Walloon Region Of Belgium Research Articles

A structural equation model to evaluate direct and indirect factors associated with a latent measure of mastitis in Belgian dairy herds

In dairy cattle, many farming practices have been associated with occurrence of mastitis but it is often difficult to disentangle the causal threads. Structural equation models may reduce the complexity of such situations. Here, we applied the method to examine the links between mastitis (subclinical and clinical) and risk factors such as herd demographics, housing conditions, feeding procedures, milking practices, and strategies of mastitis prevention and treatment in 345 dairy herds from the Walloon region of Belgium. During the period January 2006 to October 2007, up to 110 different herd management variables were recorded by two surveyors using a questionnaire for the farm managers and during a farm visit. Monthly somatic cell counts of all lactating cows were collected by the local dairy herd improvement association. Structural equation models were created to obtain a latent measure of mastitis and to reduce the complexity of the relationships between farming practices, between indicators of herd mastitis and between both. Robust maximum likelihood estimates were obtained for the effects of the herd management variables on the latent measure of herd mastitis. Variables associated directly (p<0.05) with the latent measure of herd mastitis were the addition of urea in the rations; the practices of machine stripping, of pre-and post-milking teat disinfection; the presence of cows with hyperkeratotic teats, of cubicles for housing and of dirty liners before milking; the treatment of subclinical cases of mastitis; and the age of the herd (latent variable for average age and parity of cows, and percentage of heifers in the herd). Treatment of subclinical mastitis was also an intermediate in the association between herd mastitis and post-milking teat disinfection. The study illustrates how structural equation model provides information regarding the linear relationships between risk factors and a latent measure of mastitis, distinguishes between direct relationships and relationships mediated through intermediate risk factors, allows the construction of latent variables and tests the directional hypotheses proposed in the model.

Estimating regional winter wheat yield with WOFOST through the assimilation of green area index retrieved from MODIS observations

Here, we describe and test a method for optimising winter wheat green area index (GAI) simulated with the WOFOST crop model using MODIS estimates of GAI in the Walloon region of Belgium. Detailed crop type maps during the period of 2000–2009 were used to derive time series of crop-specific GAI by selecting only the 250-m MODIS pixels that have at least 75% purity of the target crop. Two important model parameters were optimised by minimising the difference between the simulated and observed GAI for each individual pixel and year. The resulting year-specific joint parameter distributions were then used to run an ensemble of crop simulations in which the ensemble was initialised by sampling from the joint distribution of the corresponding year. The semi-variograms of the retrieved parameters revealed that the spatial patterns were consistent with agricultural practices and that seasonal characteristics of weather patterns in Wallonia can explain – at least partially – the temporal variability observed in the retrieved parameter distributions. Finally, the results of the average ensemble crop simulation were aggregated to the provincial and regional levels. A validation using yields reported by EUROSTAT over the period 2000–2009 revealed that assimilating MODIS with GAI provides an improved relationship between simulation results and reported yields at the regional level.

Avantages économiques du partage de l’information dans une chaîne étendue

Multimodal transport in Europe is underutilized. We propose an explanation based on the underuse by actors of the logistics industry of tools and technologies for interfacing information systems and radio frequencies in the identification of logistics flows. This adoption by the various links in the supply chain is always postponed because the economic benefits are not perceived. We propose to reassess these efficiency benefits using other criteria. Shippers, their customers and carriers are penalized by malfunctions, delays and other deviations from normal flow. This approach is based on the analysis carried out within the framework of the TransLogisTlC project financed by the Walloon Region in Belgium. Thanks to the new services offered in the form of shared access software, the means and results presented apply in particular to SMEs in transport and logistics services, which make up the main sector in Europe.

Using test station and on-farm data for the genetic evaluation of Piétrain boars used on Landrace sows for growth performance1

