References of "Gengler, Nicolas"
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See detailLinking first lactation survival to milk yield and components and lactation persistency in Tunisian Holstein cows
Grayaa, Marwa ULiege; Vanderick, Sylvie ULiege; Rekik, Boulbaba et al

in Archiv für Tierzucht (2019), 65(1), 153160

Genetic parameters were estimated for first lactation survival defined as a binary trait (alive or dead to second calving) and the curve shape traits of milk yield, fat and protein percentages using ... [more ▼]

Genetic parameters were estimated for first lactation survival defined as a binary trait (alive or dead to second calving) and the curve shape traits of milk yield, fat and protein percentages using information from 25 981 primiparous Tunisian Holsteins. For each trait, shape curves (i.e. peak lactation, persistency), level of production adjusted to 305 days in milk (DIMs) for total milk yield (TMY), and average fat (TF %) and protein (TP %) percentages were defined. Variance components were estimated with a linear random regression model under three bivariate animal models. Production traits were modelled by fixed herd × test-day (TD) interaction effects, fixed classes of 25 DIMs × age of calving × season of calving interaction effects, fixed classes of pregnancy, random environment effects and random additive genetic effects. Survival was modelled by fixed herd × year of calving interaction effects and age of calving × season of calving interaction effects, random permanent environment effects, and random additive genetic effects. Heritability (h2) estimates were 0.03 (±0.01) for survival and 0.23 (±0.01), 0.31 (±0.01) and 0.31 (±0.01) for TMY, TF % and TP %, respectively. Genetic correlations between survival and TMY, TF % and TP % were 0.26 (±0.08), −0.24 (±0.06) and −0.13 (±0.06), respectively. Genetic correlations between survival and persistency for fat and protein percentages were −0.35 (±0.09) and −0.19 (±0.09), respectively. Cows that had higher persistencies for fat and protein percentages were more likely not to survive. [less ▲]

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See detailRôle de la transmission des maladies dans le déclin des pollinisateurs – Synthèse bibliographique
Noël, Grégoire ULiege; Bebermans, Julien ULiege; Gengler, Nicolas ULiege et al

in Entomologie Faunistique (2018), 71

L’appauvrissement de la biodiversité globale est devenu une préoccupation croissante pour notre société. Ce déclin, d’origine multifactorielle, de la diversité des organismes touche également la ... [more ▼]

L’appauvrissement de la biodiversité globale est devenu une préoccupation croissante pour notre société. Ce déclin, d’origine multifactorielle, de la diversité des organismes touche également la communauté des pollinisateurs qui assure la reproduction des plantes. Les pollinisateurs fournissent aussi un excellent service écosystémique à l'humanité, en particulier pour la sécurité alimentaire et le bien-être humain. La transmission de maladies intra- et interspécifique des pollinisateurs est un des facteurs du déclin de plus en plus étudié. L'objectif de cette revue est d’offrir une mise à jour des causes principales du déclin en se concentrant particulièrement sur l’impact de la transmission des maladies. Outre les effets synergiques de la dégradation du paysage, des pesticides, des changements climatiques et d’espèces invasives, une relation existe entre l’introduction de pollinisateurs domestiques dans de nouveaux milieux et l’émergence de nouvelles maladies. Via la globalisation des échanges commerciaux, certains agents pathogènes sont devenus des menaces importantes concernant la santé des pollinisateurs. Cependant, il subsiste encore des lacunes importantes dans la connaissance des mécanismes de transmission. Des avancées scientifiques et technologiques dans ce domaine permettraient aux autorités d’établir une réglementation sanitaire plus adaptée et ainsi contribuer à la sauvegarde à l’ensemble de la communauté des pollinisateurs. [less ▲]

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See detailBioassays to quantify hygienic behavior in honey bee (Apis mellifera L.) colonies: a review
Leclercq, Gil; Francis, Frédéric ULiege; Gengler, Nicolas ULiege et al

in Journal of Apicultural Research (2018), 57(5), 663-673

Individual immunity in honey bees (Apis mellifera L.) is complemented by highly evolved social behaviors. Among them, hygienic behavior has a key role involving the detection and removal of unhealthy or ... [more ▼]

