Modelling the kinetics of milk emission during machine milking in dairy ewes

The individual milking time is one of the aspects which affect the routine of milking in dairy ewes and the time to devote to this laborious task. The positive effect of an appropriate udder conformation in the reduction of manual interventions (stripping) during milking, have been clarified by numerous studies (Marie-Etancelin et al., 2001), leading to the development of appraisal methods of the udder which are being implemented in several breeding programs to improve udder morphology for milkability. On the other hand, a lack of knowledge on kinetics of the milk emission during machine milking still persists, mainly as a consequence of the difficulty of a large scale recording. Recently an automatic device able to follow individual kinetics of milk emission, developed by INRA (Ricard et al., 1995), was installed at the IZCS. The first purpose of this work was modelling the average shape of milk emission curves during machine milking by fitting an appropriate polynomial. Furthermore, since previous analysis showed that milk flow parameters, such as maximum or average milk flow, manifested an individual variability (Carta et al., 2000), it was investigated whether this variability is also present in the shape of individual curves. With this goal a linear mixed model with random regression coefficients was implemented

Types et domaines de prescriptions parentales : différences de sexe et effet sur la prise de risque chez l'enfant préscolaire

International audienceLes garçons et les filles se différencient très tôt en termes de comportements à risque accidentel (Granié, 2007, 2010), ce qui peut en partie être expliqué par une différence de sexe en termes de conformité et d'internalisation des règles de prudence (Granié, 2007, 2009), relié au niveau de féminité (Granié, 2009). L'internalisation des règles sociales dépend en partie du type de prescription parentale (Hoffman, 1970), notamment en termes d'interdits et d'obligations (Beauvois, Dubois, Py & Somat, 1995). Les premières prescriptions parentales prennent la forme d'interdits (Gralinski & Kopp, 1993), relevant des domaines prudentiel et moral (préservation du bien-être physique et psychologique de soi et d'autrui) (Smetana, 1997). Ces interdits, plus nombreux à l'égard des filles (Beauvois, Dubois, Py & Somat, 2000), s'accompagnent de pratiques plus inductives, qui favorise la conformité de l'enfant (Beauvois, Dubois, Py & Somat, 1995 ; Hoffman, 1970). Cette étude a pour objectifs d'analyser l'influence du sexe et du niveau de féminité de l'enfant sur les domaines et les types de prescriptions parentales, sur le niveau de conformité de l'enfant et l'effet de ces différentes variables sur ses comportements à risque accidentel. Soixante-huit parents (30 hommes et 38 femmes) d'enfants de 3 à 6 ans (35 garçons et 33 filles) ont participé à l'étude. Chaque parent a renseigné : - l'IRQEP (Gralinski & Kopp, 1993) permettant de mesurer l'importance déclarée de 55 prescriptions (30 interdits et 25 obligations) relevant de 4 domaines sociaux : moral (10 items), prudentiel (22), conventionnel (17), personnel (4) et le niveau de conformité de l'enfant sur ces prescriptions - l'IBC (Speltz, Gonzales, Sulzbacher, & Quan, 1990), contenant 24 items mesurant la fréquence de comportements potentiellement accidentogènes - le PSAI destiné à mesurer l'adhésion aux stéréotypes de sexe chez l'enfant préscolaire (Golombok et Rust, 1993a, 1993b) - l'échelle ASS (Granié, 2008) afin de contrôler l'adhésion aux stéréotypes de sexe des parents. Les résultats permettent de vérifier les hypothèses de l'étude. Dès la petite enfance, les filles sont plus contraintes dans leur comportement que les garçons et sont plus conformes aux prescriptions parentales. L'adhésion aux stéréotypes féminins amène une plus grande conformité, notamment dans les domaines prudentiels et moraux, ces deux éléments engendrant une moindre prise de risque chez l'enfant

Evénement culturel et dynamiques territoriales : le festival de jazz à Marciac

Notre propos concerne des formes de rituels collectifs, de rites, de cérémonies interprétées comme maintien-construction de lien social et de nouvelles formes de sociabilités dans les campagnes c'est-à-dire de vie sociale, culturelle et économique en émergence. Nous considérons ici la culture comme « levain » de développement durable des territoires. L'exemple du festival de jazz à Marciac est pertinent car il renvoie à une pratique culturelle territorialisée

