References of "Gengler, Nicolas"
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See detailGenetic parameters for individual birth weight, weaning weight and final weight of crossbred pigs from Piétrain boars
Dufrasne, Marie ULg; Wavreille, José; Piedboeuf, Maureen et al

Poster (2014, August)

Genetic parameters for birth weight (BWT), weaning weight (WWT), and final weight (BW) were estimated for crossbred pigs from Piétrain boars raised in test station. Estimates of direct heritability were ... [more ▼]

Genetic parameters for birth weight (BWT), weaning weight (WWT), and final weight (BW) were estimated for crossbred pigs from Piétrain boars raised in test station. Estimates of direct heritability were moderate (0.25 to 0.42), suggesting that genetic improvement of growth would be possible. Estimates of maternal heritability were 0.24 for BWT and WWT, and 0.05 for BW, indicating that the genetic influence of the dam on growth was not negligible until weaning. Genetic correlations between direct and maternal effects for BWT and WWT were moderate and unfavorable (-0.52 and -0.57 respectively). Direct genetic correlations were high and favorable between traits (0.40 to 0.75), suggesting that a high BWT is a good predictor to produce pigs with high final weight. Maternal genetic correlations between traits were low (0.01 to 0.03). Selection for higher BWT would increase final market weight but should be balanced with survival traits. [less ▲]

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See detailQuel système d'évaluations génétiques pour les verrats Piétrain en Wallonie
Dufrasne, Marie ULg; Piedboeuf, Maureen; Wavreille, José et al

Article for general public (2014)

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See detailStrategies to combine novel traits across countries: example of heat stress
Hammami, Hedi ULg; Vandenplas, Jérémie ULg; Carabaño, Maria Jesus et al

Conference (2014, May 21)

Nowadays, novel traits are of great interest. However, phenotypes are siloed and mainly not shared. Heat stress is becoming problematic affecting animals’ performances and their well-being. Heat stress ... [more ▼]

Nowadays, novel traits are of great interest. However, phenotypes are siloed and mainly not shared. Heat stress is becoming problematic affecting animals’ performances and their well-being. Heat stress tolerance as a novel trait is only addressed by isolated within-country research studies. Integration and combination of local and foreign information sources is needed for better accuracy genetic evaluations. Therefore, this study was aimed to test the potential combination of sources of external information towards the evaluation of heat stress tolerance of dairy cattle. Long-term cow performances linked to environmental descriptors (weather parameters as proxy to climate change) collected over 10 years under the temperate conditions of the Walloon Region of Belgium and the hotter and warm Mediterranean conditions of Andalusia and Castile-La-Mancha Spanish regions were available. A total of 1,604,775 milk, fat, and protein test-day (TD) records linked to average daily temperature humidity (THI) values for 3-day lag before each TD were considered. Under a first strategy considering free-access to raw-data (phenotype and pedigree), a joint evaluation was firstly run using reaction norm models where production traits were considered as function of THI. A Belgian and a Spanish evaluation were also run using the same model. An alternative strategy considering only access to external information (i.e. regression coefficients for additive genetic effects (â and their associated REL)) was tested. In this case, foreign â and their REL resulting from the Spanish evaluation were first converted to the Belgian trait and thereafter integrated in the Belgian evaluation using a Bayesian approach. Rank correlations between regression coefficients, â (of the 1,104 bulls having daughters only in Spain) estimated by Belgian evaluation and â estimated by the joint evaluation were moderate (<=0.70). Corresponding rank correlations between â estimated by joint and Bayesian evaluations were significantly higher (ranging from 0.967 to 0.998), indicating that the Bayesian evaluation integrating external information was in good concordance with the joint evaluation. Results from this study indicated that the integration of external information via the Bayesian approach has a good potential to improve the genetic evaluation of sparse and siloed novel traits. [less ▲]

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See detailContributions à l’amélioration des systèmes d’évaluations génétiques
Vanderick, Sylvie ULg; Gengler, Nicolas ULg

Conference given outside the academic context (2014)

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See detailPhenotypic and genetic variability of methane emissions and milk fatty acid contents of Walloon Holstein dairy cows
Vanrobays, Marie-Laure ULg; Kandel, Purna Bhadra ULg; Soyeurt, Hélène ULg et al

Poster (2014, February 17)

There is a growing interest in reducing methane (CH4) emissions from enteric fermentation of dairy cows because these emissions contribute to climate change and represent losses of gross energy intake for ... [more ▼]