Individual immunity in honey bees (Apis mellifera L.) is complemented by highly evolved social behaviors. Among them, hygienic behavior has a key role involving the detection and removal of unhealthy or dead brood. Since the 1960s, several bioassays have been developed to quantify the hygienic behavior of honey bee colonies against chalkbrood, American foulbrood, and varroa infested brood. Here, we review the five main bioassays used since the late 1960s. We describe their advantages and disadvantages, including a special focus on their inherent biases. For each assay, we also discuss whether or not their use should be restricted to quantify the hygienic behavior against chalkbrood, or American foulbrood, or varroa infested brood. Overall, the bioassays involving the removal of freeze-killed brood are recommended over the bioassays relying on the removal of pin-killed brood but only for the quantification of hygienic behavior toward chalkbrood and American foulbrood. These bioassays are not recommended to quantify the hygienic behavior toward varroa infested brood, for which an accurate assessment should rely on assays based on the removal of brood artificially infested with varroa mites. Choosing an appropriate bioassay is crucial for an accurate assessment of the hygienic behavior against a defined pathogen, depending on the research question, or the goal of the breeding program. [less ▲]

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See detailCH4 emitted by dairy cows estimated from milk MIR spectra: model based on data collected in 7 countries
Vanlierde, Amélie ULiege; Dehareng, Frédéric; Gengler, Nicolas ULiege et al

in International Conference on Agricultural GHG Emissions and Food Security – Connecting research to policy and practice – Volume of Abstracts (2018, September)

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See detailTemporal relationship between milk MIR predicted metabolic disorders and lameness events
Mineur, Axelle ULiege; Vanderick, Sylvie ULiege; Hammami, Hedi ULiege et al

in Book of Abstracts of the 68th Annual Meeting of the European Federation of Animal Science (2018, August 27)

Lameness is an often occurring consequence of various metabolic disorders, such as sub-acute ruminal acidosis (SARA) or ketosis. Recent research showed that these metabolic disorders can be predicted with ... [more ▼]

Lameness is an often occurring consequence of various metabolic disorders, such as sub-acute ruminal acidosis (SARA) or ketosis. Recent research showed that these metabolic disorders can be predicted with reasonable accuracy with mid-infrared (MIR) spectral data. In order to study the potentially complex temporal relationship between MIR predicted metabolic disorders and lameness events over the course of the lactation, data from 3895 cows on 122 farms, representing the Simmental, Brown-Swiss and Holstein breeds. A total of 38316 lameness and 11419 MIR records were collected over a period from July to December 2014 through the Efficient Cow Project. Lactations were subdivided into 30 days lactation stage classes. Milk MIR predicted metabolites such as ketone bodies, acetone, citrates and fatty acids (C18:1cis9), and lameness scores were averaged over animals and these classes. In order to assess the temporal link between occurrences of metabolic disorder and lameness events, correlations were computed between averaged metabolites and lameness scores across the lactation stage classes. Correlations tended to be higher when comparing predicted metabolites with lameness in the three following months, rather than the same one. Results showed differences between breeds, Simmentals showing lower correlations than Holsteins or Brown-Swiss. Especially very early values for milk MIR predicted metabolites (first month), and therefore suspected metabolic disorders, were correlated more strongly to later occurring lameness events in Brown Swiss. In Holsteins, higher correlation between metabolites and lameness were observed during later lactation. In general, given the use of classes, the correlations tended to be unstable. Alternative methods, such as covariance functions, might therefore be useful to get a clearer picture. However these first results seem to support the idea of temporal relationships between metabolic disorders and later lameness events during the lactation. [less ▲]

