7 research outputs found
Quantifying growth perturbations over the fattening period in swine via mathematical modelling
Analyse du déterminisme génétique de la caudophagie chez des femelles de la lignée Tai Zumu en fin d'engraissement
Cette Ă©tude porte sur la quantification des bases gĂ©nĂ©tiques de la caudophagie chez des femelles Tai Zumu. Le phĂ©notype mesurĂ© est la prĂ©sence de morsure(s) Ă la queue en fin dâengraissement, traduisant le fait que lâanimal nâa pas su se dĂ©fendre contre lâattaque de ses congĂ©nĂšres. Les objectifs sont de 1/ comparer les performances de croissance et dâadipositĂ© au contrĂŽle Ă 100kg entre femelles indemnes et femelles mordues Ă la queue, 2/ quantifier la contribution dâeffets gĂ©nĂ©tiques sociaux, qui sont liĂ©s aux gĂ©notypes des partenaires de groupe, Ă la variation phĂ©notypique du caractĂšre âmorduâ, et enfin 3/ estimer les effets de lâenvironnement sur lâexpression gĂ©nĂ©tique de ce caractĂšre sous forme dâinteractions gĂ©nĂ©tique-environnement (GxE). La prĂ©sence de morsure(s) a Ă©tĂ© enregistrĂ©e sur 33266 cochettes dans les trois Ă©levages de sĂ©lection de la lignĂ©e. La prĂ©valence variait entre 2,8% et 10,8% selon lâĂ©levage. Ceux-ci diffĂšrent par les caractĂ©ristiques des groupes (ex. taille, nombre de mĂ©langes) et le mode dâalimentation en engraissement. Les modĂšles dâanalyse tenaient compte dâun effet gĂ©nĂ©tique direct seul ou avec un effet gĂ©nĂ©tique social. Les modĂšles ont Ă©tĂ© appliquĂ©s Ă la population globale des trois Ă©levages et Ă chaque Ă©levage sĂ©parĂ©ment. Les effets gĂ©nĂ©tiques sociaux contribuent Ă plus de 80% de la variance hĂ©ritable. Leur prise en compte permet dâexpliquer 40 Ă 80% de la variation phĂ©notypique contre seulement 6 Ă 8% avec un modĂšle direct. Les diffĂ©rences entre Ă©levages de classement des verrats connecteurs selon leurs valeurs gĂ©nĂ©tiques, indiquent lâexistence de fortes GxE puisque leurs corrĂ©lations de rang sont non diffĂ©rentes de 0. Bien que la part de variance gĂ©nĂ©tique directe du caractĂšre soit trĂšs faible, une sĂ©lection contre la caudophagie est possible. Inclure des effets gĂ©nĂ©tiques sociaux permet de mieux quantifier la variation hĂ©ritable et leur prise en compte dans les schĂ©mas augmenterait la rĂ©ponse Ă la sĂ©lection contre ce comportement dĂ©viant.This study focusses on quantification of the genetic basis of tail-biting in Tai Zumu females. The phenotype under measure was the presence of tail bite(s) at the end of the fattening period, reflecting that the animal was unable to defend itself from groupmatesâ attacks. The objectives were to (1) compare the growth and leanness performance at the monitoring at 100 kg between non-bitten females and bitten females; (2) quantify the contribution of social genetic effects, which depend on the genotypes of groupmates, to the phenotypic variation of the trait âbittenâ; and (3) estimate the effect of the environment on the genetic expression of this trait as interactions between genetics and environment (GxE). The presence of tail bite(s) was recorded on 33,266 gilts from three nucleus herds. The prevalence of tail bites varied from 2.8% to 10.8% among herds that differed according to the groupsâ characteristics (e.g., size, number of mixings) and feeding system during fattening. The models for analyses considered single direct genetic effects or also social genetic effects. Models were applied to the entire population including the three nucleus herds and to each herd taken separately. Social genetic effects contributed to more than 80% of total heritable variance, which equalled 40-80% of phenotypic variation, whereas only 6-8% was explained with a direct model. Differences in the ranking of connecting sires between herds according to their breeding values yielded rank correlations not different from zero, indicating strong GxE. Selection against tailbiting is possible even though the direct genetic contribution for this trait is low. Considering social genetic effects improves quantification of heritable variation, and accounting for them in breeding schemes would increase response to selection against this deviant behaviour
Genetics of tail-biting receipt in gilts from the Tai Zumu line
Tail-biting (TB) receipt was recorded at the end of the fattening period on 33,266 gilts of the Tai Zumu population, that were raised in groups of 6 to 20 females. This study aimed at quantifying the contribution of social genetic effects to TB receipt, and at assessing the importance of the environment on the genetic expression of this behaviour (GxE). Models for TB receipt included the fixed effects of number of group mates, (herd)-year-month, and the random effects of group, litter, and direct and social additive genetic effects. The model was applied to the complete gilt population and separately to 2 sub-populations, corresponding to 2 of the 3 nucleus herds raising that line, where TB receipt frequency differed and was high enough (>5%). TB receipt was analysed as a linear trait, following a normal distribution with the restricted likelihood methodology applied to an animal model. Social genetic effects contributed 81% to 93% of total heritable variance, which equalled 40 to 80% of phenotypic variation. The variance components varied between herds. The analysis of sire by environment interactions indicated re-ranking of sires between the 2 nucleus herds, according to both their direct and total breeding values
