composition (such as fat and protein percentages and somatic cell count). Additional objective was to extend this analyze to the milk fat composition. Milk samples (n=195.960) were collected from 29.636 cows in 491 Luxembourg farms and analyzed by MIR spectrometry. The milk contents of saturated, mono-, poly- and unsaturated fatty acids, and short, medium and long chain fatty acids were predicted from the recorded MIR spectral data. As expected, the milk composition and the milk fat composition, are affected by several factors as the milking period and the days in milk. In practice, using separately milk evening and milk morning could be interesting for cheese or butter production. [less ▲]

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See detailIntegration of external information into genetic evaluations by a Bayesian procedure
Vandenplas, Jérémie ULg; Gengler, Nicolas ULg

Poster (2012, February 10)

One of the most important theoretical assumptions of methods used to assess genetic values is that all available information has to be considered simultaneously to obtain unbiased estimates. However, the ... [more ▼]

One of the most important theoretical assumptions of methods used to assess genetic values is that all available information has to be considered simultaneously to obtain unbiased estimates. However, the widespread international exchange of genetic material and, more recently, the important development of the genomic selection lead to the coexistence of different genetic evaluations. Therefore, the blending of the different sources of information is necessary to achieve better prediction. Integration of external information into genetic evaluations by a Bayesian procedure can partially resolve the problem under some assumptions. Results from such a method that also avoids double counting among external animals are highly similar to those from a joint evaluation. [less ▲]

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See detailGenetic correlations of days open with production traits and contents in milk of major fatty acids predicted by mid-infrared spectrometry.
Bastin, Catherine ULg; Berry, D. P.; Soyeurt, Hélène ULg et al

in Journal of Dairy Science (2012), 95(10), 6113-21

The objective of this study was to estimate the genetic relationships between days open (DO) and both milk production traits and fatty acid (FA) content in milk predicted by mid-infrared spectrometry. The ... [more ▼]

The objective of this study was to estimate the genetic relationships between days open (DO) and both milk production traits and fatty acid (FA) content in milk predicted by mid-infrared spectrometry. The edited data set included 143,332 FA and production test-day records and 29,792 DO records from 29,792 cows in 1,170 herds. (Co)variances were estimated using a series of 2-trait models that included a random regression for milk production and FA traits. In contrast to the genetic correlations with fat content, those between DO and FA content in milk changed considerably over the lactation. The genetic correlations with DO for unsaturated FA, monounsaturated FA, long-chain FA, C18:0, and C18:1 cis-9 were positive in early lactation but negative after 100 d in milk. For the other FA, genetic correlations with DO were negative across the whole lactation. At 5 d in milk, the genetic correlation between DO and C18:1 cis-9 was 0.39, whereas the genetic correlations between DO and C6:0 to C16:0 FA ranged from -0.37 to -0.23. These results substantiated the known relationship between fertility and energy balance status, explained by the release of long-chain FA in early lactation, from the mobilization of body fat reserves, and the consequent inhibition of de novo FA synthesis in the mammary gland. At 200 d in milk, the genetic correlations between DO and FA content ranged from -0.38 for C18:1 cis-9 to -0.03 for C6:0. This research indicates an opportunity to use FA content in milk as an indicator trait to supplement the prediction of genetic merit for fertility. [less ▲]

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See detailBayesian integration of external information into the single step approach for genomically enhanced prediction of breeding values
Vandenplas, Jérémie ULg; Misztal, Ignacy; Faux, Pierre ULg et al

in Journal of Dairy Science (2012), 95(Supplement 2),

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See detailGenetic variation in heat stress tolerance of Holsteins producing under a continental temperate environment
Hammami, Hedi ULg; Arnould, Valérie ULg; Bormann, Jeanne et al

Poster (2012)

Under projected climate changes, considerations for heat stress tolerance but also for genotype by environment interactions should enter breeding decisions, both for importing, but also exporting ... [more ▼]

