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While 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.

Seasonal variations in the climatic environment are known to decrease the reproductive performance of sows. The objectives of this study were to evaluate effects of seasonal variations on farrowing rate (FR) measured from commercial farm data and to produce equations to predict FR from outdoor temperature. The data used were extracted from the Technical Management of Sow Herds database (GTTT). This extraction contained 2,788,028 records (from 2002-2012) from 780 and 131 farms in France La Réunion Island, respectively. Climatic data were obtained from public weather stations of Météo France located within a 10 km radius from each farm. Our results confirmed seasonal variation in the FR, which was 2.2% and 3.5% lower in summer in France and La Reunion Island, respectively. This seasonal infertility was particularly high in primiparous sows. FR was influenced by high temperatures that occurred during a critical period of reproductive cycles identified from 3-30 and 5-20 days before the first mating of gilts and weaned sows, respectively. Binomial regressions were used to predict FR from the mean temperature measured during the critical period. Between 10 and 30°C, the risk of infertility increased by a mean of 4.2%, 8.4% and 4.9% for gilts, primiparous sows and multiparous sows respectively. The accuracy of predictions of risk of infertility was low for gilts and primiparous sows. For these animals, seasonal infertility is a multifactorial syndrome, which could explain the difficulty in accurately predicting FR from outdoor temperature only. For multiparous sows, the improved accuracy of the prediction equation allows it to be used it in a modeling approach., Les variations saisonnières de l’environnement climatique sont connues pour influencer négativement les performances de reproduction de la truie. Les objectifs de ce travail sont de caractériser, sur la base de données d’élevages commerciaux, les effets des variations saisonnières sur le taux de réussite à la saillie (TxSaillie) et de produire des équations reliant la température à la fertilité des truies. Les données utilisées ont été extraites de la base de données GTTT. Cette extraction contenait 2 788 028 enregistrements de saillie provenant de 780 élevages en France et 131 élevages à la Réunion entre 2002 et 2012. Les données climatiques provenaient des stations publiques de Météo France localisées à moins de 10 km des élevages. Nos résultats confirment la variation saisonnière du TxSaillie avec des réductions de 2,2 et 3,5% en période estivale, respectivement en métropole et à la Réunion. Cette infertilité saisonnière est particulièrement marquée chez les truies primipares. La période critique du cycle pour laquelle les effets de la température sur le TxSaillie sont les plus importants a été identifiée entre le 30ème et le 3ème jour et entre le 5ème au 20ème jour avant la première saillie, respectivement pour les cochettes et les truies. Des régressions binomiales ont été utilisées pour relier la réussite à la saillie à la température moyenne enregistrée pendant la période critique. Entre 10 et 30°C, le risque d’échec à la saillie augmente en moyenne de 4,2, 8,4 et 4,9%, respectivement pour les cochettes, les truies primipares et multipares. La précision des estimations du risque d’échec à la saillie est faible pour les cochettes et les truies primipares. Chez ces animaux, le caractère multifactoriel de l’infertilité saisonnière rend difficile la prédiction fiable du TxSaillie à partir de la température. Chez les truies multipares, l’amélioration de la capacité prédictive des équations rend possible leur utilisation en modélisation.

Our objective was to develop alternatives to hormones for estrus synchronization in gilts. Gilts exhibit a pre-puberty period with high urinary estrone concentration during which boar exposure could induce the first ovulation. We searched for salivary biomarkers of this period. Urine and saliva were collected on six 140-day-old gilts until puberty for estrone assay, metabolome and steroidome analysis. We identified 23 metabolites and 28 steroids in saliva. The concentration of 8 of them showed significant variations at the pre-puberty period, they were candidate biomarkers. Saliva was collected from 30 gilts exposed to a boar and subjected to estrus detection from 150 to 175 days of age. Metabolome and steroidome analyses allowed the identification of 33 metabolites and 29 steroids in saliva. Their concentrations were not significantly different between receptive and non-receptive gilts. Thus, we could not identify salivary biomarkers of the period of receptivity to the boar effect.