The aim of this study was to develop a new genetic evaluation model to estimate the genetic merit of boars for growth based on 1) performance of their crossbred progeny fattened in the test station and 2) their own performance or those of relatives from the on-farm testing system. The model was a bivariate random regression animal model with linear splines and was applied to Piétrain boars from the Walloon Region of Belgium mated with Landrace sows. Data contained 1) 12,610 BW records from the test station collected on 1,435 crossbred pigs from Piétrain boars and Landrace sows, and 2) 52,993 BW records from the on-farm testing system collected on 50,670 pigs with a breed composition of at least 40% Piétrain or Landrace. Since 2007, 56 Piétrain boars have been tested in the station. Data used to estimate variance components and breeding values were standardized for the age to take into account heterogeneity of variances and then pre-adjusted at 210 d of age to put all records on the same scale. Body weight records from the test station and from the on-farm testing system were considered as 2 different traits. The heterosis effect was modeled as fixed regression on the heterozygosity coefficient. As all test station animals were similarly crossbred, smaller variation in heterozygosity caused the sampling error of the regression estimate at 210 d to be larger in the test station than in on-farm data with estimates of 28.35 ± 14.55 kg and 9.02 ± 0.67 kg, respectively. Therefore, the most likely reason for the large differences in estimates was sampling. Heritability estimates ranged from 0.37 to 0.60 at 210 and 75 d, respectively, for test station BW and from 0.42 to 0.60 at 210 d and 175 d, respectively, for on-farm BW. Genetic correlation decreased when the age interval between records increased, and were greater between ages for test station than for on-farm data. Genetic correlations between test station and on-farm BW at the same age were high: 0.90 at 175 d and 0.85 at 210 d. For the 56 boars tested in the station, the average reliability of their EBV for ADG between 100 and 210 d was improved from 0.60 using only test station data to 0.69 using jointly test station and on-farm data. Based on these results, the new model developed was considered as a good method of detection of differences in growth potential of Piétrain boars based on test station and on-farm data.

A regional flux-based risk assessment approach for multiple contaminated sites on groundwater bodies

In the context of the Water Framework Directive (EP and CEU, 2000), management plans have to be set up to monitor and to maintain water quality in groundwater bodies in the EU. In heavily industrialized and urbanized areas, the cumulative effect of multiple contaminant sources is likely and has to be evaluated. In order to propose adequate measures, the calculated risk should be based on criteria reflecting the risk of groundwater quality deterioration, in a cumulative manner and at the scale of the entire groundwater body. An integrated GIS- and flux-based risk assessment approach for groundwater bodies is described, with a regional scale indicator for evaluating the quality status of the groundwater body. It is based on the SEQ-ESO currently used in the Walloon Region of Belgium which defines, for different water uses and for a detailed list of groundwater contaminants, a set of threshold values reflecting the levels of water quality and degradation with respect to each contaminant. The methodology is illustrated with first results at a regional scale on a groundwater body-scale application to a contaminated alluvial aquifer which has been classified to be at risk of not reaching a good quality status by 2015. These first results show that contaminants resulting from old industrial activities in that area are likely to contribute significantly to the degradation of groundwater quality. However, further investigations are required on the evaluation of the actual polluting pressures before any definitive conclusion be established.

Phenotypic and genetic variability of production traits and milk fatty acid contents across days in milk for Walloon Holstein first-parity cows

The objective of this study was to assess the phenotypic and genetic variability of production traits and milk fatty acid (FA) contents throughout lactation. Genetic parameters for milk, fat, and protein yields, fat and protein contents, and 19 groups and individual FA contents in milk were estimated for first-parity Holstein cows in the Walloon Region of Belgium using single-trait, test-day animal models and random regressions. Data included 130,285 records from 26,166 cows in 531 herds. Heritabilities indicated that de novo synthesized FA were under stronger genetic control than FA originating from the diet and from body fat mobilization. Estimates for saturated short- and medium-chain individual FA ranged from 0.35 for C4:0 to 0.44 for C8:0, whereas those for monounsaturated long-chain individual FA were lower (around 0.18). Moreover, de novo synthesized FA were more heritable in mid to late lactation. Approximate daily genetic correlations among traits were calculated as correlations between daily breeding values for days in milk between 5 and 305. Averaged daily genetic correlations between milk yield and FA contents did not vary strongly among FA (around −0.35) but they varied strongly across days in milk, especially in early lactation. Results indicate that cows selected for high milk yield in early lactation would have lower de novo synthesized FA contents in milk but a slightly higher content of C18:1 cis-9, indicating that such cows might mobilize body fat reserves. Genetic correlations among FA emphasized the combination of FA according to their origin: contents in milk of de novo FA were highly correlated with each other (from 0.64 to 0.99). Results also showed that genetic correlations between C18:1 cis-9 and other FA varied strongly during the first 100 d in milk and reinforced the statement that the release of long-chain FA inhibits FA synthesis in the mammary gland while the cow is in negative energy balance. Finally, results showed that the FA profile in milk changed during the lactation phenotypically and genetically, emphasizing the relationship between the physiological status of cow and milk composition.