Response to somatic cell count-based selection for mastitis resistance in a divergent selection experiment in sheep

A divergent selection experiment in sheep was implemented to study the consequences of log-transformed somatic cell score (SCS)-based selection on resistance to natural intramammary infections. Using dams and progeny-tested rams selected for extreme breeding values for SCS, we created 2 groups of ewes with a strong divergence in SCS of approximately 3 genetic standard deviations. A survey of 84 first-lactation ewes of both the High and Low SCS lines indicated favorable responses to SCS-based selection on resistance to both clinical and subclinical mastitis. All clinical cases (n = 5) occurred in the High SCS line. Additionally, the frequency of chronic clinical mastitis,as detected by the presence of parenchymal abscesses, was much greater in the High SCS line (n = 21) than in the Low SCS line (n = 1). According to monthly milk bacterio-logical examinations of udder halves, the prevalence of infection was significantly greater (odds ratio = 3.1) in the High SCS line than in the Low SCS line, with predicted probabilities of 37 and 16%, respectively. The most frequently isolated bacteria responsible for mastitis were staphylococci: Staphylococcus auricularis(42.6% of positive samples), Staphylococcus simulans, Staphylococcus haemoliticus, Staphylococcus xylosus, Staphylococcus chromogenes, Staphylococcus lentus, Staphylococcus warneri, and Staphylococcus aureus. The incidence of positive bacteriology was greater in the High SCS line (39%) than in the Low SCS line (12%)at lambing, indicating that High SCS line ewes were especially susceptible to postpartum subclinical mastitis. Negativation of bacteriological results from one sampling time point to the next was markedly different between lines after weaning (e.g., 41 and 84% in the High and Low SCS lines, respectively). This result was consistent with differences in the duration of infection, which was much greater in the High SCS line compared with the Low SCS line. Finally, ewes from the High SCS line consistently had greater SCS in positive milk samples than did ewes from the Low SCS line (+2.04 SCS, on average), with an especially large difference between lines during the suckling period (+3.42 SCS). Altogether, the preliminary results suggest that the better resistance of Low SCS line ewes, compared with High SCS line ewes, was principally characterized by a better ability to limit infections during the peripartum period, to eliminate infections during lactation, and quantitatively to limit the inflammation process and its clinical consequences

Territoires prescrits, territoires vécus : inter-territorialité au cœur des recompositions des espaces ruraux

Programme provisoire Mercredi 25 octobre 09h00-10h00 : Accueil des participants 10h00-10h30 : Ouverture et présentation du colloque - Brigitte LAQUIÈZE - Jean-Luc MAYAUD, Marie-Claude CASSÉ et Anne-Marie GRANIÉ 10h30-12h30 : Conférences inaugurales - Jacqueline MANGIN - Bernard KAYSER 12h30-14h00 : Déjeuner 14h00-16h00 : Regards croisés - Marie-Vic OZOUF-MARIGNIER, Vivre au pays : la préhistoire d'un slogan (XIXe-XXe siècles) - Maryvonne BODIGUEL et Jean-Luc BODIGUEL, Pourq..

EM-REML estimation of covariance parameters in Gaussian mixed models for longitudinal data analysis

This paper presents procedures for implementing the EM algorithm to compute REML estimates of variance covariance components in Gaussian mixed models for longitudinal data analysis. The class of models considered includes random coefficient factors, stationary time processes and measurement errors. The EM algorithm allows separation of the computations pertaining to parameters involved in the random coefficient factors from those pertaining to the time processes and errors. The procedures are illustrated with Pothoff and Roy's data example on growth measurements taken on 11 girls and 16 boys at four ages. Several variants and extensions are discussed

A quasi-score approach to the analysis of ordered categorical data via a mixed heteroskedastic threshold model