La castration des porcelets mâles a pour but de diminuer les risques de comportement agressif et d’éviter des défauts de qualité de viande. En effet, chez certains mâles entiers, l’androsténone (molécule produite dans les testicules) et le scatol (produit par les bactéries du tube digestif) s’accumulent dans le gras et donnent une odeur désagréable à la viande. Dans une perspective d’élevage de mâles entiers, une sélection contre l’accumulation d’androsténone dans le gras est envisagée, mais les éventuels effets négatifs sur la reproduction restent à analyser. L’objectif de l’étude est d’évaluer les relations entre l’accumulation d’androsténone dans le gras dorsal, la mise en place de la puberté chez les jeunes verrats, le comportement sexuel et les caractéristiques de la semence chez les verrats matures. Un phénotypage fin a été réalisé sur 114 verrats dans l’unité expérimentale INRA GenESI. Chaque verrat totalise jusqu’à 455 observations comprenant des mesures de production spermatique, des dosages d’androsténone et de scatol dans le gras dorsal et d’hormones plasmatiques (testostérone et œstradiol) à 180 jours et à 280 jours d’âge, des observations du comportement (débourrage, maintien de l’aptitude au prélèvement de semence et test de confiance vis-à-vis de l’homme) et des caractéristiques de semence. Des analyses multivariées ont été effectuées pour estimer les relations entre ces mesures. Les résultats suggèrent que l’œstradiol plasmatique peut servir de prédicteur de l’androsténone et qu’il n’y a pas de lien entre l’androsténone, les caractéristiques de la semence et le comportement sexuel des verrats., Male piglets are castrated to reduce the risk of aggressive behavior and improve meat quality. In some entire males, androstenone (from testes) and skatole (produced by the gut bacteria) accumulate in fat and give an unpleasant smell to the meat. Genetic selection against androstenone accumulation in back fat in entire males has been considered to overcome boar taint in carcasses, but possible side effects on reproductive traits have to be investigated. The objective of the study was to evaluate the relationship between androstenone accumulation in back fat, beginning of puberty, sexual behavior and semen characteristics in mature boars.To meet this objective, fine phenotyping of 114 boars was performed at the INRA GenESI experimental station. Each boar represented up to 455 observations, tests or samples, including concentrationsof androstenone and skatole in back fat, concentrations of hormones in blood at 180 and 280 days of age, behavioral observations (breaking, maintaining libido and test of confidence in humans) and semen characteristics. Multivariate analysis was performed to estimate the relationships between variables. Results suggest that plasma œstradiol may predict androstenone and that there was no relationship between androstenone, semen characteristics, and boar libido

International audience; Our objective was to develop alternatives to hormonal treatments to synchronize oestrus of gilts. Before puberty gilts exhibit a pre-puberty period during which boar exposure could induce and synchronize first ovulation. To develop practical non-invasive tools to identify this period and improve detection of the gilts to stimulate, we searched for salivary biomarkers of the pre-puberty period. Saliva samples were collected from 30 Large-White x Landrace crossbred gilts from 140 to 175 days of age. Gilts were exposed to a boar twice a day and subjected to oestrus detection from 150 to 175 days of age. Among the 30 gilts, 10 were detected in oestrus 4 to 7 days after introduction of the boar and were considered receptive to the boar effect, 14 were detected in oestrus more than 8 days after boar introduction, 6 did not show oestrus and were considered non-receptive. Saliva samples from 6 receptive and 6 non-receptive gilts were analysed for steroidome using GC-MS/MS and for metabolome using 1H-NMR spectroscopy. Four saliva samples per gilt were analysed: 26 days and 11 days before boar introduction (BI-26 and BI-11), the day of boar introduction (BI), 3 days later for receptive gilts (BI+3) or 7 days later for non-receptive gilts (BI+7). Data were analysed using repeated measures one-way ANOVA and orthogonal partial least squares discriminant analysis. Thirty steroids and 35 metabolites were detected in gilt saliva. The concentrations of 6 steroids were higher (P < 0.05) in receptive gilts than in non-receptive gilts at BI-26, BI-11 and BI. The concentration of 2 metabolites were lower (P < 0.05) in receptive gilts than in non-receptive gilts at BI-11. These candidates could be potential salivary biomarkers to detect receptive gilts. However, their low and variable concentrations in saliva require expensive analysis and limit their use in pig farms.

