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International audience

International audience; The breeding programs of small ruminants have successively included in their breeding objectivesefficiency-related traits and then traits related with resistance to disease and udder morphology. There isnow an increasing willingness to select for resilience or rusticity related traits. This is due to a growingconcern in reducing the inputs, in anticipating the global warming consequences and keeping in line withthe agroecology demand. This project studied two traits frequently highlighted by the stakeholders:functional longevity and milk yield persistency. For each trait, we assessed the genetic parameters,estimated the genetic correlations between traits and calculated breeding values. Additionally, apromising approach of persistency, based on valorisation of test-days and lactation curves, has beenexplored in goats. The results showed that selecting for functional longevity and persistency of thelactation is possible in small ruminants. The technical and economic assessment also underlined that itwas desirable, especially when considering the breeders income. In order to anticipate and better pilotthe genetic choices, an observatory of the culling causes of reproducers was implemented in dairy sheep and goats and in meat sheep, on an experimental basis. Its feasibility was assessed with the view toextend it on a larger scale. A first hierarchy of the culling causes was established and specificationsproposed for a more massive deployment.; Les schémas de sélection des petits ruminants ont successivement intégré dans leur objectif de sélectiondes caractères de production, puis des caractères fonctionnels, notamment de résistance aux maladieset de morphologie de la mamelle pour les animaux laitiers. Aujourd’hui, la volonté de sélectionner descaractères d’adaptation et de rusticité est croissante en ovins et caprins, dans un contexte de réductiondes intrants, d’accroissement des contraintes agro-environnementales et de réchauffement climatique.Le projet s’est attaché à étudier deux caractères de rusticité fréquemment mis en exergue par les acteursde la sélection : la longévité fonctionnelle et la persistance laitière. Pour chacun des caractères, lesparamètres génétiques ont été estimés, les corrélations entre caractères calculés et des valeursgénétiques produites. En outre, une approche de la persistance, riche de promesse, basée sur lavalorisation des contrôles élémentaires et des courbes de lactation, a été explorée en caprins. Lesrésultats montrent que la sélection génétique de la longévité fonctionnelle et de la persistance laitière estpossible en petits ruminants. L’évaluation technico-économique a montré qu’elle était souhaitable, ycompris au regard du revenu de l’éleveur. Afin d’anticiper puis de piloter les choix génétiques mais aussisanitaires, un observatoire des causes de sortie des reproducteurs a été mis en place dans les troisfilières à titre expérimental et sa faisabilité évaluée pour une utilisation à plus grande échelle. Ainsi unepremière hiérarchisation des causes de sortie a été établie et un cahier des charges proposé pour undéploiement plus massif.

International audience

International audience; The aims of this study were to investigate variation in content of androstenone (AND), skatole (SKA), and indole (IND), quantified in adipose tissue of intact male pigs at 160 d of age (105 kg BW) and 220 d of age (155 kg BW), to estimate genetic parameters and to investigate the genetic relationships for AND, SKA, IND, and growth traits. A sample of adipose tissue was collected in vivo, using a biopsy device, from the neck of 500 intact males at the 2 ages and at slaughter from the ham of 100 of the investigated animals. Backfat depth was measured at 220 d of age, whereas BW was recorded at each sampling. Quantification of AND, SKA, and IND was performed by HPLC with fluorescence detection. Estimates of genetic parameters were obtained through Bayesian analyses after logarithmic transformations of original measures. Contents of boar taint compounds (BTC) measured at 220 d were higher than those at 160 d of age. Correlations between contents of BTC in backfat and ham fat ranged from 0.7 (IND) to 0.88 (SKA). Medium-high h were estimated for BTC at both ages, but estimates at 220 d (0.58, 0.60, and 0.69 for AND, SKA, and IND, respectively) were greater than those at 160 d. The genetic correlation between contents at 160 and 220 d of each BTC was positive, but the probability that such estimates were greater than 0.8 was very low, indicating that contents at 160 and 220 d were traits controlled by different genetic backgrounds. Different rankings were observed when breeding values for the content at 160 and 220 d of age were used to rank animals. As a consequence, performance testing programs for BTC should be based preferably on phenotypes measured at 220 d of age. Weak genetic correlations were observed between content of BT compounds and growth traits (BW, backfat depth, and daily gain from 160 to 220 d of age), indicating that selective breeding to reduce the risk of tainted pork is expected to exert trivial effects on growth performance and fat deposition. Results indicate that prevalence of BTC is high in mature and heavy pigs relative to young and light pigs. High heritability; positive genetic correlations between AND, SKA, and IND; and trivial effects on growth traits suggest that reduction of BTC through selective breeding is feasible and exploitable as an alternative to surgical castration also for pigs slaughtered at heavy BW.