Assessing the contribution of electrical resistivity tomography (ERT) and self-potential (SP) methods for a water well drilling program in fractured/karstified limestones

ERT and SP investigations were conducted in carbonate rocks of the Dinant Synclinorium (Walloon Region of Belgium) to find suitable locations for new water wells in zones with little hydrogeological data. Since boreholes information needed to be representative of the area, large fractured zones were searched for the drillings. Large ERT profiles (320 to 640 m) allowed us to image the resistivity distribution of the first 60 m of the subsurface and to detect and characterize (in terms of direction, width and depth) fractured zones expected to be less resistive. Data errors, depth of investigation (DOI) indexes and sensitivity models were analyzed in order to avoid a misinterpretation of the resulting images. Self-potential measurements were performed along electrical profiles to complement our electrical results. Some negative anomalies possibly related to preferential flow pathways were detected. A drilling campaign was conducted according to geophysical results. ‘Ground truth’ geological data as well as pumping tests information gave us a way to assess the contribution of geophysics to a drilling program. We noticed that all the wells placed in low resistivity zones associated with SP anomalies provide very high yields and inversely, wells drilled in resistive zones or outside SP anomalies are limited in terms of capacity. An apparent coupling coefficient between SP signals and differences in hydraulic heads was also estimated in order to image the water table.

An international comparison of four quantitative risk assessment approaches—A benchmark study based on a fictitious LPG plant

In order to compare the quantitative risk assessment (QRA) methods for land use planning and licensing used in France, the United Kingdom, The Netherlands and the Walloon Region of Belgium, a benchmark exercise was performed. Based on a description of a fictitious LPG storage plant, INERIS from France, HSE from the United Kingdom, the Faculté Polytechnique de Mons from the Walloon Region of Belgium and the RIVM from The Netherlands used their own quantitative risk assessment approach to perform the exercise.The risk assessment approaches to determine third party risks of a LPG plant used by the four partners are very different. In France the assessment is based on a specific on-site analysis performed by experts. HSE uses a simple consequence based approach to determine safety distances. In The Netherlands and the Walloon Region a generic and standardized method for determining the risk contours is used.The differences relate to the calculation methodologies and the types of consequences that are calculated (such as lethal effects or irreversible effects). Despite the differences, the methods yield to similar safety distances between houses and companies: distances between 200 and 280m. However, similar safety distances can still have different policy implications. For instance, the safety distances in The Netherlands and France are used as limit values, whereas in Belgium and the United Kingdom they are used to give an advice.

HydroCube: un modelo de datos hidrogeológicos basado en la relación de entidades

Managing, handling and accessing hydrogeological information depends heavily on the applied hydrogeological data models, which differ between institutions and countries. The effective dissemination of hydrogeological information requires the convergence of such models to make hydrogeological information accessible to multiple users such as universities, water suppliers, and administration and research organisations. Furthermore, because hydrogeological studies are complex, they require a wide variety of high-quality hydrogeological data with appropriate metadata in clearly designed and coherent structures. A need exists, therefore, to develop and implement hydrogeological data models that cover, as much as possible, the full hydrogeological domain. A new data model, called HydroCube, was developed for the Walloon Region in Belgium in 2005. The HydroCube model presents an innovative holistic project-based approach which covers a full set of hydrogeological concepts and features, allowing for effective hydrogeological project management. The model stores data relating to the project locality, hydrogeological equipment, and related observations and measurements. In particular, it focuses on specialized hydrogeological field experiments such as pumping and tracer tests. This logical data model uses entity-relationship diagrams and it has been implemented in the Microsoft Access environment. It has been enriched with a fully functional user interface.

Different estimations of heritabilities in dependence of major gene effects (Brief Report)

Abstract. Knowledge of major gene effects for quantitative traits (e.g. milk performance traits) and the consequent selection of animals with desirable genotypes can accelerate breeding progress and can therefore equal large gain in profits. It is generally accepted that in most cases, the total breeding value for quantitative traits of any animal can be divided in one or some major gene effects and a pure random polygenic component, in which the latter results from a finite number of remaining loci (FERNANDO et al. 1994). Thus, the aim of this study was to investigate, how the estimation of heritability is influenced by the application of two different models, one of them containing a major single gene effect. The myostatin gene (MSTN) was chosen because the knowledge of this gene effect is used for selection decisions in the Dual Purpose Belgian Blue Breed (DP-BBB) in the Walloon Region of Belgium.