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See detailCH4 estimated from milk MIR spectra: model on data from 7 countries and 2 measurement techniques
Vanlierde, Amélie ULiege; Dehareng, Frédéric; Gengler, Nicolas ULiege et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Availability of a robust proxy to estimate individual daily methane (CH4) emissions from dairy cows would be valuable especially for large scale studies, for instance with genetic purpose. Milk mid ... [more ▼]

Availability of a robust proxy to estimate individual daily methane (CH4) emissions from dairy cows would be valuable especially for large scale studies, for instance with genetic purpose. Milk mid infrared (MIR) spectroscopy presents potential to meet this aim as spectra can be obtained routinely at reasonable cost through milk recording process. Development of a prediction equation requires as much variability as possible in the reference data set to improve the accuracy and ensure the robustness of the model. So, two datasets including CH4 measurements and corresponding milk MIR spectra have been merged: the first contained 532 data from 156 cows of Ireland and Belgium with CH4 measurements obtained with SF6 tracer technique; the second reached 584 data from 147 cows of Switzerland, United Kingdom, France, Denmark and Germany with CH4 measurements obtained with respiration chambers. In addition to the Partial Least Squares (PLS) equation using the raw CH4 values, a second equation was performed with a reduction of 8% to CH4 values from chambers to evaluate the need to correct the potential method bias in accordance with literature. A 5-group cross-validation was performed to test the robustness of the models. R2 and the standard error of cross-validation were 0.63 and 62 g/day from raw data and 0.65 and 59 g/day when CH4 respiration chamber values were adjusted. This slight improvement due to the adjustment of chamber measurement does not permit to conclude that this correction is needed. The study of residuals showed a non-significant effect due to the CH4 measurement technique. In conclusion this new equation combining CH4 from 2 different techniques covered more variability (cows, diets and country specific information) and shows potential as a proxy especially for genetic evaluation. [less ▲]

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See detailPrediction of test-day body weight from dairy cow characteristics and milk spectra
Soyeurt, Hélène ULiege; Colinet, Frédéric ULiege; Froidmont, E. et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

The knowledge of individual body weight (BW) is a management key in terms of feed efficiency and to assess the environmental footprint of dairy production. From 6 farms, BW were measured on 735 Holstein ... [more ▼]

The knowledge of individual body weight (BW) is a management key in terms of feed efficiency and to assess the environmental footprint of dairy production. From 6 farms, BW were measured on 735 Holstein cows. Daily milk samples were collected on these weighed cows and analysed by mid-infrared spectrometry. The stage and number of lactation were also collated. A spectral cleaning was conducted by calculating GH distances from 17 principal components. Spectra with a GH greater than 3 were discarded. The final dataset contained 720 records. Predicting equations were based on Partial Least Squares regressions. Cross-validation coefficient of determination (R2cv) and root mean square error (RMSEPcv) of the equation including only spectral data were of 0.19 and 65 kg. Then, days in milk, month of test and lactation stage were added. The obtained R2cv and RMSEPcv increased (0.43 and 54 kg). The part of the information derived from the spectral data was equal to 6%. By adding the daily milk yield, the BW prediction was slightly improved and showed a R2cv of 0.45 and a RMSEPcv of 53 kg. The use of Legendre Polynomials to regress the spectral data following the day in milk did not improve the predictability. By deleting samples showing a squared residual higher than its mean + 3 times of its standard deviation, the final equation included 668 samples (93% of the initial set) and had a R2cv of 0.58 and RMSEPcv of 42 kg. A herd cross-validation was then performed to assess the robustness of the developed equation. RMSEPv ranged from 40 to 58 kg. This preliminary study showed the potentiality to predict an indicator of body weight. As this prediction uses easy to record explicative variables and if a larger validation confirmed the obtained results, this prediction equation could be used to develop large scale study about feed efficiency. Moreover, this method allows to consider the past information if spectral data are available. [less ▲]

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See detailHow fast can we change resilience and efficiency through breeding and management?
Gengler, Nicolas ULiege; Hostens, M.

