Génétique

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Le recueil des JRP permet la diffusion rapide des résultats de la recherche francophone sous forme d’articles de 6 pages ou 2 pages, comprenant tous un résumé en anglais.

Panorama interactif des études Ifip financées par FranceAgriMer pour le Pôle viandes et charcuteries de 2010 à 2018.

Le document offre un accès facilité aux résultats de chaque étude par un lien direct à une fiche synthétique.

Panorama interactif des études Ifip financées par Inaporc pour le Pôle viandes et charcuteries de 2010 à 2018.

Le document offre un accès facilité aux résultats de chaque étude par un lien direct à une fiche synthétique.

Pauline Brenaut, Porc Mag (FRA), 2019, n° 547, novembre, p. 27

Basé sur de l'imagerie, le projet Pic'Let (PICture of pig LET) a pour objectif de développer un capteur capable de détecter précocement les porcelets immatures. Présentation.

Mohammadpanah M (Shahid Bahonar University of Kerman, Iran) et al., 70th Annual meeting of the European Federation of Animal science (EAAP), 26-30 août 2019, Ghent, Belgique, p. 291, poster

In pig crossbreeding programs, genetic evaluation has been based predominantly on purebred data accounting only for additive genetic effects, whereas improving crossbred performance is the ultimate goal. Theoretically, a combined crossbred and purebred selection method is advised if genetic correlation between purebred and crossbred populations differ from unity. If dominance effects are large enough, assortative mating strategies can enhance the total genetic values of the offspring. Hence, estimates of genetic parameters for purebreds and crossbreds are needed to assess the best selection crossbreeding scheme strategies. In this study, additive and dominance genetic variance components and additive and dominance genotypic correlations between a Piétrain and a Piétrain × Large White populations were estimated for backfat thickness (BFT). A total of 607 purebreds and 620 crossbred BFT records were analysed with a genotypic bivariate model that included hot carcass weight and inbreeding coefficient as covariates, an additive and a dominance genotypic effects, and a pen nested within batch random effect. Genetic parameters were estimated with EM-REML plus an additional iteration of AIREML to obtain the asymptotic standard deviations of the estimates. The additive genotypic correlation between purebreds and crossbreds was high, 0.82, indicating that the genetic progress attained in the purebreds can mostly be transferred to the crossbreds. Dominance genetic variance represented about 10% of the BFT phenotypic variance in both populations, suggesting that assortative matings could slightly enhance both purebred and crossbred performances. However, the underlying genetic mechanisms responsible for the dominance effects could differ between populations since dominance genotypic correlation was 0.49.

Vanille Déru (INRA/ France Génétique Porc) et al., 70th Annual meeting of the European Federation of Animal science (EAAP), 26-30 août 2019, Ghent, Belgique, p. 415

The use of diets with dietary fibres from alternative feedstuffs less digestible for pigs is a solution considered to limit the impact of increased feed costs on pig production. This study aimed at determining the impact of an alternative diet with fibres on individual digestive efficiency coefficients, and to estimate their heritabilities and genetic correlations with other production traits. A total of 480 Large White pigs were fed a high fibre diet (FD) and 547 of their sibs were fed a conventional diet (CO). For each animal, digestibility coefficients (DC) of energy, organic matter, and nitrogen were predicted from faeces samples analysed with near infrared spectrophotometry.

Individual daily feed intake (DFI), average daily gain (ADG), feed conversion ratio (FCR) were recorded as well as lean mean percentage (LMP), carcass yield (CY) and meat quality traits. The FD pigs had significantly lower DC than CO pigs (-5 to 6 points). The DC were moderately to highly heritable, with heritabilities ranging from 0.41±0.14 to 0.50±0.15 in CO, and from 0.62±0.17 to 0.70±0.17 in FD. Genetic correlations between DC and ADG (from -0.65 to -0.52), FCR (from -0.75 to -0.33), and DFI (from -0.83 to -0.57) were high and negative in both diets. The DC were slightly unfavourably correlated with CY (from -0.24 to -0.11) and favourably correlated with LMP (from 0.03 to 0.29). Genetic correlations were generally unfavourable with meat quality traits (from -0.75 to 0.09). Genetic correlations of DC between diets were close to 1, so no interaction between feed and genetics could be evidenced for these traits. To conclude, DC measured in farm conditions are interesting criteria for selection to account for animal digestive capacity, due to moderate to high heritabilities and high genetic correlations with FCR.

However, according to these first results, it would have to be selected together with carcass yield and meat quality to avoid adverse genetic trends on the latter traits.

Llibertat Tusell et al., Animal, 23 mai 2019, 11 pages

The partition of the total genetic variance into its additive and non-additive components can differ from trait to trait, and between purebred and crossbred populations. A quantification of these genetic variance components will determine the extent to which it would be of interest to account for dominance in genomic evaluations or to establish mate allocation strategies along different populations and traits. This study aims at assessing the contribution of the additive and dominance genomic variances to the phenotype expression of several purebred Piétrain and crossbred (Piétrain × Large White) pig performances. A total of 636 purebred and 720 crossbred male piglets were phenotyped for 22 traits that can be classified into six groups of traits: growth rate and feed efficiency, carcass composition, meat quality, behaviour, boar taint and puberty. Additive and dominance variances estimated in univariate genotypic models, including additive and dominance genotypic effects, and a genomic inbreeding covariate allowed to retrieve the additive and dominance single nucleotide polymorphism variances for purebred and crossbred performances. These estimated variances were used, together with the allelic frequencies of the parental populations, to obtain additive and dominance variances in terms of genetic breeding values and dominance deviations. Estimates of the Piétrain and Large White allelic contributions to the crossbred variance were of about the same magnitude in all the traits. Estimates of additive genetic variances were similar regardless of the inclusion of dominance. Some traits showed relevant amount of dominance genetic variance with respect to phenotypic variance in both populations (i.e. growth rate 8%, feed conversion ratio 9% to 12%, backfat thickness 14% to 12%, purebreds-crossbreds). Other traits showed higher amount in crossbreds (i.e. ham cut 8% to 13%, loin 7% to 16%, pH semimembranosus 13% to 18%, pH longissimus dorsi 9% to 14%, androstenone 5% to 13% and estradiol 6% to 11%, purebreds-crossbreds). It was not encountered a clear common pattern of dominance expression between groups of analysed traits and between populations. These estimates give initial hints regarding which traits could benefit from accounting for dominance for example to improve genomic estimated breeding value accuracy in genetic evaluations or to boost the total genetic value of progeny by means of assortative mating.

https://www.feed-a-gene.eu/sites/default/files/documents/tusell_2019_JAS_dissecting_total_genetic_variance_into_additive_and_dominance_components_of_purebred_and_crossbred_pig_traits.pdf

Marie-José Mercat, Réussir Porc/ Tech Porc (FRA), 2019, n° 270, juillet-août, p. 44-45

Des leviers génétiques existent pour sélectionner des animaux résistants à certains variants d’agents infectieux comme E. coli.

Mais une résistance globale aux maladies, ou simplement à tous les variants d’E. coli, semble illusoire.

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