There is a growing interest in reducing methane (CH4) emissions from enteric fermentation of dairy cows because these emissions contribute to climate change and represent losses of gross energy intake for cows. Milk fatty acid (FA) profile is influenced by rumen fermentations. The aim of this study was to estimate phenotypic and genetic variability of enteric CH4 emissions of dairy cows and FA contents of milk. CH4 emissions (g/d) and milk FA contents are predicted from milk mid-infrared (MIR) spectra based on calibration equations developed by Vanlierde et al. (2013) and Soyeurt et al. (2011), respectively. Data included 161,681 records from 22,642 cows in 489 herds. Genetic parameters of MIR CH4 emissions and 7 groups of FA contents in milk were estimated for Walloon Holstein cows in first parity using bivariate (CH4 emission with a FA trait) random regression test-day models. Saturated FA presented higher genetic correlations with MIR CH4 production than unsaturated FA (0.25 vs. 0.10). Genetic correlations with MIR CH4 emissions were higher for short- (SC) and medium-chain (MC) FA (0.24 and 0.23, respectively) than for long-chain (LC) FA (0.13). Phenotypic correlations between MIR CH4 emissions and SC and MC FA were also higher than those between MIR CH4 emissions and LC FA (0.20 vs. -0.08). Finally, results showed that MIR milk FA profile and MIR CH4 emissions are correlated emphasizing indirect link between milk FA and CH4 emissions through rumen metabolism. [less ▲]

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See detailEstimating daily yield and content of major fatty acids from single milking
Arnould, Valérie ULg; Reding, Romain; Delvaux, Charles et al

Poster (2014, February 07)

Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of official milk recording. However, fewer samples lead to a decrease ... [more ▼]

Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of official milk recording. However, fewer samples lead to a decrease in the accuracy of predicted daily yields. Unfortunately, the current published equations use the milking interval that is often not available and/or reliable in practice. The first objective of this study was to propose models using easily available traits. Therefore the milking interval was replaced by a combination of data easily recorded by milk recording. The second objective of this study was to enlarge the previous investigations to milk fatty acids (FA) in order to propose a practical method for estimating accurate daily milk, fat and major FA yields from single milking. The fit goodness of proposed models was evaluated based on the correlation values between the estimated and observed daily yields in addition to the calculation of the mean square error. Obtained results are promising. Correlation values were comprised between 96.4% and 97.6% when daily yield were estimated from morning milking, and from 96.9% to 98.3% when daily yield were estimated from evening milking. The combination of records related to lactation stage, month of test, milk yield, and fat could replace the milking interval effect. Because of their simplicity, proposed models would be easy to implement. [less ▲]

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See detailConsequences of Selection for Environmental Impact Trait in Dairy Cows
Kandel, Purna Bhadra ULg; Vanderick, Sylvie ULg; Vanrobays, Marie-Laure ULg et al

Scientific conference (2014, February 07)

Environmental sustainability is gaining importance in dairy industry due to enteric methane (CH4) emission from dairy cows. We predicted CH4 indicator trait (CH4 intensity: CH4 g/kg of milk) from Mid ... [more ▼]

Environmental sustainability is gaining importance in dairy industry due to enteric methane (CH4) emission from dairy cows. We predicted CH4 indicator trait (CH4 intensity: CH4 g/kg of milk) from Mid-infrared spectra of milk samples and recorded milk yield. Genetic correlations between CH4 intensity and milk production traits were estimated on Holstein cows from correlations of estimated breeding values. Genetic correlations between CH4 intensity and milk yield (MY) was -0.67, fat yield (FY) -0.13, protein yield (PY) -0.46, somatic cell score (SCS) 0.02, longevity -0.07, fertility 0.31, body condition score (BCS) 0.27 and average of confirmation traits -0.23. Currently, there is no CH4 emission trait in genetic evaluation selection index. Putting an hypothetical 25% weight on CH4 intensity on current Walloon genetic evaluation selection index and proportional reduction on other selection traits, the response to selection will be reduction of CH4 emission intensity by 24%, increase in MY by 30%, FY by 17%, PY by 29%, SCS by -15%, longevity by 24%, fertility by -11%, BCS by -13% and conformation traits by 24%. In conclusion, introduction of environmental traits in current selection index will affect selection responses. As there is no economic value of these traits presently alternative methods like putting correlated traits with clear economic value (e.g. feed efficiency) in the selection objective could generate appropriate index weights. [less ▲]