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

The efficiency of dairy cattle has to be balanced against their resilience to disease challenges but also their individual responses to internal and external environmental stressors. A holistic approach ... [more ▼]

The efficiency of dairy cattle has to be balanced against their resilience to disease challenges but also their individual responses to internal and external environmental stressors. A holistic approach is required as both efficiency and resilience have to be defined in a broad sense. Efficiency is more then only productive efficiency, the dilution of maintenance and indirect cost effects have to be considered through reduced feed, rearing, health and replacement costs; environmental costs should also not be forgotten. With this broader definition of efficiency, resilience as a major factor to reduce health costs contributes directly to a holistic view on efficiency. An underlying issue is here the old question if we change environments to address the needs of animals, or do we change animals to adapt to the environment. Previously, it was common understanding to prioritize first approach. However changing profoundly and suddenly environments and therefore management practices is difficult, disruptive and costly. However the EU FP7 project GplusE develops Hazard Analysis Critical Control Point (HACCP) and Evolutionary Operation (EVOP) based methods to optimize dairy cow management in a given production circumstance. The important advantage of this approach is that it is not disruptive but allows a slow but continued process of optimization. It is therefore not very different from the continuous process of cumulative optimization of the animals achieved by genomic selection, another important research topic of the GplusE project. Both approaches are complementary optimization opportunities for resilience and efficiency. However they are not possible without the development of appropriate response variables describing efficiency and resilience. The GplusE project has made the choice to develop novel milk based bio-markers and proxies for, often difficult to obtain; traits describing efficiency and resilience. Changes through breeding or management have to be continuous and well balanced considering the whole system. Changing environments or animals too fast should be avoided as this may lead to unforeseen consequences [less ▲]

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See detailEarly-programming of dairy cattle, a potential explanation to the adaptation to climate change
Hammami, Hedi ULiege; Colinet, Frédéric ULiege; Bastin, Catherine et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Breeding for robustness and considering genotype by environment interaction (G×E) is linked to adaptation. Recently, it has been established that gene expression can be affected by the environment during ... [more ▼]

Breeding for robustness and considering genotype by environment interaction (G×E) is linked to adaptation. Recently, it has been established that gene expression can be affected by the environment during the embryo development. The concept of early programming has been demonstrated in many settings. This study aimed to assess the impact of thermal stress when dairy cows been conceived on their lifetime performances. Studied traits were milk yield and some novel milk-based biomarkers, fertility (days open), health (somatic cell score and ketosis), and heat tolerance. Data used compromised 905,391 test day of 58,297 cows in parity 1 to 3 for production traits, health and ketosis status, 104,635 records of 48,125 cows for days open, and 399,449 test days recorded (linked with temperature humidity index values, THI) of 28,203 cows for heat tolerance trait. Date of conception was estimated using the next calving date of the cow and subtracting 280 d from the calving interval. Cows being conceived in summer (June- August) were considered as influenced by heat stress (environment 1) and those conceived in winter (December- February) as neutral-thermal conditions (environment 2). G×E was analysed by a multi-trait model for days open in which each of the 3 lactations measured in heat stress and thermo-neutral conditions were considered as separate traits. For the rest of the traits, it was analysed using reaction norm models, in which the trait is considered a function of an environmental descriptor (i.e. THI, days in milk) in the two discrete environments. First results showed that genetic correlations across both early-life defined environments and lactations were substantially lower than unity, implying that effects of genes for cows conceived under neutral-thermal conditions may be different of the effects for the same genes for cows conceived under heat stressed conditions. [less ▲]

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See detailTheoretical basis to extend single-step genomic prediction of dominance in a pig population
REIS MOTA, Rodrigo ULiege; Vanderick, Sylvie ULiege; Colinet, Frédéric ULiege et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Single-step methods predict implicitly unknown gene content information of non-genotyped from known gene content for genotyped animals. This theory is well derived in an additive setting. There are ... [more ▼]