Under projected climate changes, considerations for heat stress tolerance but also for genotype by environment interactions should enter breeding decisions, both for importing, but also exporting countries. Most studies concerning the breeding strategies on heat stress tolerance used the temperature humidity index (THI) to assess the thermal stress in a given environment and assumed a specific threshold to each studied population with the same response to each individual above this threshold. Recently new comprehensive thermal indices (TI) integrating radiation solar, wind speed, in addition to temperature and relative humidity were developed. Therefore, the aim of this study is advanced modelling of milk yield trait to evaluate the genetic variation in heat stress tolerance of Holsteins in a temperate environment using random regressions models and six new comprehensive TI. A total of 107,350 test day milk records were available for 12,099 primiparous Holsteins calving from 2000 to 2010. Test-day milk records were merged with meteorological data from 14 public weather stations across Luxembourg. Daily values of 6 new comprehensive TI (3 THI and 3 apparent temperature indices) were calculated by averaging hourly TI over 24 hours. The average distance between herds and their meteorological reference station was of 16 km. Sensitivity of cows to the climate environmental conditions was modelled by applying a reaction norm for each animal, representing its EBV for milk yield on values of the TI on the day in milk (DIM). Six separate random regression models were applied using time-dependent (DIM) and specific TI-dependent covariates. Random effects were additive genetic, permanent environmental, and herd year modelled with Legendre polynomials of order 2 for both DIM and TI. Genetic variances of the different TI evaluated in this study represent 27 to 30% of their correspondent variances for DIM effect. Permanent environmental and genetic variances of TI effect were in the same range. Additive genetic variances and heritabilities for daily milk yield slightly decreased with increasing degrees of the different THI and apparent temperature indices. The average daily milk heritability overall the lactation at the mean of each of the six TI was of 0.28. Genetic correlations between adjacent points across the lactation were > 0.90. Correlations between extreme distant DIM (e.g. early and late lactation stage) were reduced at 0.38 to 0.52. The overall genetic correlations between the different values of each TI remain high (> 0.85). EBV’s summing regular additive effect (DIM effect) and tolerance to heat stress (TI effect) were computed for several combinations of DIM and TI values. Ranking for sires and cows did not change among the 6 heat stress indicators. The correlations between EBVs estimated with the six models were greater than 0.90. In conclusion, the different models depicted genetic variation of milk yield among combinations of DIM and TI levels without defining thresholds in advance. Genetic variation was slightly lower when TI values exceed the thermoneutral zone. Breeding for reduced thermal sensitivity using any of the six indicators of heat stress evaluated in this study is possible. The indicator TI2 representing the adjusted THI for radiation solar and wind speed is favoured because it was the indicator that did identify the highest yearly milk losses under this continental temperate environment. [less ▲]

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See detailA recursive algorithm for decomposition and creation of the inverse of the genomic relationship matrix
Faux, Pierre ULg; Gengler, Nicolas ULg; Misztal, Ignacy

in Journal of Dairy Science (2012), 95(10), 6093-6102

As the number of genotyped animals increases, some genomic prediction models have issues related to inversion of the genomic relationship and related matrices. We developed a recursive algorithm to ... [more ▼]

As the number of genotyped animals increases, some genomic prediction models have issues related to inversion of the genomic relationship and related matrices. We developed a recursive algorithm to approximate the inverses of those matrices. The algorithm converges after a few rounds of recursion, but additional work is needed to reduce computing costs further. [less ▲]

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See detailPotential use of milk mid-infrared spectra to predict individual methane emission of dairy cows
Dehareng, Frédéric; Delfosse, Camille; Froidmont, Eric et al

in Animal (2012), 6(10), 1694-1701

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See detailUse of milk fatty acids to substitute for body condition score in breeding purposes
Bastin, Catherine ULg; Berry, D.P.; Soyeurt, Hélène ULg et al

in Journal of Dairy Science (2012), 95, Suppl. 2

Detailed reference viewed: 35 (9 ULg)