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See detailEfficient computation of genomically-enhanced inbreeding coefficients
Faux, Pierre ULg; Gengler, Nicolas ULg

Poster (2014, February 07)

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See detailStrategies to Combine Novel Traits across Countries: Example of Heat Stress
Hammami, Hedi ULg; Vandenplas, Jérémie ULg; Carabaño, Maria-Jesus et al

in Interbull Bulletin (2014), 48

Nowadays, novel traits are of great interest. However, phenotypes are siloed and mainly not shared. Heat stress is becoming problematic affecting animals’ performances and their well-being. Heat stress ... [more ▼]

Nowadays, novel traits are of great interest. However, phenotypes are siloed and mainly not shared. Heat stress is becoming problematic affecting animals’ performances and their well-being. Heat stress tolerance as a novel trait is only addressed by isolated within-country research studies. Integration and combination of local and foreign information sources is needed for better accuracy genetic evaluations. Therefore, this study was aimed to test the potential combination of sources of external information towards the evaluation of heat stress tolerance of dairy cattle. Long-term cow performances linked to environmental descriptors (weather parameters as proxy to climate change) collected over 10 years under the temperate conditions of the Walloon Region of Belgium and the hotter and warm Mediterranean conditions of Andalusia and Castile-La-Mancha Spanish regions were available. A total of 1,604,775 milk, fat, and protein test-day (TD) records linked to average daily temperature humidity (THI) values for 3-day lag before each TD were considered. Under a first strategy considering free-access to raw-data (phenotype and pedigree), a joint evaluation was firstly run using reaction norm models where production traits were considered as function of THI. A Belgian and a Spanish evaluation were also run using the same model. An alternative strategy considering only access to external information (i.e. regression coefficients for additive genetic effects (â and their associated REL)) was tested. In this case, foreign â and their REL resulting from the Spanish evaluation were first converted to the Belgian trait and thereafter integrated in the Belgian evaluation using a Bayesian approach. Rank correlations between regression coefficients, â (of the 1,104 bulls having daughters only in Spain) estimated by Belgian evaluation and â estimated by the joint evaluation were moderate (<=0.70). Corresponding rank correlations between â estimated by joint and Bayesian evaluations were significantly higher (ranging from 0.967 to 0.998), indicating that the Bayesian evaluation integrating external information was in good concordance with the joint evaluation. Results from this study indicated that the integration of external information via the Bayesian approach has a good potential to improve the genetic evaluation of sparse and siloed novel traits. [less ▲]

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See detailStrategies to combine novel traits across countries: example of heat stress
Hammami, Hedi ULg; Vandenplas, Jérémie ULg; Carabaño, Maria Jesus et al

in Interbull Bulletin (2014), 48

Nowadays, novel traits are of great interest. However, phenotypes are siloed and mainly not shared. Heat stress is becoming problematic affecting animals’ performances and their well-being. Heat stress ... [more ▼]

Nowadays, novel traits are of great interest. However, phenotypes are siloed and mainly not shared. Heat stress is becoming problematic affecting animals’ performances and their well-being. Heat stress tolerance as a novel trait is only addressed by isolated within-country research studies. Integration and combination of local and foreign information sources is needed for better accuracy genetic evaluations. Therefore, this study was aimed to test the potential combination of sources of external information towards the evaluation of heat stress tolerance of dairy cattle. Long-term cow performances linked to environmental descriptors (weather parameters as proxy to climate change) collected over 10 years under the temperate conditions of the Walloon Region of Belgium and the hotter and warm Mediterranean conditions of Andalusia and Castile-La-Mancha Spanish regions were available. A total of 1,604,775 milk, fat, and protein test-day (TD) records linked to average daily temperature humidity (THI) values for 3-day lag before each TD were considered. Under a first strategy considering free-access to raw-data (phenotype and pedigree), a joint evaluation was firstly run using reaction norm models where production traits were considered as function of THI. A Belgian and a Spanish evaluation were also run using the same model. An alternative strategy considering only access to external information (i.e. regression coefficients for additive genetic effects (â and their associated REL)) was tested. In this case, foreign â and their REL resulting from the Spanish evaluation were first converted to the Belgian trait and thereafter integrated in the Belgian evaluation using a Bayesian approach. Rank correlations between regression coefficients, â (of the 1,104 bulls having daughters only in Spain) estimated by Belgian evaluation and â estimated by the joint evaluation were moderate (<=0.70). Corresponding rank correlations between â estimated by joint and Bayesian evaluations were significantly higher (ranging from 0.967 to 0.998), indicating that the Bayesian evaluation integrating external information was in good concordance with the joint evaluation. Results from this study indicated that the integration of external information via the Bayesian approach has a good potential to improve the genetic evaluation of sparse and siloed novel traits. [less ▲]