Single-step methods predict implicitly unknown gene content information of non-genotyped from known gene content for genotyped animals. This theory is well derived in an additive setting. There are reasons not to ignore the dominance context when working with partially genotyped populations. This study addressed several outstanding issues in this context. First, it presented the theoretical basis for dominance single-step genomic best linear unbiased prediction theory. A specific and important issue in all dominance setting is the handling of inbreeding. A total of five dominance single-step inverse matrices were tested and described as C1 to C5 by considering different parameterization (e.g. different ways to account for inbreeding) for pedigree-based and genomic relationships matrices. We simulated genotypes for real crossbred pig population (n=11,943 animals). The SNP effects were assumed to be equal to calculate true dominance values. We added random noise and used them as phenotypes. Accuracy was defined as correlation between true and predicted dominance breeding values. We applied five replicates and estimated accuracies between three situations: all (S1); non-genotyped (S2) and inbred non-genotyped animals (S3). Potential bias of predicted dominance values was assessed by regressing the true dominance values on predicted values. Accuracies of each tested matrix (C1 to C5) were 0.75, 0.33 and 0.35 in average, for S1, S2 and S3, respectively. The matrix C5 better performed and breeding values from C1 and C2 were more biased than those obtained by using C3, C4 and C5. We showed a useful approach to predict dominance gene contents for nongenotyped from genotyped animals. Better matrix compatibility can be obtained by re-scaling the pedigree-based and the genomic relationship matrices to obtain standardized diagonal elements equal to 1 minus the inbreeding coefficient, i.e. the C5 matrix. [less ▲]

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See detailMulti-omics data integration approach for resilience of dairy cattle to heat stress
Hammami, Hedi ULiege; Colinet, Frédéric ULiege; Bastin, Catherine et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Breeding for resilience to heat stress (HS) is a topic where associating multiple omics data has the potential to get a better view of the issues and to allow significant advances to overcome undesirable ... [more ▼]

Breeding for resilience to heat stress (HS) is a topic where associating multiple omics data has the potential to get a better view of the issues and to allow significant advances to overcome undesirable consequences of future extreme weather scenarios. An example of omics is here epigenomics (e.g. early programming due to heat-stress) allowing new insights to explain biological mechanisms of resilience to HS and G×E interactions. Even if biological mechanisms are complex and still elusive, this study tried to use a holistic approach integrating milk-based biomarkers, climate conditions, and genomics. Data used included 65,907 third-lactation test-day records for production traits (milk, fat and protein yields), specific fatty acids (FA) and metabolites predicted from mid-infrared spectra (C4:0, C18:1cis9, long chain ‘LCFA’, mono- and unsaturated FA ‘MUFA and UFA’, acetone and BHB) of 9,327 Holstein cows. Phenotypes were merged with a temperature humidity index (THI) from public weather stations. For each trait, the response to THI was estimated via days in milk (DIM) × THI combination, and for each cow by using a random regression model with a common threshold of THI=62. The slope (heat tolerance)-to-intercept (general) genetic variance ratios increased as THI increased. They were higher during mid-lactation (140-245 DIM) for C18:1 cis9, acetone, BHB and for production traits, whereas higher in early lactation (≤125 DIM) for C4:0, LCFA, MUFA, and UFA. At extreme high THI scale, slope-to-intercept ratios for C18:1 cis9, MUFA, UFA, and LCFA were 3.8, 3.4, 3.1, 2.8 fold higher than milk yield. These findings indicate that tolerance to HS and traditional production trait responses to THI are marginally related, and changes in milk-based biomarkers under high THI better elucidate physiological and metabolic pathways in HS dairy cows. Ongoing genomic wide association studies will better explain genetic markers unravelling the biological background of resilience to HS. [less ▲]

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See detailIdeas for continuous genomic evaluation for newly genotyped Walloon Holstein females and males
Naderi Darbaghshahi, Saeid ULiege; REIS MOTA, Rodrigo ULiege; Vanderick, Sylvie ULiege et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Crucial for large scale use in dairy cattle of genotyping for females is that any newly genotyped animal (calves, cows and heifers but also bulls) receives very quickly genomic breeding values (GEBV) even ... [more ▼]