National audience; Our objective was to develop alternatives to hormonal treatments to synchronize oestrus of gilts. Before puberty, gilts experience a pre-puberty period during which boar exposure could induce and synchronize the first ovulation. To develop practical non-invasive tools to identify this period and improve detection of the gilts to stimulate, we searched for salivary biomarkers of the pre-puberty period. Saliva samples were collected from 30 Large-White x Landrace crossbred gilts from 140 to 175 days of age. Gilts were exposed to a boar twice a day and subjected to oestrus detection from 150 to 175 days of age. They were then slaughtered to ascertain puberty. Among the 30 gilts, 10 were detected in oestrus 4 to 7 days after introduction of the boar and were considered receptive to the boar effect, 14 were detected in oestrus more than 8 days after boar introduction, six did not show oestrus before slaughter and were considered non-receptive. Salivary steroidome analysis was performed for six receptive and six non-receptive gilts using gas chromatography coupled to tandem mass spectrometry. Four saliva samples per gilt were analysed: 26 days and 11 days before boar introduction (day0-26 and day0-11), the day of boar introduction (day0), 3 days later for receptive gilts (day0+3) or 7 days later for non-receptive gilts (day0+7). Saliva analysis detected 30 steroids. The concentrations of six of them were higher (P < 0.05) in receptive gilts than in non-receptive gilts at day0-26 (progesterone), day0-11 (3α5β20α-hexahydroprogesterone, 3β5α20β-hexahydroprogesterone, dehydroepiandrosterone, androstenediol) and day0 (3β5α-tetrahydroprogesterone). Their low and variable concentrations in saliva require expensive analysis and limit their use in pig farms. However, progesterone could be an interesting biomarker of the pre-puberty period.

National audience; Notre objectif à long terme est de développer des alternatives aux traitements hormonaux pour la synchronisation des oestrus des cochettes, notamment lors de l’entrée dans la première bande. Avant la puberté, les cochettes atteignent un stade physiologique de pré-puberté au cours duquel une stimulation externe est susceptible de déclencher la première ovulation. L’exposition au verrat, appelée effet mâle, pourrait favoriser le déclenchement et la synchronisation de la première ovulation, si elle est appliquée pendant cette période de pré-puberté. Cette pratique est peu utilisée en élevage, car le moment optimal et les modalités d’exposition au verrat ne sont pas clairement définis. L’objectif de cette étude est de rechercher des biomarqueurs de la phase de pré-puberté à l’aide de techniques non invasives. Les prélèvements de salive étant non invasifs et relativement faciles à mettre en place, notre étude porte sur la recherche de biomarqueurs salivaires de la phase de prépuberté. Le suivi de biomarqueurs salivaires permettra d’améliorer le repérage des femelles à stimuler et l'efficacité de l'effet mâle en élevage. L’étude a été réalisée pendant 5 semaines sur 6 cochettes Large-White de 140 jours d’âge jusqu’au premier œstrus. Un suivi échographique de l’utérus et des ovaires a permis de détecter la puberté. Des prélèvements individuels d’urine et un dosage de l’estrone urinaire ont permis de détecter la phase de pré-puberté, caractérisée par une augmentation des concentrations urinaires d’estrone. Des prélèvements individuels de salive ont été réalisés chaque semaine et analysés par GC/MS/MS (Gas Chromatography coupled to tandem Mass Spectrometry) pour obtenir un profil stéroïdien et par SRM (Spectroscopie à Résonance magnétique du proton) pour obtenir un profil métabolomique. Les analyses en SRM et GC/MS/MS ont permis de quantifier respectivement 23 métabolites et 28 stéroïdes dans 1ml de salive. Parmi eux, les concentrations de 8 métabolites et 13 stéroïdes présentaient des variations significatives entre les premiers prélèvements à 140 jours d'âge et les derniers prélèvements à la puberté. En particulier, plusieurs métabolites (formate, malonate, propionate) et stéroïdes (estradiol-17béta et déhydroépiandrostérone) présentaient des variations significatives lors de l’entrée dans la phase de pré-puberté. Ils pourraient être des biomarqueurs de cette phase. Des travaux sont en cours pour vérifier la pertinence de ces biomarqueurs potentiels. Ce travail confirme que des prélèvements salivaires non invasifs pourraient permettre un repérage du stade physiologique des cochettes.