Modelling the effects of the current policy measures in agriculture: An unique model from field to regional scale in Walloon region of Belgium

▶ Modelling diffuse nutrient losses from agriculture implies physically based hydrological model. ▶ The model must be consistent whatever the reporting unit is. ▶ In Wallonia, 8% of the groundwater bodies need over 15 years to be impacted by mitigation measures. ▶ Currently, catch crops and the weather mostly impacts nutrient mitigation. ▶ A sensitivity analysis of the future weather's effect is necessary. Diffuse nutrient loss from agriculture into the soil, groundwater and surface water affects their quality. Different policies are in force throughout the European Union aiming for their limitation. They were implemented through action plans on a regional scale. Hydrological modelling can be a powerful method for efficiently evaluating their effectiveness. In order to be useful whatever the action and for every reporting unit (whole Region, water bodies, nitrate vulnerable zones, fields...) the model must be physically based, it must simulate water and nutrient fluxes in the root zone and the vadose zone as well as being geographically flexible. This paper presents such a model and its application in the context of Wallonia (Southern part of Belgium). It also presents a calculation of what water and nutrient flows could be under a given climatic scenario until 2015. In Belgium, water quality depends upon Regions. Wallonia implemented the European Nitrate Directive through two action plans the first in 2002 and the second in 2007. These actions plans were modelled and compared to a scenario without any modification in the farmers’ practices. The modelling showed the need for two indicators: nitrate concentration under the root zone as fast indicator of the actions’ efficiency and transfer time from surface to groundwater table. The first action plan hardly modified farmers’ field practices and consequently it did not impact water quality. The second action plan had more impact (reduction up to 10 mg/l NO 3 under the root zone). It was mainly due to catch crop introduction in the nitrate vulnerable zone, if they are followed by a reduction of the mineral fertilisation (not mandatory). Our results show that new actions are necessary. We show where and to what extent they have to be implemented. Nevertheless, the greatest variation in nitrate leaching from the root zone seems to be dependent on the weather, more than the action plans. Particularly the rainy period between 1998 and 2002 had a huge impact on nitrogen flows. Our hydrological modelling is showed to be a powerful tool of nitrogen management in a still uncertain climatic evolution context. Finally, we showed that patience and perseverance will be necessary to reach the targets of the WFD in the Walloon context. The map of transfer time shows that 8% of the groundwater bodies need over 15 years to be impacted by mitigation measures.

Short communication: Genetic variation of saturated fatty acids in Holsteins in the Walloon region of Belgium

Random regression test-day models using Legendre polynomials are commonly used for the estimation of genetic parameters and genetic evaluation for test-day milk production traits. However, some researchers have reported that these models present some undesirable properties such as the overestimation of variances at the edges of lactation. Describing genetic variation of saturated fatty acids expressed in milk fat might require the testing of different models. Therefore, 3 different functions were used and compared to take into account the lactation curve: (1) Legendre polynomials with the same order as currently applied for genetic model for production traits; 2) linear splines with 10 knots; and 3) linear splines with the same 10 knots reduced to 3 parameters. The criteria used were Akaike's information and Bayesian information criteria, percentage square biases, and log-likelihood function. These criteria indentified Legendre polynomials and linear splines with 10 knots reduced to 3 parameters models as the most useful. Reducing more complex models using eigenvalues seemed appealing because the resulting models are less time demanding and can reduce convergence difficulties, because convergence properties also seemed to be improved. Finally, the results showed that the reduced spline model was very similar to the Legendre polynomials model.

