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Dietary habits exert significant selective pressures on anatomical structures in animals, leading to substantial morphological adaptations. Yet, the relationships between the mandible and diet are still unclear, raising issues for paleodietary reconstructions notably. To assess the impact of food hardness and size on morphological structures, we used an experimental baseline using a model based on the domestic pig, an omnivorous mammal with bunodont, thick-enameled dentition, and chewing movements similar to hominids. We hypothesized that the consumption of different types of seeds would result in substantial differences in the morphology of the mandible despite similar overall diets. The experiment was conducted on four groups of juvenile pigs fed with mixed cereal and soy flours. The control group received only flours. We supplemented the four others with either 10 hazelnuts, 30 hazelnuts, 30% barley seeds, or 20% corn kernels per day. We investigated the shape differences between the controlled-fed groups using three-dimensional geometric morphometrics. Our results provide strong evidence that the supplemental consumption of a significant amount of seeds for a short period (95 days) substantially modify the mandibular morphology of pigs. Our analyses suggest that this shape differentiation is due to the size of the seeds, requiring high and repeated bite force, rather than their hardness. These results provide new perspectives for the use of mandibular morphology as a proxy in paleodietary reconstructions complementing dental microwear textures analyses.

International audience

Méthodes alternatives pour la supplémentation en fer des porcelets. Diaporama de la présentation.

International audience; So far, the most common and efficient iron supply to prevent neonatal anemia in piglets has been the injection of iron dextran or gleptoferron. This treatment is problematic because the use of chemically-synthesized allopathic drugs is strictly limited in organic farms. Based on the observation that piglets raised outdoors seldom develop anaemia, we hypothesized that piglets satisfy their needs in iron by ingesting soil from their environment. We compared the efficiency of a 100-mg iron dextran intramuscular injection (Dex, 8 litters, n=98 piglets) at 5 days of age (d5), with daily ad libitum supply of dried soil (Soil, 8 litters, n=101) or dried peat-like river mud (Peat, 8 litters, n=102) from day 5 to weaning on d49. Pigs were raised according to organic pig faming rules. Blood was collected on 3 males and 3 females per litter on d5, 21, 42, 50 and 70. A severe digestive E. coli episode affected piglets during the experiment: litter mortality rate between d5 and d70 did not differ between groups (24%, P>0.1). Body weight was similar (P>0.1) in the three groups on d5 (1.89 ± 0.02 kg), d21 (5.19 ± 0.07kg), d42 (10.0 ± 0.2 kg), d50 (11.8 ± 0.2 kg) and d70 (24.1 ± 0.4 kg). Blood haemoglobin concentration (Hb) was similar in all groups at d5, weaning and d70 (7.8, 10.1 and 10.0 ± 0.1 g/L). However, Hb was greater in Peat and Dex groups (10.4 and 9.9 ± 0.4 g/L) than in the Soil group (7.8 ± 0.4 g/L, P

International audience; Estrus synchronization is necessary for management of gilt reproduction in pig farms. It is usually achieved by using synthetic progestagens, but there is increasing demand for non-hormonal alternative tools with the prospect of sustainability of livestock production. Moreover, in organic farms, synthetic hormones are not allowed. Before reaching puberty, gilts exhibit a “waiting period” during which external stimulations, such as boar exposure, could trigger and synchronize the first ovulation. However, practical non-invasive tools for detection of the “waiting period” in pig farms are lacking. During this period, estrone levels in urine are high, but urine sampling is difficult in group-housed females. Our objective was to identify among steroids potential biomarkers of this “waiting period” through saliva monitoring from immature to pubertal gilts using gas chromatography coupled to tandem mass spectrometry. Starting between 144 and 147 days of age, six Large White gilts were submitted to ultrasound puberty diagnosis 3 times a week until first ovulation. Urine and saliva samples were collected to analyze weekly estrone and steroidome respectively, until puberty. Urinary estrone concentration significantly increased 2 weeks before first ovulation occurring between 182 and 192 days of age. The period with increasing estrone levels was considered as the “waiting period”. Steroidome analysis allowed identifying and quantifying 28 steroids in 500 µl of gilts saliva. Significant decrease of dehydroepiandrosterone and significant increase of 5α-dihydroprogesterone and 17β-estradiol were detected 2 weeks before puberty, suggesting that these steroids could be potential biomarkers of the “waiting period”. These results show that painless sampling of saliva could be a non-invasive welfare-friendly tool for the identification of the physiological hormonal status of the gilts and possibly the optimal time for application of the boar effect, a solution to synchronize puberty without exogenous hormones.

