References of "Gengler, Nicolas"
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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 detailGenetic variance in environmental sensitivity for milk and milk quality in Walloon Holstein cattle
Vandenplas, Jérémie ULg; Bastin, Catherine ULg; Gengler, Nicolas ULg et al

in Book of Abstracts of the 63rd Annual Meeting of the European Federation of Animal Science (2012)

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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 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

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See detailGenome-wide association study for milk fatty acid composition using cow versus bull data
Bastin, Catherine ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg et al

in Book of Astracts of the 63rd Annual Meeting of the European Federation of Animal Science (2012)

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See detailGenetics of the mid-infrared predicted lactoferrin content in milk of dairy cows
Bastin, Catherine ULg; Leclercq, Gil ULg; Soyeurt, Hélène ULg et al

in Book of Astracts of the 63rd Annual Meeting of the European Federation of Animal Science (2012)

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See detailGenetics of the mid-infrared prediction of lactoferrin content in milk for Holstein first-parity cows
Bastin, Catherine ULg; Leclercq, Gil ULg; Soyeurt, Hélène ULg et al

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

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See detailAssessing heat stress effects on production traits of Holsteins in a temperate region
Hammami, Hedi ULg; Bormann, Jeanne; Gengler, Nicolas ULg

Conference (2012)

Heat stress impaired productive, reproductive and animal behaviour. Examination of milk production loss due to heat stress was mainly evaluated in USA and few tropical countries using the temperature ... [more ▼]

Heat stress impaired productive, reproductive and animal behaviour. Examination of milk production loss due to heat stress was mainly evaluated in USA and few tropical countries using the temperature humidity index (THI1) developed in the 1950’s. The main objective of this study was to evaluate the effects of six new environmental stress indices on production traits in a temperate region. These indices include solar radiation and wind speed in addition to the temperature and humidity only defining THI1. For that purpose, 530820 milk, fat, protein, and somatic cell count first-lactation test-day records (TD) collected between 2000 and 2011 in Luxembourg were used. TD records were merged with meteorological data from 14 public weather stations. Each TD was assigned to the average daily thermal index of the 3 days before. Firstly, broken-line regression models were applied to identify the threshold of heat stress (THR) for each of the thermal indices. The decline of daily production of the different traits above THR point was assessed by mixed linear models including regression on unit of each of the thermal index. Estimates of THR were specific to each thermal index and trait. Significant decrease of milk, fat and protein yields above THR was observed for all studied thermal predictors. Whereas, an increase of the somatic cell score was observed above the specific THR point. THR estimates for THI1 and THI6 were of 68 and 80 and 62 and 78 for milk and protein yields respectively. Respective rate of decline per unit were of 0.243 and 0.188 kg and 0.0045 and 0.0051 kg respectively. Results from this phenotypic analysis show that evaluating heat tolerance based on bio-meteorological indicators is promising and phenotypic and genetic implications should be investigated. [less ▲]

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See detailAssessing heat stress effects on production traits of Holsteins in a temperate region
Hammami, Hedi ULg; Bormann, Jeanne; Gengler, Nicolas ULg

in Book of abstracts of the 63rd Annual Meeting of the European Association for Animal Production (2012)

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See detailEstimation of genetic parameters for longitudinal measurements of feed intake in Piétrain sire lines
Dufrasne, Marie ULg; Jaspart, Véronique; Wavreille, José et al

in Book of Abstracts of the 63rd Annual Meeting of the European Association of Animal Science (2012)

Detailed reference viewed: 21 (7 ULg)