Crucial for large scale use in dairy cattle of genotyping for females is that any newly genotyped animal (calves, cows and heifers but also bulls) receives very quickly genomic breeding values (GEBV) even outside the official schedule for routine evaluations. In this study, a system was developed to estimate initial GEBV for newly genotyped animals before their inclusion in the official routine release of genomic evaluations. The system was setup to be run on request, featuring the setup of a ‘continuous’ evaluation, also being quick and simple enough to be used at least on a weekly base. For animals without own records or descendants, official GEBV were approximated using selection-index like method by combining direct genomic values (DGV) of newly genotyped animals and their parent average (PA). DGV for new genotyped animals were calculated based on SNP effects from the previous official routine evaluations (April and August, 2017). Depending on GEBV accessibility from parents of a given animal, PA was calculated based on conventional phenotypic information (cPA), and parent GEBV (gPA). To expand the system for animals with progeny, a subset of genotyped animals was selected, and conventional estimated breeding values (cEBV) and cPA of selected animals were combined with DGV and gPA in order to obtain GEBV for animals with progeny. The weights were calculated based on the covariance between DGV and gPA for animals without progeny, and between DGV, gPA, cEBV and cPA for animals with progeny. Correlations between initial and April official evaluations for 60 new genotyped animals without progeny varied from 0.87 to 0.95 for conformation, fertility and production traits, whereas correlations between initial and August official evaluations varied 0.84 to 0.92 (n=25 new genotyped animals). On the other hand, correlations between initial and August official evaluations for 120 genotyped animals with progeny varied from 0.95 to 0.97 for production traits. Study showed potential to use simple selection index based methods in continuous genomic evaluations, a way to support genotyping of females for genomic selection but also for management and marketing. [less ▲]

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See detailPrediction of milk mid-infrared spectrum using mixed test-day models
Delhez, Pauline ULiege; Vanderick, Sylvie ULiege; Colinet, Frédéric ULiege et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Mid-infrared (MIR) analysis of milk currently allows the measurement of many variables of interest for the dairy sector related to milk nutritional quality, milk technological properties, cow’s status or ... [more ▼]

Mid-infrared (MIR) analysis of milk currently allows the measurement of many variables of interest for the dairy sector related to milk nutritional quality, milk technological properties, cow’s status or environmental fingerprint. The aim of this study was to explore the ability of a test-day model to predict milk MIR spectra, and therefore all the resultant variables, for a future test day of a known cow or for a new cow based on easily known characteristics of cows. This is useful for instance for herd management (e.g. detecting problems, predicting potential of heifers) or to predict future environmental impacts of a dairy herd. A total of 467,496 milk MIR spectra from 53,781 Holstein cows in first lactation were used for the calibration data set. First, 323 wavelengths out of the 1,060 wavelengths of the milk spectra were conserved. This spectral information was reduced by using principal component analysis (PCA). A total of 8 principal components (PC) were kept, representing 99% of the spectral information. Then 8 univariate test-day models including the day in milk, herd×year and herd×month as fixed effects and herd×test date, permanent environment and genetics as random effects were applied for each PC. From the solutions of the models and by using a back reversing operation using eigenvectors of the PCA, the predicted 323 wavelengths of the spectra were re-obtained. The calibration correlations between observed and predicted spectral data ranged from 0.76 to 0.93. Correlations between observed and predicted milk fat and protein contents obtained from the modelled spectra were 0.83 and 0.89, respectively. These findings demonstrate the moderate ability of a test-day model to predict milk MIR spectra. [less ▲]

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See detailEffect of milk yield and milk content curve shapes on first lactation survival in large herds
Grayaa, Marwa ULiege; Ben Gara, A.; Grayaa, S. et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

Genetic parameters of first lactation survival and curve shape traits of milk yield, fat and protein percentages were estimated using information of 25,981 primiparous Tunisian Holsteins belonging to ... [more ▼]