National audience

National audience; Two trials were carried out to compare the farrowing process and piglet characteristics (body weight, survival rate, and diarrhoea) from birth to weaning when sows (168 in total) are fed on an iso-net energy (NE) basis with a gestation (G) or a lactation (L) diet from the arrival in the farrowing unit to the day of farrowing. In both trials, NE and digestible lysine contents were fixed to 9.0 MJ and 5.0 g/kg, respectively, for the G diet and to 9.7 MJ and 8.5 g/kg for the L diet. In trial 2, diet G contained more insoluble fibre and diet L contained more soluble fibre than those of trial 1. When diet G was replaced by diet L, the daily allowance was reduced by 200 g/d (nulliparous sows: 3.0 kg L vs 3.2 kg diet G/d) or 300 g/d (other parities: 3.2 kg L vs 3.5 kg G/d) so that daily supply of NE was similar for both treatments. The iso-NE switch from diet G to L did not significantly impair frequency of faecal excretion before farrowing, sow body temperature after farrowing or frequency of diarrhoea in litters. During trial 2, diet G significantly improved the farrowing process at the beginning of parturition, whereas diet L improved it at the end. A better survival rate was observed for small piglets (i.e., weighing less than 1 kg) with diet L. The statistical power was not high enough to obtain a significant improvement in average birth weight with diet L (1.45 vs 1.41 kg, P = 0.34), but the number of small piglets tended to be smaller with diet L before farrowing. More investigation on the relationship between soluble fibre and the farrowing process or with an earlier supply of diet L would be interesting.; Le déroulement de mise bas (MB) et les caractéristiques des porcelets de la naissance au sevrage sont comparés dans deux essais impliquant 168 truies sont alimentées sur une base iso-énergie nette (EN) avec de l'aliment de gestation (G) ou de lactation (L) de l'entrée en maternité à la MB. Dans les deux essais, l'aliment G contient 9,0 MJ EN et 5,0 g de lysine digestible (LYSd) par kg, contre 9,7 MJ EN et 8,5 g LYSd /kg pour l'aliment L. Dans l’essai 2, l'aliment G contient plus de fibres insolubles et l'aliment L plus de fibres solubles que dans l'essai 1. Lors du remplacement de l'aliment G par de l'aliment L, la ration est réduite de 200 g/j (nullipares : 3,0 kg L vs 3,2 kg G/j) à 300 g/j (autres rangs : 3,2 kg L vs 3,5 kg G/j) afin d'apporter la même quantité d'EN par jour aux truies des deux lots. Le changement iso-EN d'aliment n’impacte ni la fréquence des déjections avant MB, ni la température de la truie après MB ni la fréquence des diarrhées sur la portée. Dans l'essai 2, l'apport d'aliment G améliore le rythme de naissance en début de MB, mais l’aliment L améliore la fin de la MB, ce qui contribue probablement à une meilleure survie des petits porcelets. La puissance expérimentale de l'étude est insuffisante pour démontrer une amélioration significative du poids de naissance avec l'aliment L (1,45 vs 1,41 kg, P = 0,34), néanmoins le nombre de porcelets de moins de 1 kg tend à être plus faible dans ce lot. Il serait intéressant de poursuivre cette étude par des investigations sur la relation entre fibres solubles et MB, ou en démarrant la distribution d'aliment L plus tôt.