This article presents an extension of the methodology developed by Gilmour et al. [19], for ordered categorical data, taking into account the heterogeneity of residual variances of latent variables. Heterogeneity of residual variances is described via a structural linear model on log-variances. This method involves two main steps: i) a ’marginalization’ with respect to the random effects leading to quasi-score estimators; ii) an approximation of the variance-covariance matrix of the observations which leads to an analogue of the Henderson mixed model equations for continuous Gaussian data. This methodology is illustrated by a numerical example of footshape in sheep.Cet article présente une extension de la méthodologie développée par Gilmour et al. [19] dans le cas de variables qualitatives ordonnées, prenant en compte l’hétérogénéité des variances résiduelles des variables latentes. L’hétérogénéité des variances résiduelles est décrite par un modèle linéaire structurel sur les logarithmes des variances. Cette méthode comprend deux étapes principales : i) une « marginalisation » par rapport aux effets aléatoires qui conduit, grâce aux équations de quasi-score, à l’estimation des paramètres ; ii) une approximation de la matrice de variance-covariance des observations qui aboutit à un système analogue aux équations du modèle mixte d’Henderson dans le cas de variables continues gaussiennnes. Cette méthodologie est illustrée par un exemple sur la forme des pieds chez le mouton

Sex and Age Differences in the Endorsement of Sex Stereotypes Associated with Driving

Sex and age differences are particularly pronounced in car accidents. Current psychological research is exploring the relationship between risky driving and compliance with sex stereotypes, notably conformity with social expectations concerning masculinity. Some studies have already shown that sex stereotypes associated with driving (SSAD) may influence driving behaviors. The aim of this research was to explore the participants' sex and age differences in SSAD endorsement. A questionnaire was developed and validated on four dimensions of SSAD: male's driving skills and female's compliance with traffic rules, courtesy behind the wheel, and risk avoidance in driving. SSAD endorsement was measured for 291 licensed drivers from 18 to 64 years of age. Results revealed that females endorsed the female's risk avoidance stereotype more (p < .05), whereas males endorsed the male drivers (driving skills) stereotype more (p < .05). Results also revealed that the endorsement of male's driving skills decreases with age (p < .01) and the endorsement of female's courtesy increases with age among all participants (p = .01), while the endorsement of female's compliance with traffic rules increases with age only among female participants (p < .05). The results are discussed in terms of in-group/out-group relations and sex and age differences.Les différences de sexe et d'âge sont particulièrement prononcées dans des accidents routiers. La recherche psychologique actuelle explore la relation entre la conduite dangereuse et la conformité aux stéréotypes de sexe, notamment la conformité avec les attentes sociales concernant la masculinité. Certaines études ont déjà montré que les stéréotypes de sexe associés à la conduite (SSAD) peuvent influencer les comportements de conduite. L'objectif de cette recherche est d'explorer les différences de sexe et d'âge dans l'adhésion aux SSAD. Un questionnaire a été élaboré et validé sur les quatre dimensions de la SSAD: la compétence de conduite des hommes et la conformité avec les règles routières, la courtoisie au volant, et l'évitement des risques dans la conduite des femmes. L'adhésion aux SSAD a été mesurée chez 291 participants de 18 à 64 ans titulaires du permis de conduire. Les résultats ont révélé que les femmes adhèrent plus au le stéréotype de la femme évitant le risque (

Genetic parameters for first lactation dairy traits in the Alpine and Saanen goat breeds using a random regression test-day model

International audienceAbstractBackgroundRandom regression models (RRM) are widely used to analyze longitudinal data in genetic evaluation systems because they can better account for time-course changes in environmental effects and additive genetic values of animals by fitting the test-day (TD) specific effects. Our objective was to implement a random regression model for the evaluation of dairy production traits in French goats.ResultsThe data consisted of milk TD records from 30,186 and 32,256 first lactations of Saanen and Alpine goats. Milk yield, fat yield, protein yield, fat content and protein content were considered. Splines were used to model the environmental factors. The genetic and permanent environmental effects were modeled by the same Legendre polynomials. The goodness-of-fit and the genetic parameters derived from functions of the polynomials of orders 0 to 4 were tested. Results were also compared to those from a lactation model with total milk yield calculated over 250 days and to those of a multiple-trait model that considers performance in six periods throughout lactation as different traits. Genetic parameters were consistent between models. Models with fourth-order Legendre polynomials led to the best fit of the data. In order to reduce complexity, computing time, and interpretation, a rank reduction of the variance covariance matrix was performed using eigenvalue decomposition. With a reduction to rank 2, the first two principal components correctly summarized the genetic variability of milk yield level and persistency, with a correlation close to 0 between them.ConclusionsA random regression model was implemented in France to evaluate and select goats for yield traits and persistency, which are independent i.e. no genetic correlation between them, in first lactation