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See detailEstimation of fatty acid profile in cow milk by mid-infrared spectrometry
Soyeurt, Hélène ULg; Dardenne, Pierre; Lognay, Georges ULg et al

Poster (2006, April 03)

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See detailEstimation of fatty acid profile in cow milk by mid-infrared spectrometry
Soyeurt, Hélène ULg; Dardenne, Pierre; Lognay, Georges ULg et al

in European seminar on infrared spectroscopy (2006)

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See detailEstimation of fructose, glucose and sucrose released by inulin hydrolysis during food processing.
Chevalier, Jean-Paul; Paquot, Michel; Fougnies, C. et al

Poster (2003, May)

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See detailEstimation of furan contamination across the Belgian food chain.
Scholl, Georges ULg; Scippo, Marie-Louise ULg; De Pauw, Edwin ULg et al

in Food Additives & Contaminants. Part A. Chemistry, Analysis, Control, Exposure & Risk Assessment (2012), 29(2), 172-9

This paper provides an estimate of the furan content of Belgian foods. The objective of the study was to achieve the best food chain coverage with a restricted number of samples (n = 496). The geographic ... [more ▼]

This paper provides an estimate of the furan content of Belgian foods. The objective of the study was to achieve the best food chain coverage with a restricted number of samples (n = 496). The geographic distribution, different market chains and labels, and consumption frequencies were taken into account in the construction of the sampling plan. Weighting factors such as contamination levels, consumption frequency and the diversity of food items were applied to set up the model. The very low detection capabilities (CC(beta)) of the analytical methods used (sub-ppb) allowed reporting of 78.2% of the overall dataset above CC(beta) and, in particular, 96.7% for the baby food category. The highest furan levels were found in powdered roasted bean coffee (1912 microg kg(-1)) with a mean of 756 microg kg(-1) for this category. Prepared meat, pasta and rice, breakfast cereals, soups, and baby food also showed high mean furan contents ranging from 16 to 43 microg kg(-1). Comparisons with contamination surveys carried out in other countries pointed out differences for the same food group and therefore contamination levels are related to the geographical origin of food items. [less ▲]

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See detailEstimation of genetic and crossbreeding parameters for daily milk yield of Ayrshire × Sahiwal × Ankole crossbred cows in Burundi
Hatungumukama, G.; Detilleux, Johann ULg

in Livestock Science (2008)

The pedigree of 317 cows of which 184 were controlled for milk production has been used to estimate crossbreeding parameters for daily milk yield of Ayrshire, Sahiwal and Ankole crosses in the Mahwa ... [more ▼]

The pedigree of 317 cows of which 184 were controlled for milk production has been used to estimate crossbreeding parameters for daily milk yield of Ayrshire, Sahiwal and Ankole crosses in the Mahwa station. Lactating cows belonged to one of 6 different genetic groups defined on the basis of the mating system used to produce them. REML estimates of the genetic parameters were obtained with a repeated animal model using daily milk records. Estimated heritability (h2) and repeatability (r2) were 0.27 and 0.36, respectively. The genetic group effects were used to estimate crossbreeding parameters following Dickerson's genetic model. Estimates for the additive effects for daily milk yield of Ankole, Sahiwal and Ayrshire breeds were − 1.66l, − 0.48l and 5.22l, respectively. Estimates of direct heterosis for daily milk yield for Sahiwal × Ankole, Ayrshire × Ankole, and Ayrshire × Sahiwal crosses were 1.97l, 2.30l and − 2.33l, respectively. [less ▲]

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See detailEstimation of genetic correlations among countries in international dairy sire evaluations with structural models.
Leclerc, H.; Minery, S.; Delaunay, I. et al

in Journal of Dairy Science (2006), 89(5), 1792-803

The increase in the number of participating countries and the lack of genetic ties between some countries has lead to statistical and computational difficulties in estimating the genetic (co)variance ... [more ▼]