Estrus synchronization is important for optimal management of gilt reproduction in farms. Synthetic progestogens are used for this purpose, but there is growing demand for non-hormonal alternatives. Before puberty, gilts exhibit a “waiting period”, related to ovarian development and gonadotrophin secretions, during which external stimulation, such as boar exposure, could induce and synchronize first ovulation. Practical non-invasive tools for identification of this period in farms are lacking. During this period, urinary estrone levels are high, but urine sampling is difficult in group-housed females. Our aim was to search for steroidal biomarkers of this “waiting period” from immature to pubertal gilts through saliva monitoring. Six 144-to 147-day-old Large White gilts were subjected to ultrasound puberty diagnosis 3 times a week until first ovulation. Urine and saliva samples were collected at the same frequency for estrone assay and steroidome analysis respectively. Data were analyzed using the R software (nonparametric permutation test). Urinary estrone concentration significantly increased 2 weeks before puberty (detected at 182–192 days). Steroidome analysis quantified 28 steroids in saliva. Significant variations were detected within 2 weeks before puberty for dehydroepiandrosterone (decrease) and estradiol-17b (increase). These steroids could be biomarkers of the “waiting period”. These results confirm that non-invasive salivary sampling could allow the identification of the physiological status of the gilts and presumably the optimal time for application of the boar effect.

Evaluation of salivary metabolome and steroidome for the identification of biomarkers of the pubertal stage of maturity in gilts. 2. Journées du GdR 3606 Repro

Synchronizing oestrus in gilts is an important tool for pig producers to optimize the management of reproduction. Synthetic progestogens are used routinely in pig farms for this purpose, but there is a need for alternative non-hormonal breeding tools. Before puberty, gilts exhibit a “waiting period”, related to ovarian development and gonadotrophin secretions, during which an external stimulation, such as boar exposure, could induce and synchronize the first ovulation. Our aim was to characterize this “waiting period” and search for biomarkers of this period using non-invasive tools. During this period, an increase of urinary oestrone concentration has been observed, but urinary sampling is difficult in group-housed females. Salivary samples are non-invasive and easier to perform. Thus, the aim of this study was to evaluate steroid concentrations in the saliva of immature to pubertal gilts in order to search for biomarkers of the “waiting period”. Trans-abdominal ultrasonographies were performed over a period of 5 weeks on six 140-day-old Large White gilts until puberty detection. Urinary samples were collected for oestrone assay to detect the “waiting period”. Salivary samples were collected for steroidome analysis using gas chromatography coupled with tandem mass spectrometry to detect potential biomarkers of the “waiting period”. Urinary oestrone concentration increased 2 weeks before puberty. Steroidome analysis allowed the quantification of 28 steroids, 13 of them showing significant differences between weeks. Dehydroepiandrosterone concentrations decreased and estradiol-17 concentrations increased significantly just before the “waiting period”. These steroids could be biomarkers of this period. Present results confirm that non-invasive salivary samples could allow the identification of the physiological status of the gilts and the optimal time for application of the boar effect.