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See detailImpact of Heat Stress on Production in Holstein Cattle in four EU Regions. Selection Tools
Carabaño, Maria-Jesus; Hammami, Hedi ULg; Logar, Betka et al

Scientific conference (2014)

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See detailImpact of Heat Stress on Production in Holstein Cattle in four EU Regions. Selection Tools
Carabaño, Maria-Jesus; Hammami, Hedi ULg; Logar, Betka et al

Conference (2014)

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See detailGenotype x Climate interactions for protein yield using four European Holstein Populations
Hammami, Hedi ULg; Carabaño, Maria-Jesus; Logar, Betka et al

Conference (2014)

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See detailPotential for assessing the pregnancy status of dairy cows by mid-infrared analysis of milk
Laine, Aurélie ULg; Bel Mabrouk, Hana ULg; Dale, Laura-Monica ULg et al

in Book of Abstracts of the 65th Annual Meeting of the European Federation of Animal Science (2014)

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See detailNon-genetic sources of variation of milk production and reproduction and interactions between both classes of traits in Sicilo-Sarde dairy sheep.
Merai, A.; Gengler, Nicolas ULg; Hammami, Hedi ULg et al

in Animal (2014), 8(9), 1534-9

This work aimed to study the sources of variation in productive and reproductive traits of the dairy Sicilo-Sarde ewes and to further investigate the interaction between both classes of traits. After ... [more ▼]

This work aimed to study the sources of variation in productive and reproductive traits of the dairy Sicilo-Sarde ewes and to further investigate the interaction between both classes of traits. After edits, a database containing 5935 lactation records collected during 6 successive years in eight dairy flocks in the North of Tunisia was used. Total milked milk (TMM) in the milking-only period was retained as productive trait. The interval from the start of the mating period to the subsequent lambing (IML) and the lambing status (LS) were designed as reproductive traits. Sicilo-Sarde ewes had an average TMM of 60.93 l (+/-44.12) during 132.8 days (+/-46.6) after a suckling period of 100.4 days (+/-24.9). Average IML was 165.7 days. In a first step, the major factors influencing milk production and reproductive traits were determined. The significant sources of variation identified for TMM were: flock, month of lambing, year of lambing, parity, suckling length, litter size and milking-only length. Flockxmonth of the start of the mating period, parity, year of mating and litter size were identified as significant factors of variation for IML, while flockxmonth of the start of the mating period, parity and year of mating were identified as significant sources of variation for LS. In a second step, variance components were estimated using a three traits threshold mixed model, which combined LS as categorical trait and TMM and IML as continuous traits. Repeatability estimates were 0.21 (+/-0.03) for TMM, 0.09 (+/-0.02) for IML, and 0.10 (+/-0.05) for LS. Moreover, TMM and IML were found to be favorably associated for the flockx year of lambing effect (-0.45+/-0.18) but unfavorably associated for the animal effect (0.20+/-0.09). [less ▲]

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See detailA review of inversion techniques related to the use of relationship matrices in animal breeding
Faux, Pierre ULg; Gengler, Nicolas ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(3), 319-468

In animal breeding, prediction of genetic effects is usually obtained through the use of mixed models. For any of these genetic effects, mixed models require the inversion of the covariance matrix ... [more ▼]

In animal breeding, prediction of genetic effects is usually obtained through the use of mixed models. For any of these genetic effects, mixed models require the inversion of the covariance matrix associated to that effect, which is equal to the associated relationship matrix times the associated component of the genetic variance. Given the size of many genetic evaluation systems, computing the inverses of these relationship matrices is not trivial. In this review, we aim to cover computational techniques that ease inversion of relationship matrices used in animal breeding for prediction of the following different types of genetic effects: additive effect, gametic effect, effect due to presence of marked quantitative trait loci, dominance effect and different epistasis effects. Construction rules and inversion algorithms are detailed for each relationship matrix. In the final discussion, we draw up a common theoretical frame to most of the reviewed techniques. Two computational constraints come out of this theoretical frame: setting up the matrix of dependencies between levels of the effect and setting up some parts (diagonal or block-diagonal elements) of the relationship matrix to be inverted. [less ▲]

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