Genetic parameters of first lactation survival and curve shape traits of milk yield, fat and protein percentages were estimated using information of 25,981 primiparous Tunisian Holsteins belonging to large herds. For each trait lactation peak, apparent persistency, real persistency and level of production adjusted to 305 days in milk were defined. Variance components were estimated under three bivariate animal models with a linear random regression model. Milk yield as well as fat and protein percentages were modelled by fixed herd × test day interaction effects, fixed classes of 25 days in milk × age of calving × season of calving interaction effects, random environment effects, and random additive genetic effects. Survival was modelled by fixed herd × year of calving interaction effects, age of calving × season of calving interaction effects, random environment permanent effects, and random additive genetic effects. Heritability estimates were 0.03 for survival, 0.23, 0.29 and 0.30 for average milk yield, fat and protein percentages adjusted to 305 days in milk, respectively. Genetic correlations between survival and average milk yield, fat and protein percentages adjusted to 305 days in milk were 0.33, -0.33 and -0.14, respectively. Genetic correlations between survival and real persistency for fat and protein percentages were -0.24 and -0.15, respectively. Cows that had higher persistencies for fat and protein percentages, and therefore flatter fat and protein percentages curves, were more likely not to survive. This was due to higher fat percentages at the end of the lactation leading to the hypothesis that cows producing higher fat percentage dispose of less energy available for gestation and were therefore less likely to be or remain pregnant and, therefore, to survive. [less ▲]

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See detailGenetic parameters of novel mid-infrared predicted milk traits in three dual-purpose cattle breeds
Vanderick, Sylvie ULiege; Colinet, Frédéric ULiege; Mineur, Axelle ULiege et al

in Book of Abstracts of the 69th Annual Meeting of the European Federation of Animal Science (2018, August)

The objective of this study was to estimate genetic parameters of 39 novel mid-infrared predicted milk traits (e.g. nutritional quality, technological properties, metabolic status, environmental ... [more ▼]

The objective of this study was to estimate genetic parameters of 39 novel mid-infrared predicted milk traits (e.g. nutritional quality, technological properties, metabolic status, environmental fingerprint) for three dual purpose cattle breeds (i.e. Dual-Purpose Belgian Blue (dpBB), Montbéliarde (MON) and Normande (NOR)), which are also used in organic farming in the Walloon Region of Belgium, as part of the 2-Org-Cows project. Edited data included 21,287, 10,062 and 4,637 first-lactation test-day records collected in the Walloon region of Belgium from 2,988, 1,330 and 621 dpBB, MON and NOR cows, respectively. Genetic parameters were estimated using REML applied to single-trait random regression test-day models for six conventional traits (yields, contents and somatic cell score) and the 39 novel mid-infrared predicted milk traits. Results for conventional traits allowed comparison to literature showing values that were close to the expected ones. For novel traits, comparison with available literature values for Holstein breed showed generally similar estimated heritabilities. Reported average daily heritabilities estimated for the 39 novel traits tended to be higher for dpBB (0.13-0.64) than MON and NOR (0.03-0.60) breeds. Few novel traits showed large differences between breeds except between dpBB and NOR for milk composition traits. However, results for NOR breed have to be taken very carefully given the low number of animals. Even if the used methane prediction equation was not yet validated for these breeds, estimated average daily heritability was moderately high for dpBB (0.41) and MON (0.36) and moderate for NOR (0.23) indicating that this prediction might also be useful in these dual purpose breeds. [less ▲]

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See detailFirst study into the temporal relationship between metabolic disorders and lameness events over the course of a lactation
Mineur, Axelle ULiege; Egger-Danner, Christa; Sölkner, Johann et al

Conference (2018, June 25)

Lameness in dairy cows is an issue that can vary greatly in severity, and is of concern for both producers and consumers. Metabolic disorders are a major problem in themselves, and, next to this, can ... [more ▼]