International audience; Male pigs are commonly surgically castrated, without anaesthesia, to avoid a meat quality defect called boar taint, partially due to accumulation of androstenone in fat. Androstenone is a steroid produced by the testes. To decrease boar taint without using castration, a selection against androstenone should be considered. The purpose of this study is to estimate the relationships between androstenone and reproductive traits in boars. In this study we collected 34 traits for 36 Duroc boars, 40 French Landrace boars and 38 Pietrain Axiom NN boars. Characteristics of the semen (number of spermatozoids, mobility, motility, volume, concentration, duration of ejaculation and viability), libido indicators (number of training sessions before the first successful collection and percentage of later refusals), plasma testosterone and oestradiol levels, backfat levels of androstenone, skatole and indole at 180 and 280 day old, the age at 100 kg, the weight of genital tract and indicators of animal behaviour, health and welfare (human-animal relationship test, tears, health and leg scores). We estimated a high Pearson correlation between plasma oestradiol and androstenone in backfat at around 180 days of age (0.57). This confirms that plasma oestradiol can be used as a proxy for androstenone at the standard slaughter age. From Principal Component Analyses, it seems that fat androstenone at 180 days of age is independent from health score, behaviour toward human, libido and semen characteristics. These results suggest that a selection for lower androstenone in fat or plasma oestradiol in pigs at a standard slaughter age would have very-limited impact on libido or semen production capacities of mature boars.

Lactation and gestation are among the physiological events that trigger the most intense changes in body calcium (Ca) fluxes. Along with the composition of the animal 2021 diet, these events are suspected to impact the Ca isotopic composition of Ca body reservoirs but their dynamics are poorly understood. In this study, we monitored a group of domestic sows across a full reproduction cycle. We collected tissues and fluids (blood, urine, milk, colostrum, umbilical blood, adult and piglet bones) at different steps of gestation and lactation, and analyzed their Ca isotopic compositions (i.e. δ44/42Ca) by means of multi-collector inductively coupled plasma mass spectrometry. Among other results, we report the first observations of Ca isotopic fractionation between maternal and umbilical blood (Δ44/42Caumbilical blood-sow blood = −0.18 ± 0.11‰, n = 3). Our data also highlight that gestation and lactation periods are characterized by small diet-bone Ca isotopic offsets (Δ44/42Cabone-diet = −0.28 ± 0.11‰, n = 3), with 44Ca-enriched blood compositions during nursing (Δ44/42Canursing blood-gestation blood = $+ 0.42{\rm{\,\,}}_{ - 0.12}^{ + 0.11}$‰, n = 3). Under the light of an up-to-date mammalian box model, we explored different scenarios of gestation and lactation Ca fluxes experienced by a sow-like animal. These simulations suggest that gestation changes on body δ44/42Ca values may result from the intensification of Ca absorption by the animal, whereas the production of 44Ca-depleted milk is the main driver for the 44Ca enrichment in blood during lactation. In addition, our results also support that bone mineralization could be associated with a more restricted Ca isotopic fractionation than previously envisioned. Together, these results refine the framework of Ca isotope applications, notably regarding the monitoring of human bone balance and the study of species and ecosystems from the present and the past.

International audience; Estrus synchronization is important for optimal management of gilt reproduction in pig farms. Hormonal treatments, such as synthetic progestogens, are used on a routine basis, but there is a growing demand for non-hormonal alternative breeding tools. Before puberty, gilts exhibit a ‘waiting period,’ related to the ovarian development and gonadotrophin secretions, during which external stimulations, 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 oestrone levels are high, but urine sampling is difficult in group-housed females. The aim of this work was to search for specific biomarkers of the ‘waiting period’ in saliva and urine. In total, nine 144- to 147-day-old Large White gilts were subjected to trans-abdominal ultrasonography three times a week for 5 weeks until puberty detection (week –5 to week –1 before puberty). Urine and saliva samples were collected for oestrone assay to detect the ‘waiting period’ and for metabolome analysis using 1H-nuclear magnetic resonance spectroscopy to detect potential biomarkers of the ‘waiting period.’ Gilts were slaughtered 7 days after puberty detection for puberty confirmation. Results were consistent with ultrasonography data for six gilts. Urine and saliva samples from these six gilts were analyzed. Urinary estrone concentration significantly increased 2 weeks before puberty detection. Metabolome analysis of urine samples allowed the identification of 78 spectral bins, among them, 42 low-molecular-weight metabolites were identified. Metabolome analysis of salivary samples allowed the identification of 59 spectral bins, among them, 23 low-molecular-weight metabolites were detected and 17 were identified. No potential biomarker was identified in urinary samples. In saliva, butyrate and 2HOvalerate, 5.79 ppm (putatively uridine), formate, malonate and propionate could be biomarker candidates to ascertain the pre-puberty period in gilt reproduction. These results confirm that non-invasive salivary samples could allow the identification of the physiological status of the gilts and presumably the optimal time for application of the boar effect. This could contribute to synchronize puberty onset and hence to develop non-hormonal breeding tools.