Abstract 4917: A four-gene methylation marker panel as triage test in hr-HPV positive patients

Abstract Objective: Currently no cervical neoplasia specific methylation markers with high sensitivity and specificity are available for use in population-based screening on (pre)malignant cervical neoplasia. Aim of the study was to identify new methylation markers and to design and validate a methylation marker panel for triage of hr-HPV positive patients. Methods: Quantitative methylation specific PCRs (MSP) on OpenArray™ platform, representing 424 primers of 213 cancer specific methylated genes, were performed on frozen tissue samples from 84 cervical cancer patients and 106 normal cervices. The top 20 of ranked methylation markers were validated by LightCycler® MSP experiments. Then the top 3 methylation markers based on ROC analysis were selected for further clinical validation in combination with C13ORF18 (previously identified by our group), on cervical scrapings from 74 cervical cancer patients, 69 normal cervices and 148 patients referred with an abnormal Pap smear. Finally, a scenario analysis for population based screening program was performed to compare the diagnostic performance of our methylation panel to conventional liquid based cytology after primary hr-HPV testing. Results: Three cervical neoplasia specific methylation markers (JAM3, EPB41L3 and TERT) discriminated strongly between cervical scrapings from cervical cancer patients and healthy controls (p&amp;lt;0.0001). Our methylation panel (JAM3, EPB4lL3, TERT and C13ORF18) detected 94% of cervical cancers, 82% CIN3+ and 65% CIN2+, while specificity was 79% for CIN0/1 lesions. Scenario analysis showed that primary hr-HPV testing combined with our methylation marker panel as a triage test resulted in a higher identification of CIN3 and cervical cancers, a higher percentage of correct referrals and less patient-doctor contacts compared to hr-HPV testing in combination with liquid based cytology. Conclusion: Our study resulted in the discovery of three new cervical neoplasia specific methylation markers. Our methylation panel comprising 4 genes might be an alternative triage test after primary hr-HPV testing and its possible application deserves to be further explored in large population-based screening programs for cervical neoplasia. This study was supported by OncoMethylome Sciences S.A., Liège, Belgium, by the Dutch Cancer Society (NKB) (project-number RUG 2004-3161) and by the “Direction générale des Technologies, de la Recherche et de l'Énergie” of the Walloon Region of Belgium. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4917.

Development of a new crossbreed based evaluation for carcass quality of Piétrain boars in the Walloon Region of Belgium

Development of a new crossbreed based evaluation for carcass quality of Pietrain boars in the Walloon Region of Belgium M Dufrasne, H Hammami, V Jaspart, J Wavreille, N Gengler University of Liege Gembloux Agro-Bio Tech, Gembloux, Belgium, Walloon Pig Breeders Association, Ciney, Belgium, Walloon Agricultural Research Centre, Gembloux, Belgium, National Fund for Scientific Research, Brussels, Belgium Email: Marie.Dufrasne@ulg.ac.be

Detailed Inundation Modelling Using High Resolution DEMs

With the availability of high resolution DEMs, relevant and detailed inundation maps may now be routinely computed provided that suitable flow models are available. The full 2D flow model presented in this paper has been used to compute such maps on 800 km of the main rivers of the Walloon Region in Belgium. The use of grid spacing of 1 m, similar to the DEM resolution, enables the accurate prediction of the pattern of flood depth. This is confirmed by several application examples, which also demonstrate the ability of the model to reproduce depth measurements for a wide range of flood discharges without the need for recalibration of the roughness coefficient. The numerical model has been systematically validated by comparison with observations during recent real flood events. It shows a very good agreement with field data, in particular the free surface elevations and inundation extension.

Modeling milk urea of Walloon dairy cows in management perspectives

The aim of this study was to develop an adapted random regression test-day model for milk urea (MU) and to study the possibility of using predictions and solutions given by the model for management purposes. Data included 607,416 MU test-day records of first-lactation cows from 632 dairy herds in the Walloon Region of Belgium. Several advanced features were used. First, to detect the herd influence, the classical herd × test-day effect was split into 3 new effects: a fixed herd × year effect, a fixed herd × month-period effect, and a random herd test-day effect. A fixed time period regression was added in the model to take into account the yearly oscillations of MU on a population scale. Moreover, first autoregressive processes were introduced and allowed us to consider the link between successive test-day records. The variance component estimation indicated that large variance was associated with the random herd × test-day effect (48% of the total variance), suggesting the strong influence of herd management on the MU level. The heritability estimate was 0.13. By comparing observed and predicted MU levels at both the individual and herd levels, target ranges for MU concentrations were defined to take into account features of each cow and each herd. At the cow level, an MU record was considered as deviant if it was <200 or >400mg/L (target range used in the field) and if the prediction error was >50mg/L (indicating a significant deviation from the expected level). Approximately 7.5% of the MU records collected between June 2007 and May 2008 were beyond these thresholds. This combination allowed for the detection of potentially suspicious cows. At the herd level, the expected MU level was considered as the sum of the solutions for specific herd effects. A herd was considered as deviant from its target range when the prediction error was greater than the standard deviation of MU averaged by herd test day. Results showed that 6.7% of the herd test-day MU levels between June 2007 and May 2008 were considered deviant. These deviations seemed to occur more often during the grazing period. Although theoretical considerations developed in this study should be validated in the field, this research showed the potential use of a test-day model for analyzing functional traits to advise dairy farmers.

