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Dissecting total genetic variance into additive and dominance components of purebred and crossbred pig traits

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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

2019

Validation européenne de la procédure française de détermination par tomographie à rayons X de la nouvelle teneur en muscle des porcs

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Gérard Daumas et al., 52e Journées de la Recherche Porcine (FRA), 4 et 5 février 2020, poster

Un nouveau règlement de l’UE sur la classifi cation des carcasses s’applique à compter de juillet 2018. La nouvelle référence pour calibrer les méthodes de classifi cation des porcs est un pourcentage de viande maigre basé sur la dissection manuelle totale (TMCdis) d’une demi-carcasse. La dissection manuelle peut être remplacée par une procédure sans biais de tomodensitométrie (RX). Daumas et Monziols (2018) ont calibré une méthode RX simple, précise et robuste, afi n de la rendre utilisable au niveau international, au moins en Europe. L’objectif de l’étude est de valider cette procédure lors d’un essai d’autorisation des méthodes de classement en Lituanie.

PDF icon Gérard Daumas et al., 52e Journées de la Recherche Porcine (FRA), 4 et 5 février 2020, poster
2020

Validation européenne de la procédure française de détermination par tomographie à rayons X de la nouvelle teneur en muscle des porcs

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Gérard Daumas et al., 52e Journées de la Recherche Porcine (FRA), 4 et 5 février 2020, p. 55-56, poster

Poster.

Un nouveau règlement de l'UE sur la classification des carcasses s'applique à compter de juillet 2018. La nouvelle référence pour calibrer les méthodes de classification des porcs est un pourcentage de viande maigre basé sur la dissection manuelle totale (TMCdis) d'une demi-carcasse. La dissection manuelle peut être remplacée par une procédure de tomodensitométrie sans biais (RX). Daumas et Monziols (2018) ont calibré une méthode de tomodensitométrie simple, précise et robuste afin de la rendre utilisable au niveau international au moins en Europe. L’objectif de l’étude est de valider cette procédure de tomodensitométrie par un essai d'autorisation des méthodes de classement en Lituanie.

ENG

European validation of the French X-ray tomography procedure to determine new muscle content of pigs

Poster.

Since July 2018, the new benchmark for calibrating pig classification methods is muscle content based on total dissection of a halfcarcass (LMPdis). Manual dissection can be replaced by an unbiased X-ray tomography (CT) procedure. The purpose of this study was to validate the French procedure in Lithuania to make it usable at least in Europe. The CT procedure was initially calibrated with 29 French pork half-carcasses measured in 2008. The same CT and dissection procedures were applied to 12 Lithuanian half-carcasses sampled in 2018 as part of the approval of new classification methods of pork carcasses. A regression model was fitted between LMPdis and the CT LMP (LMPct). The intercept was not significant. For the calibration dataset, the slope of the regression was estimated at 0.965 and its 95% confidence interval (95CI) at [0.960, 0.970]. For the validation dataset, the slope of the regression was estimated at 0.967 and its 95CI at [0.954, 0.980]. The 95CI of the validation sample included the 95CI of the calibration sample, thus showing no statistical difference between the two slopes. The CT procedure developed by IFIP in France has been validated successfully in Lithuania for the approval of new national methods for classifying pork carcasses. From now on, this unbiased procedure should be able to be used in any EU Member State without further national dissection. In addition, this procedure can be used effectively for zootechnical trials without the risk of within-treatment bias.

PDF icon Gérard Daumas et al., 52e Journées de la Recherche Porcine (FRA), 4 et 5 février 2020, p. 55-56, poster
2020

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