National audience; The addition of antibiotics, either alone or in cocktail mixtures, represents today the only way to control bacterial growth during swine semen production and conservation. In general, raw ejaculates are handed at 30-34 °C while delivering and storage of AI doses occur at temperatures around 16-17 °C. However, the risk of inducing bacterial resistance represents a great challenge to overcome. During this study, we set to develop an antibiotic free semen processing technique that at the same time allows for maintenance of sperm quality and does not affect the fertility performance of swine herds. Ejaculates collected from boars of proven fertility were split in two portions and diluted in two different semen extenders. One portion was diluted in a commercial semen extender supplemented with a classical antibiotic mixture and packed in standard semen bags. The second portion was diluted in a new semen extender with no antibiotic addition and packed in bacteriostatic semen bags. Doses were cooled down up to 4°C after packing and kept in a regigerator until inseminations were performed. Computed assisted semen analysis and flow cytometry analysis were carried for evaluating motility, viability and bacterial charge. Further, sixty gilts (n=60) of the cross breed Large-White x Landrace were selected and aleatory grouped. For heat synchronization, eighteen doses of Regumate (20mg) were given daily to the experimental animals. Only gilts found in heat after the synchronization were included in the study. A total of 30 gilts were inseminated with semen doses supplemented with antibiotics and the other 30 with semen doses without antibiotics. Twenty two days after insemination, pregnancy was checked by transabdominal echography, and pregnant gilts were slaughtered for controlling embryo development and number of corpora lutea present in the ovaries at day 30 post insemination. Neither number of embryos, nor ovulation rates (controlled by the number of corpora lutea formed after ovulation) were affected by the antibiotic free AI doses. These results show that antibiotics are no longer necessary for preservation of boar ejaculates as long as minimal hygienic conditions are kept during semen processing.

National audience

National audience; Effective methods for synchronizing oestrus in gilts are crucial for implementation of batch management and optimum reproductive performances. Altrenogest treatments are used on a routine basis in pig farms, but there is growing demand for alternative non-hormonal breeding tools. Before puberty, gilts exhibit a “waiting period”, related to ovarian development and gonadotrophin secretions, during which urinary oestrone concentration increase. During this “waiting period”, an external stimulation, such as boar exposure, could induce the first ovulation. As non-invasive tools are required to increase knowledge about the “waiting period”, the aim of this work is to search for specific biomarkers of this period in urine. Trans-abdominal ultrasonographies were carried out for 5 weeks in six 140 days old Large White gilts until puberty detection (week -5 to week -1 before puberty). Urinary samples were collected for oestrone assay and metabolome analysis using 1H Nuclear Magnetic Resonance. Gilts were then slaughtered 7 days after puberty detection for puberty confirmation. Urinary oestrone concentration increases from week -2 to the day of puberty detection. Metabolome analysis allows the identification of 78 spectral bins, 8 of them showing significant differences between weeks. Metabolites whose concentration significantly increase or decrease during the “waiting period” (such as Trigonelline, N-acetyl-X…) could be interesting biomarkers of this period. These results confirm that non invasive urinary samples could make it possible to detect optimal time for application of boar effect. Potential urinary biomarkers of this period have been identified. This could contribute to decreasing the number of females mated while they are pre-pubertal.

National audience; Effective methods for synchronizing oestrus in gilts are crucial for implementation of batch management and optimum reproductive performances. Altrenogest treatments are used on a routine basis in pig farms, but there is growing demand for alternative non-hormonal breeding tools. Before puberty, gilts exhibit a “waiting period”, related to ovarian development and gonadotrophin secretions, during which urinary oestrone concentration increase. During this “waiting period”, an external stimulation, such as boar exposure, could induce the first ovulation. As non-invasive tools are required to increase knowledge about the “waiting period”, the aim of this work is to search for specific biomarkers of this period in urine. Trans-abdominal ultrasonographies were carried out for 5 weeks in six 140 days old Large White gilts until puberty detection (week -5 to week -1 before puberty). Urinary samples were collected for oestrone assay and metabolome analysis using 1H Nuclear Magnetic Resonance. Gilts were then slaughtered 7 days after puberty detection for puberty confirmation. Urinary oestrone concentration increases from week -2 to the day of puberty detection. Metabolome analysis allows the identification of 78 spectral bins, 8 of them showing significant differences between weeks. Metabolites whose concentration significantly increase or decrease during the “waiting period” (such as Trigonelline, N-acetyl-X…) could be interesting biomarkers of this period. These results confirm that non invasive urinary samples could make it possible to detect optimal time for application of boar effect. Potential urinary biomarkers of this period have been identified. This could contribute to decreasing the number of females mated while they are pre-pubertal.