Statistical analysis of indoor radon data for the Walloon region (Belgium)

Two databases of indoor radon measurements in the Walloon region in Belgium can be used to establish a radon risk map of this region, taking into account the geological information. The data were collected, respectively, by long-term track-etch measurements and by short-term charcoal measurements. Here we present a preliminary study showing that the two databases can be merged. We begin our study by testing two types of distributions: the log-normal distribution and the log-Gumbel distribution, with the purpose of selecting the best to fit our databases. The paper then describes a methodology that allows us to combine them. The composite database will be used to establish a radon risk map for the Walloon region based on geology.

Assessing and conserving groundwater biodiversity: an introduction

Summary1. This paper is an introduction to and overview of a special issue on groundwater ecology with a focus on biodiversity assessment and conservation. The subterranean environment harbours unique biological communities of remarkable diversity, comprising both microorganisms and micro‐, meio‐ and macrofauna. This biodiversity of ground waters remains poorly known compared to that of freshwater surface habitats.2. The papers in this special issue summarise the outcome of a large‐scale European survey, the PASCALIS project (Protocol for theASsessment andConservation ofAquaticLifeIn theSubsurface), complemented by results from a few other comprehensive studies on groundwater diversity. The papers fall into five broad groups. The first group reviews the biology and ecology of poorly investigated but important subterranean taxa such as Bacteria and Archaea, Oligochaeta and Copepoda. Five papers deal with groundwater biodiversity patterns in the six selected PASCALIS regions. Issues addressed range from broad‐scale diversity patterns to partitioning of species richness, cryptic diversity, sampling methodology, and the use of surrogate taxonomic groups for assessing overall diversity. Four papers analyse biodiversity patterns in single European regions, the French Jura, the Walloon region of Belgium, the Lessinian Mountains of Italy and south‐western Germany. Two additional papers address the issue of site selection for the conservation and protection of groundwater species, and the fifth group of three papers expands two central PASCALIS themes – sampling adequacy and the role of dispersal. Finally, a concluding synthesis paper summarises advances in understanding groundwater biodiversity patters and conservation and points out important challenges for future research.3. Collectively, the information presented in this special issue represents the first broad‐scale examination of aquatic subterranean diversity based on a rigorously standardised sampling protocol, the first examination of stygofauna patterns in both karstic and non‐karstic aquifers, a first step toward integrating traditional and molecular taxonomic studies of groundwater biodiversity, and a start toward elaborating strategies for groundwater reserve selection.

Evaluation of radar-gauge merging methods for quantitative precipitation estimates

Abstract. Accurate quantitative precipitation estimates are of crucial importance for hydrological studies and applications. When spatial precipitation fields are required, rain gauge measurements are often combined with weather radar observations. In this paper, we evaluate several radar-gauge merging methods with various degrees of complexity: from mean field bias correction to geostatistical merging techniques. The study area is the Walloon region of Belgium, which is mostly located in the Meuse catchment. Observations from a C-band Doppler radar and a dense rain gauge network are used to estimate daily rainfall accumulations over this area. The relative performance of the different merging methods are assessed through a comparison against daily measurements from an independent gauge network. A 4-year verification is performed using several statistical quality parameters. It appears that the geostatistical merging methods perform best with the mean absolute error decreasing by 40% with respect to the original data. A mean field bias correction still achieves a reduction of 25%. A seasonal analysis shows that the benefit of using radar observations is particularly significant during summer. The effect of the network density on the performance of the methods is also investigated. For this purpose, a simple approach to remove gauges from a network is proposed. The analysis reveals that the sensitivity is relatively high for the geostatistical methods but rather small for the simple methods. The geostatistical merging methods give the best results for all tested network densities and their relative benefit increases with the network density.

Estimation of Heritability and Genetic Correlations for the Major Fatty Acids in Bovine Milk

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.