La fonte lipidique du foie gras à la cuisson

La connaissance des facteurs biologiques, zootechniques et technologiques ainsi que des mécanismes qui contrôlent le taux de fonte des foies gras à la cuisson est primordiale pour la maîtrise du rendement technologique des foies gras. En effet, le taux de fonte à la cuisson a des répercussions sur les qualités organoleptiques des foies gras et sur les performances des unités de production

Genetic analysis of milking ability in Lacaune dairy ewes

The milking ability of Lacaune ewes was characterised by derived traits of milk flow patterns, in an INRA experimental farm, from a divergent selection experiment in order to estimate the correlated effects of selection for protein and fat yields. The analysis of selected divergent line effects (involving 34 616 data and 1204 ewes) indicated an indirect improvement of milking traits (+17% for maximum milk flow and -10% for latency time) with a 25% increase in milk yield. Genetic parameters were estimated by multi-trait analysis with an animal model, on 751 primiparous ewes. The heritabilities of the traits expressed on an annual basis were high, especially for maximum flow (0.54) and for latency time (0.55). The heritabilities were intermediate for average flow (0.30), time at maximum flow (0.42) and phase of increasing flow (0.43), and low for the phase of decreasing flow (0.16) and the plateau of high flow (0.07). When considering test-day data, the heritabilities of maximum flow and latency time remained intermediate and stable throughout the lactation. Genetic correlations between milk yield and milking traits were all favourable, but latency time was less milk yield dependent (-0.22) than maximum flow (+0.46). It is concluded that the current dairy ewe selection based on milk solid yield is not antagonistic to milking ability

Pyroséquençage pour le développement d'EST et de SNP aviaires

Le but du programme est de combler les déficits en marqueurs observés pour trois espèces aviaires : la caille, le canard et la poule. La stratégie choisie est l'obtention, à partir de plusieurs individus de lignées d'intérêt, de SNP (Single Nucleotide Polymorphism, polymorphisme d'un nucléotide) par une nouvelle technologie de séquençage à haut débit (séquenceur 454 GS-FLX, Roche). Nous séquençons des représentations réduites du génome, en sélectionnant d'une part des fragments de restriction d'ADN génomique - les mêmes chez tous les individus - et d'autre part les transcrits qui représentent globalement la partie du génome correspondant aux gènes exprimés. Ces expérimentations sont réalisées à partir d'échantillons d'ADN ou d'ARN issus d'individus de lignées à l'origine de croisements existants, pour chacune des trois espèces. Les données générées par plusieurs "runs" de séquence seront traitées in silico : contigage à haut débit, recherche de SNP, comparaison avec les banques de séquences connues...En plus de l'intérêt que représente la production d'un très grand nombre de SNP nouveaux, cette technologie devrait permettre de mieux séquencer les régions riches en (G+C) correspondant aux plus petits des microchromosomes pour lesquels il n'y a pas de séquence chez la poule. La comparaison des séquences des transcrits obtenues chez la caille et le canard avec la séquence du génome de la poule permettra d'établir une "cartographie virtuelle" des SNP obtenus, grâce à la grande conservation de synténie existant entre ces trois espèces

Influence du potentiel laitier sur les composantes de l'efficacité alimentaire de brebis Lacaune

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Genetic parameters along the near infra red spectra to predict melting rate of the duck fatty liver

International audienc

Breeding for the milk market: the French situation compared to the EU mediterranean countries

*INRA/SAGA Toulouse Diffusion du document : INRA/SAGA ToulouseInternational audienc

Quantitative genetics of feed efficiency in ducks

Given the worldwide diversity of duck production, genetics aspects of feed efficiency of ducks should be addressed depending on the production (broilers, layers, and “foie gras”) and on the genetic types (Muscovy duck, common duck, and their intergeneric cross mainly used in France for “foie gras” production after force-feeding, i.e. the mule duck). The two main criteria to characterize feed efficiency are the feed conversion ratio (FCR), computed as the ratio of food quantity divided by the output, and the residual feed intake (RFI) which is obtained through a multiple linear regression of feed intake by output and metabolic requirements. The former is a ratio, with undesirable statistic properties. In addition, it is uneasy to disentangle variations in net feed efficiency from variations in FCR due to production traits. The latter is supposed to be, at least phenotypically, independent from the constituent production traits. This is the reason why it gained popularity, even though it requires a thorough analysis of metabolic requirements, as in the overfed mule ducks, where the fat deposition capacity should not be impaired. In the literature, the values found for FCR depend on the genetic type and on the production: FCR≈2.5 at 12 wk. for male Muscovy and FCR >3.2 at 13 wk. for fatty mule ducks; FCR ≈ 1.9 at 42d for Pekin broilers; FCR ≈2.8 for layers. Usually RFI is moderately heritable (h²≈0.25 in layers; 0.3<h²<0.4 in Pekin broilers) and slightly more heritable than FCR. RFI heritability of fattened mule ducks needs to be refined. Genetic correlations between FCR and RFI vary between studies, from moderate (ρG=+0.34) to high (ρG=+0.99). Reliable assessment of individual feed intake is an issue. Development of RFID based automatic feeders greatly helped the improvement of feed efficiency in duck breeding programs. Such devices open the field for new studies, as they give access to feeding behavioral traits. They also allow for the joint modeling of trajectories for feed intake and production traits. Finally, as a complex trait, selection for feed efficiency should benefit from the availability of molecular tools

Efficacité alimentaire selon le potentiel laitier des brebis

National audienc