Effective methods for synchronizing estrus in gilts are crucial for strict implementation of batch management and optimum reproductive performances. Altrenogest treatments are used on a routine basis in pig farms, but there is growing demand for alternative non‐hormonal breeding tools. Before puberty, gilts exhibit a “waiting” period, related to ovarian development and gonadotrophin secretions, during which external stimulation, such as boar exposure, could induce the first ovulation. As noninvasive tools are required to increase knowledge about the waiting period, the aim of this work is to search for specific biomarkers of this period in saliva. Trans‐abdominal ultrasonography was carried out for 5 weeks in six 140‐day old Large White gilts until puberty detection (week ‐5 to week ‐1 before puberty). We collected saliva samples as well as urinary samples for estrone assay to detect the waiting period. Gilts were then slaughtered 7 days after puberty detection for puberty confirmation. The salivary metabolome was analyzed using 1H Nuclear Magnetic Resonance. Urinary estrone assays are in progress. The concentrations of some saliva metabolites significantly increased (propionate and butyrate for example) or decreased (pyruvate and fumarate for example) between week ‐5 and week ‐1 before puberty. The identification of other metabolites whose salivary concentration significantly varied is in progress. These results suggest that some salivary metabolites could be biomarkers of the pre‐pubertal stage in gilts. Salivary monitoring may help to investigate optimal time for application of boar effect and could contribute to decreasing the number of females mated while they are pre‐pubertal.

Le comportement de truies de types génétiques alternatifs a été évalué à l’aide de 3 tests reproductibles et généralisables. Les résultats obtenus (bonne manifestation de l’œstrus, absence d’agressivité envers l’homme) montrent que ces truies sont utilisables en élevages. Partenaires impliqués : Chambre Régionale d’agriculture des pays de la Loire, Florence Maupertuis, Aude Dubois - Chambre d’agriculture de Maine et Loire, Ferme expérimentale des Trinottières, Denis Olivier - INRA GenESI, Stéphane Ferchaud, Patrick Manceau, Yoann Bailly - INRA Senah, Marie-Christine Meunier-Salaün - IFIP, Sylviane Boulot, Valérie Courboulay[br/] Projets et programmes de recherche dans lequel/lesquels le projet s’intègre : DUROC plein air bio, Région Pays de La Loire - Crédit incitatif INRA Phase, Film d’illustration du comportement maternel de la truie

Dans les élevages porcins français, en moyenne un porcelet né vivant sur sept meurt avant le sevrage. Le poids de naissance et sa variation intra-portée sont deux facteurs déterminants de la survie post-natale des porcelets. Aussi, définir des pratiques d’élevage visant à réduire le nombre de petits porcelets ou l’hétérogénéité des portées à la naissance permettra de concilier des impératifs de compétitivité des élevages et un souci de meilleure acceptabilité sociale de la filière. L’hétérogénéité des portées se manifeste dès la fin du développement embryonnaire et s’amplifie pendant le développement foetal. De ce fait, l’hétérogénéité pourrait être réduite par des stratégies alimentaires appliquées à la truie avant l’insémination en modulant la qualité des ovocytes et des follicules, ou pendant le développement foetal en stimulant les échanges de nutriments entre la mère et les foetus. Notre étude consiste à évaluer l’effet de stratégies alimentaires portant sur deux nutriments spécifiques, le dextrose et la L-arginine, fournis à la truie à deux périodes stratégiques, respectivement avant la fécondation et pendant le dernier tiers de la gestation. Le dextrose stimulerait la sécrétion d’insuline et d’IGF-I, et ainsi la maturation folliculaire et ovocytaire. La L-arginine est un précurseur commun de l’oxyde nitrique (NO), qui stimule l’angiogénèse et la vasodilatation des vaisseaux sanguins, et des polyamines qui régulent les synthèses d’ADN et de protéines.