The increase in the number of participating countries and the lack of genetic ties between some countries has lead to statistical and computational difficulties in estimating the genetic (co)variance matrix needed for international sire evaluation of milk yield and other traits. Structural models have been proposed to reduce the number of parameters to estimate by exploiting patterns in the genetic correlation matrix. Genetic correlations between countries are described as a simple function of unspecified country characteristics that can be mapped in a space of limited dimensions. Two link functions equal to the exponential of minus the Euclidian distance between the coordinates of two countries and the exponential of minus the square of this Euclidian distance were used for the study on international simulated and field data. On simulated data, it was shown that structural models might allow an easier estimation of genetic correlations close to the border of the parameter space. This is not always possible with an unstructured model. On milk yield data, genetic correlations obtained from 22 countries for structural models based on 2 and 7 dimensions, respectively, were analyzed. Only a structural model with a large number of axes gave reasonable estimates of genetic correlations compared with correlations obtained for an unstructured model: 76.7% of correlations deviated by less than 0.030. Such a model reduces the number of parameters from 231 genetic correlations to 126 coordinates. On foot angle data, large deviations were observed between genetic correlations estimated with an unstructured model and correlations estimated with a structural model, regardless of the number of axes taken into account. [less ▲]

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See detailEstimation of genetic covariances with Method R
Druet, Tom ULg; Misztal, I.; Duangjinda, M. et al

in Journal of Animal Science (2001), 79(3), 605-615

Method R is a simple and computationally inexpensive method for estimating (co)variances. The objective of the study was to investigate properties of Method R for estimation of (co)variance components ... [more ▼]

Method R is a simple and computationally inexpensive method for estimating (co)variances. The objective of the study was to investigate properties of Method R for estimation of (co)variance components with emphasis on covariance estimation. Theoretical Method R formulas were developed for simplified single-variate and bivariate models. In single-trait models, the curve of the regression of Method R was continuous and monotonic and its slope depended on the amount of information on each animal and on the variance ratio. The curve became steeper as the number of records per animal decreased. For covariance, the curve of the regression was monotonic but not continuous. However, a regression coefficient of 1 still corresponded to the correct covariance. Similar curves were observed in analyses of simulated data sets. Because of the observed discontinuity, algorithms implementing Method R that require a continuous regression curve would not work in models with: covariances. An alternative algorithm was based on a transformation matrix obtained by multiplying a matrix of numerators with the inverse of a matrix of denominators of the regression factors. Such an algorithm converged reliably for all models tested. Method R can be modified to estimate covariances in models too large for other methods. [less ▲]

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See detailEstimation of genetic parameters and genome scan for 15 semen characteristics traits of Holstein bulls.
Druet, Tom ULg; Fritz, S.; Sellem, E. et al

in Journal of Animal Breeding & Genetics (2009), 126(4), 269-77

A QTL detection experiment was performed in French dairy cattle to search for QTL related to male fertility. Ten families, involving a total of 515 bulls, were phenotyped for ejaculated volume and sperm ... [more ▼]

A QTL detection experiment was performed in French dairy cattle to search for QTL related to male fertility. Ten families, involving a total of 515 bulls, were phenotyped for ejaculated volume and sperm concentration, number of spermatozoa, motility, velocity, percentage of motile spermatozoa after thawing and abnormal spermatozoa. A set of 148 microsatellite markers were used to realize a genome scan. First, genetic parameters were estimated for all traits. Semen production traits were found to have moderate heritabilities (from 0.15 to 0.30) while some of the semen quality traits such as motility had high heritabilities (close to 0.60). Genetic correlations among traits showed negative relationships between volume and concentration and between volume and most quality traits such as motility or abnormal sperm while correlations between concentration and these traits were rather favourable. Percentages of abnormal sperm were negatively related to quality traits, especially with motility and velocity of spermatozoa. Three QTL related to abnormal sperm frequencies were significant at p < 0.01. In total, 11 QTL (p < 0.05) were detected. However, the number of QTL detected was within the range of expected false positives. Because of the lack of power to find QTL in this design further analyses are required to confirm these QTL. [less ▲]