International audience; The thick-enameled, bunodont dentition shared by most early hominins has traditionally been interpreted as reflecting durophagy, especially in the robust genus Paranthropus. However, subsequent works on dental microwear textures (DMT) and biogeochemical compositions have challenged this hypothesis. Some authors argued that their robust morphology might have been driven by the consumption of mechanically challenging resources during periods of food scarcity. An experimental baseline using a model taxon with bunodont, thickenameled cheek teeth, could help better interpret DMT and test hypotheses regarding the consumption of mechanically challenging foods that could be fallback foods. Besides, earlier studies have shown that DMT can track subtle dietary variations in extant taxa. This study aims at testing the hypothesis that the consumption of various seeds has an impact on DMT of bunodont mammals despite similar overall diets. Trials were conducted on four groups of domestic pigs (Sus scrofa) all fed on mixed cereal and soy flours: the control group received only flours (n = 12), and the three others were supplemented with either 20% corn kernels (n = 6), 30% barley seeds (n =5), or 10 hazelnuts in shell per day (n = 6). We studied phases I and II facets on first molars and on fourth deciduous premolars, and applied a subsampling surface strategy to identify discriminative parameters among dietary groups. Principal Component Analyses show that DMT differ between pigs fed on different types of seeds. Our results also demonstrate that combining both crushing and shearing facets into analyses improves dietary discriminations. This study shows that variables that contribute most to dietary discriminations as selected from the subsampling strategy are mainly height parameters. These results thus support the idea that the consumption of seeds has an impact on the relief of surface textures.

International audience; Optimal management of gilt reproduction requires oestrus synchronization. Hormonal treatments are used for this purpose, but there is a growing demand for non-hormonal alternatives, especially in organic farms. The boar effect is an important alternative opportunity to induce and synchronize oestrus without hormones. Before puberty, gilts exhibit a 'waiting period' during which boar exposure could induce and synchronize the first ovulation. We searched for salivary biomarkers of this period of boar effect receptivity to improve detection of the gilts to stimulate with the perspective of enhancing the efficacy of the boar effect. Saliva samples were collected from 30 Large-White×Landrace crossbred gilts between 140 and 175 days of age. Gilts were exposed twice a day to a boar 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 the first introduction of the boar and were considered receptive to the boar effect, 14 were detected in oestrus more than 8 days after first boar contact, and six did not show oestrus and were considered non-receptive. Saliva samples from six receptive and six non-receptive gilts were analyzed for steroidome and for metabolome using gas chromatography coupled to tandem mass spectrometry and 1H nuclear magnetic resonance spectroscopy, respectively. Four saliva samples per gilt were analyzed: 25 days and 11 days before boar introduction, the day of boar introduction, 3 days later for receptive gilts or 7 days later for non-receptive gilts. Twenty-nine steroids and 31 metabolites were detected in gilt saliva. Salivary concentrations of six steroids and three metabolites were significantly different between receptive and non-receptive gilts: progesterone and glycolate 25 days before boar introduction, 3α5β20α- and 3β5α20β-hexahydroprogesterone, dehydroepiandrosterone, androstenediol, succinate, and butyrate 11 days before boar introduction, and 3β5α-tetrahydroprogesterone on the day of boar introduction. Thus, nine potential salivary biomarkers of boar effect receptivity were identified in our experimental conditions. Further studies with higher numbers of gilts and salivary sampling points are necessary to ascertain their reliability.