Lameness in dairy cows is an issue that can vary greatly in severity, and is of concern for both producers and consumers. Metabolic disorders are a major problem in themselves, and, next to this, can cause lameness. Indeed, lameness is an often occurring consequence of various metabolic disorders, such as sub acute ruminal acidosis (SARA), ketosis or milk fever. The caused lameness event can occur weeks to months after the metabolic disorder making the detection of causality difficult. Moreover, detection of many metabolic disorders is very challenging and not straightforward. Mid-infrared (MIR) technology is already used for the prediction of major milk components, such as fat or protein, during routine milk recording and for milk payment. It was recently shown that this technology can also be used to predict novel components, linked to metabolic disorders of cows, such as ketone bodies, citrate and minerals. In the context of limiting the occurrence and severity of lameness, early prediction of lameness could help indicate the need to adapt the management and the environment of a cow at risk of lameness. Therefore, the aim of this study was to analyze the temporal link between metabolic disorders and lameness events, using locomotion scores of the cow and MIR based milk biomarkers for different metabolic disorders of her milk from previous test days. Data recorded between, July 2014 and December 2014, consisted of 9324 records, from 3895 cows and 122 farms. Correct definition of the response variable is an important aspect as extremes in lameness severity, expressed on lameness scales, were more easily predictable. First results were obtained using covariance functions on correlations computed between averaged metabolites and lameness scores, per animal, across the lactation stage classes. Correlations tended to be higher when comparing predicted metabolites with lameness in the three following months, rather than the same one, hinting at a temporal relationship. [less ▲]

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See detailInvited review: genetics and claw health: opportunities to enhance claw health by genetic selection
Heringstad, B.; Egger-Danner, C.; Charfeddine, N. et al

in Journal of Dairy Science (2018), 101(6), 4801-4821

Routine recording of claw health status at claw trimming of dairy cattle has been established in several countries, providing valuable data for genetic evaluation. In this review, we examine issues ... [more ▼]

Routine recording of claw health status at claw trimming of dairy cattle has been established in several countries, providing valuable data for genetic evaluation. In this review, we examine issues related to genetic evaluation of claw health; discuss data sources, trait definitions, and data validation procedures; and present a review of genetic parameters, possible indicator traits, and status of genetic and genomic evaluations for claw disorders. Different sources of data and traits can be used to describe claw health. Severe cases of claw disorders can be identified by veterinary diagnoses. Data from lameness and locomotion scoring, activity information from sensors, and feet and leg conformation traits are used as auxiliary traits. The most reliable and comprehensive information is data from regular hoof trimming. In genetic evaluation, claw disorders are usually defined as binary traits, based on whether or not the claw disorder was present (recorded) at least once during a defined time period. The traits can be specific disorders, composite traits, or overall claw health. Data validation and editing criteria are needed to ensure reliable data at the trimmer, herd, animal, and record levels. Different strategies have been chosen, reflecting differences in herd sizes, data structures, management practices, and recording systems among countries. Heritabilities of the most commonly analyzed claw disorders based on data from routine claw trimming were generally low, with ranges of linear model estimates from 0.01 to 0.14, and threshold model estimates from 0.06 to 0.39. Estimated genetic correlations among claw disorders varied from −0.40 to 0.98. The strongest genetic correlations were found among sole hemorrhage (SH), sole ulcer (SU), and white line disease (WL), and between digital/interdigital dermatitis (DD/ID) and heel horn erosion (HHE). Genetic correlations between DD/ID and HHE on the one hand and SH, SU, or WL on the other hand were, in most cases, low. Although some of the studies were based on relatively few records and the estimated genetic parameters had large standard errors, there was, with some exceptions, consistency among studies. Various studies evaluate the potential of various data soureces for use in breeding. The use of hoof trimming data is recommended for maximization of genetic gain, although auxiliary traits, such as locomotion score and some conformation traits, may be valuable for increasing the reliability of genetic evaluations. Routine genetic evaluation of direct claw health has been implemented in the Netherlands (2010); Denmark, Finland, and Sweden (joint Nordic evaluation; 2011); and Norway (2014), and other countries plan to implement evaluations in the near future. [less ▲]

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