Towards the characterisation of animal robustness by dynamic energy allocation indicators in fattening pigs
International audienceThe objectives of this study were to investigate the possibility of characterising animalrobustness by using indicators based on the dynamics of energy allocation of the animal andto determine their genetic parameters. A total of 2 140 pigs, from the Piétrain NN Françaisline, were raised at the AXIOM boar testing station. This farm was equipped with automaticfeeding system, recording individual weight and feed intake at each visit. We used a dynamiclinear regression model to characterize the evolution of the allocation factor ( αt) betweencumulative net energy available, estimated from feed intake, and cumulative weight gainduring fattening period. The variance of α t, that could be interpreted as an indicator of theresponse of the animal to perturbations/stress, showed moderate heritability (0.27 ±0.08). Ourperspective is to further decompose the allocation factor into components to bettercharacterise the robustness phenoty
Disentangling the dynamics of energy allocation to provide a proxy of robustness in fattening pigs
International audienceAbstract Background There is a growing need to improve robustness characteristics in fattening pigs, but this trait is difficult to phenotype. Our first objective was to develop a robustness proxy on the basis of modelling of longitudinal energetic allocation coefficient to growth for fattening pigs. Consequently, the environmental variance of this allocation coefficient was considered as a proxy of robustness. The second objective was to estimate its genetic parameters and correlation with traits under selection as well with phenotypes routinely collected on farms. A total of 5848 pigs, from PiĂ©train NN paternal line, were tested at the AXIOM boar testing station (Azay-sur-Indre, France) from 2015 to 2022. This farm was equipped with automatic feeding system, recording individual weight and feed intake at each visit. We used a dynamic linear regression model to characterize the evolution of the allocation coefficient between cumulative net energy available, estimated from feed intake, and cumulative weight gain during fattening period. Longitudinal energetic allocation coefficients were analysed using a two-step approach, to estimate both its genetic variance and the genetic variance in the residual variance, trait LSR. Results The LSR trait, that could be interpreted as an indicator of the response of the animal to perturbations/stress, showed low heritability (0.05±0.01). The trait LSR had high favourable genetic correlations with average daily growth (â0.71±0.06) and unfavourable with feed conversion ratio (â0.76±0.06) and residual feed intake (â0.83±0.06). The analysis of the relationship between estimated breeding values (EBV) LSR quartiles and phenotypes routinely collected on farms shows the most favourable situation for animals from quartile with the weakest EBV LSR, i.e ., the most robust. Conclusions These results show that selection for robustness based on deviation from energetic allocation coefficient to growth can be considered in breeding programs for fattening pigs
IntĂ©rĂȘt des performances de truies croisĂ©es pour la sĂ©lection en race pure de caractĂšres de reproduction de la lignĂ©e maternelle Large-White
51. JournĂ©es de la Recherche Porcine, 5 et 6 fĂ©vrier 2019, Paris, p. 309-314,IntĂ©rĂȘt des performances de truies croisĂ©es pour la sĂ©lection en race pure de caractĂšres de reproduction de la lignĂ©e maternelle Large-White. 51. JournĂ©es de la Recherche Porcin
Ăvaluation de la pubertĂ© de cochettes Landrace français et indentification de facteurs de variation
International audienceWhile insemination at first estrus is not recommended, most studies agree on the benefits of early puberty, both for reproductive performance and sow longevity. In the swine population in France, sexual maturity is expected at ca. 200 days of age. Although age at puberty is crucial information, it is not recorded on farms. Since selection for low boar taint influences male puberty, it raises questions about its potential side effects on female reproductive ability. This study was carried out as part of a project that assessed impacts of selection against boar taint on the reproduction of Landrace females. The sexual maturity of 1878 gilts at ca. 200 days of age was evaluated on five farms using quantitative plasma progesterone analysis in two blood samples taken 10 days apart. Cutoff values of 2.5 or 5.0 ng/mL gave similar estimates of 19% immature gilts, with a large variation among farms (8-49%). Insemination was not performed for 4% of gilts, 9% were re-inseminated during the first cycle and 15% did not farrow. The rate of earlyreproduction difficulties varied greatly among farms. The influence of immaturity at 200 days was generally low, with a large farm effect. Further investigation is required to analyze long-term effects of late puberty