La mortalité des porcelets avant le sevrage est en partie liée à l’hétérogénéité du poids de naissance intra‐portée. Notre étude évalue l’effet de stratégies alimentaires portant sur le dextrose et la L‐arginine sur l’hétérogénéité de la portée à la naissance. Dans l’essai 1, trois traitements ont été comparés qui consistaient en une supplémentation de 190 g/j de dextrose pendant la semaine précédant l’insémination et de 25,5 g/j de L‐arginine du 77ème jour de gestation jusqu’à la mise bas (lot DEXA, n = 26), une supplémentation de L‐arginine en fin de gestation (lot ARGI, n = 24), ou aucune supplémentation (lot TEM, n = 23). Les traitements n’influencent ni le nombre ni le poids des porcelets nés totaux (NT) ou nés vivants (NV). Le coefficient de variation (CVPV) du poids de naissance intra‐portée est réduit dans les lots ARGI et DEXA comparativement au lot TEM (respectivement sur NT : 21,7, 23,1 et 25,9%, P = 0,06 ; sur NV : 21,0, 22,2 et 25,6%, P = 0,03). Les performances des porcelets pendant la lactation ne diffèrent pas entre traitements.Dans l’essai 2, conduit dans un autre élevage expérimental avec différents modes de logements, seuls les traitements TEM et ARGI ont été comparés. L’effet positif de l'apport de L‐arginine n’a pas été observé (CVPV de 20,7 et 21,8% respectivement pour ARGI, n = 16, et TEM, n = 13). L’impact de la supplémentation en L‐arginine sur l’hétérogénéité des portées à la naissance pourrait dépendre des élevages et de la conduite des truies., Pre‐weaning piglet mortality is partlyattributed to within‐litter variation in piglet birth weight. This study investigated the influence of different feeding strategies on within‐litter variation of piglet birth weight. Maternal diets were supplemented with dextrose and (or) L‐arginine. In trial 1, three treatments were compared: supplementations of dextrose during the week before insemination (190 g/d) and L‐arginine (25.5 g/d) from day 77 of gestation until term (DEXA, n = 26); supplementation of L‐arginine only (ARGI, n = 24); and no supplementation (TEM, n = 23). The treatments did not influence the number or body weight of total born (TB) or born alive (BA) piglets. The coefficient of variation of birth weight (CVBW) was lower in the DEXA and ARGI groups than in the TEM group (for TB: 21.7, 23.1 and 25.9%, P = 0.06; for BA: 21.0, 22.2 and 25.6%, P = 0.03, respectively). Piglet performance during lactation did not differ among groups. In trial 2 that was carried out in another experimental herd with different housing conditions,only TEM and ARGI treatments were compared. The benefit of L‐arginine supplementation during pregnancy on heterogeneity was not observed (CVBW: 20.7 and 21.8% in the ARGI group, n = 16, and the TEM group, n = 13, respectively). The influence of L‐arginine on within‐litter variation in piglet birth weight might depend on herd and (or) sow management.

National audience

National audience; Une étude récente conduite dans un réseau d'élevages, confirme la faible contribution du verrat et de la qualité initiale de la semence aux variations de performances de reproduction. De nombreux facteurs liés à la conduite d'élevage peuvent interférer avec la qualité de la semence livrée.

National audience; Des analyses de la qualité du sperme sont réalisés dans les centres d'insémination artificielle. Si la plupart des examens sont réalisés à l'aide d'un microscope, de nouvelles techniques automatisées se développent.

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