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See detailEstimation of genetic parameters for birth weight, pre-weaning mortality and hot carcass weight in a crossbred population of pigs
Dufrasne, Marie ULg; Misztal, Ignacy; Tsuruta, Shogo et al

in Journal of Animal Science (2012), 90(E-Suppl.3), 721

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See detailEstimation of genetic parameters for birth weight, pre-weaning mortality and hot carcass weight in a crossbred population of pigs
Dufrasne, Marie ULg; Misztal, Ignacy; Tsuruta, Shogo et al

Conference (2012, July 18)

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See detailEstimation of genetic parameters for birth weight, preweaning mortality, and hot carcass weight of crossbred pigs
Dufrasne, Marie ULg; Misztal, Ignacy; Tsuruta, Shogo et al

in Journal of Animal Science (2013), 91

Genetic parameters for birth weight (BWT), preweaning mortality (PWM), and hot carcass weight (HCW) were estimated for a crossbred pig population to determine if BWT could be used as an early predictor ... [more ▼]

Genetic parameters for birth weight (BWT), preweaning mortality (PWM), and hot carcass weight (HCW) were estimated for a crossbred pig population to determine if BWT could be used as an early predictor for later performances. Sire genetic effects for those traits were estimated to determine if early selection of purebred sires used in crossbreeding could be improved. Data were recorded from one commercial farm between 2008 and 2010. Data were from 24,376 crossbred pigs from Duroc sires and crossbred Large White × Landrace dams and included 24,376 BWT and PWM records, and 13,029 HCW records. For the analysis, PWM was considered as a binary trait (0 for live or 1 for dead piglet at weaning). A multi-trait threshold-linear animal model was used, with animal effect divided into sire genetic and dam effects; the dam effects included both genetic and environmental variation due to the absence of pedigree information for crossbred dams. Fixed effects were sex and parity for all traits, contemporary groups for BWT and HCW, and age at slaughter as a linear covariable for HCW. Random effects were sire additive genetic, dam, litter, and residual effects for all traits, and contemporary group for PWM. Heritability estimates were 0.04 for BWT, 0.02 for PWM, and 0.12 for HCW. Ratio between sire genetic and total estimated variances was 0.01 for BWT and PWM, and 0.03 for HCW. Dam and litter variances explained respectively 14% and 15% of total variance for BWT, 2% and 10% for PWM, and 3% and 8% for HCW. Genetic correlations were −0.52 between BWT and PWM, 0.55 between BWT and HCW, and -0.13 between PWM and HCW. Selection of purebred sires for higher BWT of crossbreds may slightly improve survival until weaning and final market weight at the commercial level. [less ▲]

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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

Conference (2012, August 30)

The aim of this study was to estimate the genetic parameters for longitudinal measurements of feed intake (FI) in a crossbred population of pigs to develop a genetic evaluation model for the estimation of ... [more ▼]

The aim of this study was to estimate the genetic parameters for longitudinal measurements of feed intake (FI) in a crossbred population of pigs to develop a genetic evaluation model for the estimation of breeding values for FI of Piétrain boars. Data were collected on crossbred pigs in test station in the context of the genetic evaluation system of Piétrain boars in the Walloon Region of Belgium. Trait analyzed was daily FI (DFI). Because there were no facilities to record individual DFI in the Walloon test station, individual DFI were assumed to be the total pen FI divided by the number of pigs per pen. The edited dataset consisted of 3,902 measurements of DFI recorded on 1,975 crossbred pigs from 75 purebred Piétrain sires and 150 Landrace dams from the hyperprolific Landrace K+ line. A random regression animal model with fixed effects of sex and pen, and random effects of additive genetic, permanent environment and residual was developed in this study. Random additive genetic and permanent environment effects were modeled with linear splines with knots located at 75, 100, 175 and 210 d. The mean DFI was 1.979 kg/d with a SD of 0.479 kg/d. Estimated heritability for DFI increased with age from 0.02 at 75 d to 0.30 at 210 d. Estimated genetic correlation between age decreased when age interval increased. These preliminary results are consistent with literature. However, additional research are ongoing to test alternative random regression models that should be better than using splines for longitudinal performance of DFI. Furthermore, genetic relationship between DFI and other production traits, like growth and carcass traits, must be analyzed. [less ▲]