National audience

International audience; During ejaculation and the deposition in the female genital tract, spermatozoa undergo hypo-osmotic stress and need to withstand it for optimal fertility. Resistance to hypo-osmotic stress may be affected by the interaction of the spermatozoa with seminal fluid components. The hypo-osmotic resistance of epididymal and ejaculated spermatozoa from dogs, rams and boars was assessed by flow cytometric measurement of sperm viability after incubation in NaCl solutions with osmolalities ranging from 0 to 300 mmol/kg. The hypotonic resistance of epididymal spermatozoa was greater than those of ejaculated spermatozoa in all three species. Among species comparison revealed that ejaculated spermatozoa from dogs were much more resistant than those from rams and boars as 80.4 ± 5.3%, 56.7 ± 4.7 and 9.6 ± 3.6% of live spermatozoa were observed following exposure to an osmolality of 90 mmol/kg in dogs, rams and boars respectively. This can be explained by the fact that dog, ram and boar differ markedly in composition of the seminal plasma owing to the presence (ram, boar) or absence (dog) of seminal vesicles. Hypotonic resistance of epididymal and ejaculated dog spermatozoa was similar whereas ram and boar spermatozoa showed a marked drop in resistance after ejaculation. The in vitro incubation of boar epididymal spermatozoa with raw seminal plasma or the seminal plasma protein fraction induced a similar loss of resistance, suggesting that seminal proteins are involved in the lack of resistance to hypotonic stress of boar ejaculated spermatozoa.

The pig is an emerging animal model, complementary to rodents for basic research and for biomedical and agronomical purposes. However despite the progress made on mouse and rat models to produce genuine pluripotent cells, it remains impossible to produce porcine pluripotent cell lines with germline transmission. Reprogramming of pig somatic cells using conventional integrative strategies remains also unsatisfactory. In the present study, we compared the outcome of both integrative and non-integrative reprogramming strategies on pluripotency and chromosome stability during pig somatic cell reprogramming. The porcine cell lines produced with integrative strategies express several pluripotency genes but they do not silence the integrated exogenes and present a high genomic instability upon passaging. In contrast, pig induced pluripotent-like stem cells produced with non-integrative reprogramming system (NI-iPSLCs) exhibit a normal karyotype after more than 12 months in culture and reactivate endogenous pluripotency markers. Despite the persistent expression of exogenous OCT4 and MYC, these cells can differentiate into derivatives expressing markers of the three embryonic germ layers and we propose that these NI-iPSLCs can be used as a model to bring new insights into the molecular factors controlling and maintaining pluripotency in the pig and other non-rodent mammalians.

International audience; Meiotic recombination parameters like crossover (CO) rate or synaptonemal complex (SC) length are known to vary strongly between individuals and between cells from the same individual. The origins of this variability remain elusive, and little is known about the variations that might occur between different samples and/or over time within the same individual. To document this question, pachytene cells from 3 boars of the Large White breed were analyzed twice, at a 1-year interval, using immunocytological techniques. CO rate, SC length, and MLH1 inter-foci distances varied significantly between the 3 individuals. CO rate and SC length differed significantly between the 2 sampling periods for 1 individual. However, no significant differences were observed between the 2 samples for CO distribution and inter-foci distances in the 3 boars studied.

International audience; In organic agricultural systems, swine and poultry must have access to roughage; in the case of rabbits, roughage must constitute 60% of the diet. Allowing access to forage could be a mechanism for reducing feed-related costs and the need to provide protein via complete feed. One issue is that the nutritional values of different forage types are poorly characterised for these monogastric species. However, based on available data, swine and poultry can at least partially exploit forage-based protein (digestibility: about 50% and 75%, respectively), even though they are not herbivorous. For rabbits, which are herbivorous, the nutritional value of forage is high. Different methods of allowing forage access could be used: turning animals out to grass or through feeding. However, several other issues must be explored before clear recommendations can be made to livestock farmers.; En agriculture biologique, les monogastriques doivent avoir accès à des fourrages grossiers (porcs et volailles) ou que ceux-ci représentent 60 % de leur alimentation (lapins). Les fourrages grossiers constituent une ressource locale disponible dans les systèmes d’élevage biologiques, qui présente un potentiel intéressant (bien que les porcs et les volailles ne soient pas herbivores) pour diminuer le coût alimentaire et le recours à des sources de protéines dans l’aliment complet. Leur valeur nutritionnelle est mal connue mais au vu des résultats disponibles, les porcs et les volailles sont en mesure d’en valoriser les protéines en partie (environ 50 % de digestibilité pour des porcs ; 75 % pour des volailles) alors que les apports énergétiques à attendre sont très faibles. Pour les lapins qui sont des herbivores monogastriques, leur valeur nutritionnelle est élevée. Différents modes de valorisation peuvent être envisagés : pâturage ou distribution à l'auge. En fonction des objectifs et du système d’élevage, une conduite de l’aliment complet avec rationnement et/ou appauvrissement de sa teneur en peut permettre, lorsqu’elle bien maîtrisée, permettre de maintenir des performances techniques élevées en diminuant le coût alimentaire. Cependant, de nombreuses pistes sont encore à explorer avant de proposer des recommandations consolidées aux éleveurs de monogastriques désirant valoriser au mieux les fourrages disponibles sur leur exploitation : niveaux de rationnement, formulation de l’aliment appauvrie en protéines, modalités de distribution, optimisation de la gestion du pâturage, choix des espèces végétales pour favoriser la consommation, en constituent quelques-unes.

