Genetic improvement of laying hens viability using survival analysis

The survival of about eight generations of a large strain of laying hens was analysed separating the rearing period (RP) from the production period (PP), after hens were housed. For RP (respectively PP), 97.8% (resp., 94.1% ) of the 109 160 (resp., 100 665) female records were censored after 106 days (resp., 313 days) on the average. A Cox proportional hazards model stratified by flock (= season) and including a hatch-within-flock (HWF) fixed effect seemed to reasonably fit the RP data. For PP, this model could be further simplified to a non-stratified Weibull model. The extension of these models to sire-dam frailty (mixed) models permitted the estimation of the sire genetic variances at 0.261 ± 0.026 and 0.088 ± 0.010 for RP and PP, respectively. Heritabilities on the log scale were equal to 0.48 and 0.19. Non-additive genetic effects could not be detected. Selection was simulated by evaluating all sires and dams, after excluding all records from the last generation. Then, actual parents of this last generation were distributed into four groups according to their own pedigree index. Raw survivor curves of the progeny of extreme parental groups substantially differed (e.g., by 1.7% at 300 days for PP), suggesting that selection based on solutions from the frailty models could be efficient, despite the very large proportion of censored records

Genetic improvement of laying hens viability using survival analysis

The survival of about eight generations of a large strain of laying hens was analysed separating the rearing period (RP) from the production period (PP), after hens were housed. For RP (respectively PP), 97.8% (resp., 94.1% ) of the 109 160 (resp., 100 665) female records were censored after 106 days (resp., 313 days) on the average. A Cox proportional hazards model stratified by flock (= season) and including a hatch-within-flock (HWF) fixed effect seemed to reasonably fit the RP data. For PP, this model could be further simplified to a non-stratified Weibull model. The extension of these models to sire-dam frailty (mixed) models permitted the estimation of the sire genetic variances at 0.261 $\pm$ 0.026 and 0.088 $\pm$ 0.010 for RP and PP, respectively. Heritabilities on the log scale were equal to 0.48 and 0.19. Non-additive genetic effects could not be detected. Selection was simulated by evaluating all sires and dams, after excluding all records from the last generation. Then, actual parents of this last generation were distributed into four groups according to their own pedigree index. Raw survivor curves of the progeny of extreme parental groups substantially differed (e.g., by 1.7% at 300 days for PP), suggesting that selection based on solutions from the frailty models could be efficient, despite the very large proportion of censored records.Amélioration génétique de la viabilité des poules pondeuses à partir d'une analyse de survie. Les données de survie d'environ huit générations d'une souche de grande taille de poules pondeuses ont été analysées en séparant la période d'élevage (PE) de la période de production (PP) après la mise en cage des poules. Pour PE (respectivement PP), 97,8 % (resp., 94,1 % ) des 109 160 (resp., 100 665) performances femelles étaient censurées, après en moyenne 106 jours (resp., 313 jours). Un modèle à risques proportionnels de Cox stratifié par cheptel et incluant un effet fixé du lot de naissance intra cheptel semble décrire raisonnablement bien les données de la PE. Pour la PP, ce modèle peut être encore simplifié en un modèle de Weibull non stratifié. En étendant ces modèles à des modèles de fragilité (modèles mixtes) père-mère, les variances génétiques " pères " ont été estimées à 0,261 $\pm$ 0,026 et 0,088 $\pm$ 0,010 pour PE et PP respectivement (soit des héritabilités sur l'échelle logarithmique de 0,48 et 0,19). Il n'a pas été possible de détecter des effets génétiques non additifs. Une sélection a été simulée en évaluant tous les animaux parents, après avoir exclu les enregistrements de la dernière génération. Ensuite, les parents de cette dernière génération ont été répartis en quatre groupes suivant leur propre valeur génétique sur ascendance. Les courbes de survie brutes des descendants des groupes parentaux extrêmes diffèrent substantiellement (par exemple, de 1,7 % à 300 jours pour PP). Ceci suggère clairement qu'une sélection basée sur les solutions des modèles de fragilité pourrait être efficace, malgré la proportion très élevée de données censurées

Elaboration et évaluation d'un bulletin officinal d'information sur le médicament

LYON1-BU Santé (693882101) / SudocRENNES1-BU Santé (352382103) / SudocSudocFranceF

Etude des possibilités de réduction, par voie génétique, du risque de portage de salmonelles

National audienc

Etude des possibilités de réduction, par voie génétique, du risque de portage de salmonelles

National audienc

Smoking in French prisons: Factors associated with consumption and cessation

For the past twenty years, researchers have emphasized the importance of producing data on tobacco use among incarcerated people. With a prevalence rate that can reach 97% in some countries, smoking is much more frequent in that population compared to the general population and this constitutes one of the main causes of chronic pathologies and mortality in prisons. In France, more than 80% of inmates use tobacco while the prevalence of smoking is 31.9% in the general population in 2021. In a global context of decreasing smoking rates, tobacco use in prison contributes to the persistence of social inequalities in health. This article presents the results of a sociological study which was part of the diagnostic phase of an interventional study whose overreaching goal was to construct, implement and evaluate an intervention aiming to reduce tobacco use in prisons. The objective of this paper is to identify the factors associated with tobacco use among inmates as well as the factors that hinder or facilitate the cessation process. Qualitative interviews with 21 inmates and 30 professionals were conducted and analysed thematically, using an inductive approach and Nvivo software. In light of our findings, we discuss the importance of behavioral awareness and the community-based approach that are essential to the construction and implementation of a relevant and acceptable public health program

Detection of Listeria monocytogenes in raw and pasteurized liquid whole eggs and characterization by PFGE.

International audienceListeria monocytogenes has been recognized as a human pathogen for decades and is known to be an important foodborne pathogen. There have been no documented foodborne L. monocytogenes illnesses due to the consumption of eggs or egg products, even though the bacterium has been isolated from faeces, body fluid, and oviducts of asymptomatic laying hens. In order to describe L. monocytogenes contamination of egg products, 144 liquid whole egg samples were collected from 3 different egg-breaking plants during 3 sampling periods. L. monocytogenes detection was performed on raw samples stored at 2 degrees C for two days (D+2) and on pasteurized samples stored at 2 degrees C at D+2 and at shelf-life date (SLD). L. monocytogenes was detected in 25 of the 144 raw egg samples collected, in 4 of the 144 pasteurized egg samples at D+2 and in 2 of the 144 ones analysed at SLD. Contamination of raw egg products appeared to be season dependant and was higher during summer and winter than during autumn. One hundred and ninety-six L. monocytogenes isolates were collected and serotyped; 3 serovars were demonstrated. The dominant serovar was L. monocytogenes 1/2a which was presented by 94.4% of the isolates. Typing of 196 L. monocytogenes isolates was carried out by macrorestriction of the genomic DNA with ApaI and AscI enzymes followed by pulsed field gel electrophoresis (PFGE). A large diversity was observed with 21 genotypes of L. monocytogenes, even for a given manufacturer. Nevertheless, most of the egg product samples were contaminated by one genotype, except for five samples which were contaminated by two or three distinct genotypes. The genotypes seem to be specific to each manufacturer. No cluster of L. monocytogenes was found to recur in the different plants over successive seasons