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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)

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

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

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

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

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See detailEstimation of genetic parameters for quantitative trait loci for dairy traits in the French Holstein population.
Druet, Tom ULg; Fritz, S.; Boichard, D. et al

in Journal of Dairy Science (2006), 89(10), 4070-6

A marker-assisted selection program (MAS) has been implemented in dairy cattle in France. The efficiency of such a selection program depends on the use of correct genetic parameters for the marked ... [more ▼]

A marker-assisted selection program (MAS) has been implemented in dairy cattle in France. The efficiency of such a selection program depends on the use of correct genetic parameters for the marked quantitative trait loci (QTL). Therefore, the objective of this study was to estimate the proportion of genetic variance explained by 4 QTL described in previous studies (these QTL are segregating on chromosomes 6, 14, 20, and 26). Genotypes for 11 markers were available for 3,974 bulls grouped within 54 sire families of the French Holstein population undergoing MAS. The parameters were estimated for 4 QTL and 5 dairy traits: milk, fat and protein yields, and fat and protein percentages. The proportion of genetic variance explained by the QTL ranged from as low as 0.03 to 0.36%. Both lack of marker informativity and poor monitoring of QTL transmission might limit the accuracy of estimation. The QTL explained a larger proportion of genetic variance for milk composition traits. The QTL on chromosome 14 and chromosomes 6 and 20 have their largest influence on fat and protein percentages, respectively. The overall proportions of genetic variance explained by the QTL were 27.0, 30.7, 24.1, 48.2, and 33.6% for milk, fat and protein yields, and fat and protein percentages, respectively. These results clearly indicated that a large part of the genetic variance is explained by a small number of QTL and that their use in MAS might be beneficial for dairy cattle breeding programs. [less ▲]

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See detailEstimation of Genetic Parameters for Test Day Milk Yields of Moroccan Holstein Cows Using Random Regression Test Day Model
Tijani, Aziz; Rgayai, Brahim; Hammami, Hedi ULg et al

Poster (2010, August 02)

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See detailEstimation of Genetic Parameters for Test Day Milk Yields of Moroccan Holstein Cows Using Random Regression Test Day Model
Tijani, Aziz; Rgayai, Brahim; Hammami, Hedi ULg et al

in Proceedings of the 9th World Congress on Genetics Applied to Livestock Production (2010, August)

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See detailEstimation of genetic parameters for test day records of dairy traits in the first three lactations.
Druet, Tom ULg; Jaffrezic, Florence; Ducrocq, Vincent

in Genetics, Selection, Evolution (2005), 37(3), 257-71

Application of test-day models for the genetic evaluation of dairy populations requires the solution of large mixed model equations. The size of the (co)variance matrices required with such models can be ... [more ▼]

Application of test-day models for the genetic evaluation of dairy populations requires the solution of large mixed model equations. The size of the (co)variance matrices required with such models can be reduced through the use of its first eigenvectors. Here, the first two eigenvectors of (co)variance matrices estimated for dairy traits in first lactation were used as covariables to jointly estimate genetic parameters of the first three lactations. These eigenvectors appear to be similar across traits and have a biological interpretation, one being related to the level of production and the other to persistency. Furthermore, they explain more than 95% of the total genetic variation. Variances and heritabilities obtained with this model were consistent with previous studies. High correlations were found among production levels in different lactations. Persistency measures were less correlated. Genetic correlations between second and third lactations were close to one, indicating that these can be considered as the same trait. Genetic correlations within lactation were high except between extreme parts of the lactation. This study shows that the use of eigenvectors can reduce the rank of (co)variance matrices for the test-day model and can provide consistent genetic parameters. [less ▲]

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See detailEstimation of genetic parameters for test-day records of French Holstein cows with an AI-REML algorithm
Druet, Tom ULg; Jaffrézic, F.; Ducrocq, V.

in Abstracts from the 2003 ADSA/ASAS joint annual meeting (2003)

Detailed reference viewed: 3 (0 ULg)