The aim of the study was to evaluate the consequences of a divergent selection for residual feed intake (RFI) during growth in a temperate environment (TEMP) on sow performance in a tropical environment (TROP). Sows came from a selection experiment conducted at INRA in which 2 lines were selected for larger (RFI(+)) or smaller (RFI(─)) feed intake than predicted from performance. In the first analysis, a subsample of data obtained in TROP conditions (49 lactations) was compared to those obtained in TEMP on their sibs mated with the same boars (54 lactations). In the second analysis, data obtained in the TROP environment (82 lactations) were analyzed for testing the effect of season (warm vs. hot) and line on sow performance. Except for the lactation length, the interaction between line and climatic environment was not significant for the others traits (P > 0.05). The ADFI expressed per kilogram of litter BW gain tended to be higher in the RFI(+) line bred in the TROP environment (P = 0.080), together with piglet BW at weaning, which tended to be lower (P = 0.080). The ADFI was lower in TROP than in TEMP (4.56 vs. 5.86 kg/d; P = 0.003), with negative consequence on litter BW gain and maternal BW loss. The RFI(-) sows tended to eat less feed than RFI(+) sows during lactation (4.55 vs. 5.86 kg/d; P = 0.099). Litter BW at weaning was higher in the RFI(─) line. The RFI(─) sows ate significantly less feed to produce 1 kg of litter than the RFI(+) sows and tended to lose a larger amount of BW during lactation than the RFI(+) sows (2.40 vs. 3.02 kg/kg and -0.66 vs. -0.39 kg/d, respectively, P < 0.10). Whatever the line, ADFI was reduced by about 21% in the hot season (P < 0.05). Litter BW gain was depressed (P < 0.05) in the hot season (1.72 vs. 2.08 kg/d in the warm season; P = 0.023). Lactation maternal BW loss tended to increase in the hot season (1.10 vs. 0.71 kg/d in the warm season; P = 0.016), but back fat loss remained constant (P = 0.295). In the TROP environment, the amount of feed required to produce 1 kg of litter was not influenced by the line in the warm season (2.53 kg/kg on average; P = 0.99), but it tended to be lower in the RFI(─) line when compared to the RFI(+) line in the hot season (2.06 vs. 3.45 kg/kg; P = 0.050). This higher apparent efficiency in RFI(─) sows was mainly related to greater maternal body reserve mobilization (i.e., BW and back fat losses). In conclusion, selection for low RFI during growth in a TEMP environment did not impair sow and litter performance in tropical conditions.

Individuals carrying balanced constitutional reciprocal translocations generally have a normal phenotype, but often present reproductive disorders. The aim of our research was to analyze the meiotic process in an oligoasthenoteratospermic boar carrying an asymmetric reciprocal translocation involving chromosomes 1 and 14. Different multivalent structures (quadrivalent and trivalent plus univalent) were identified during chromosome pairing analysis. Some of these multivalents were characterized by the presence of unpaired autosomal segments with histone γH2AX accumulation sometimes associated with the XY body. Gene expression in spermatocytes was studied by RNA-DNA-FISH and microarray-based testis transcriptome analysis. Our results revealed a decrease in gene expression for chromosomes 1 and 14 and an up-regulated expression of X-chromosome genes for the translocated boar compared with normal individuals. We hypothesized that the observed meiotic arrest and reproductive failure in this boar might be due to silencing of crucial autosomal genes (MSUC) and disturbance of meiotic sex chromosome inactivation (MSCI). Further analysis revealed abnormal meiotic recombination (frequency and distribution) and the production of a high rate of unbalanced spermatozoa.

The pig is an emerging animal model, complementary to rodents for basic research and for biomedical and agronomical purposes. However despite the progress made on mouse and rat models to produce genuine pluripotent cells, it remains impossible to produce porcine pluripotent cell lines with germline transmission. Reprogramming of pig somatic cells using conventional integrative strategies remains also unsatisfactory. In the present study, we compared the outcome of both integrative and non-integrative reprogramming strategies on pluripotency and chromosome stability during pig somatic cell reprogramming. The porcine cell lines produced with integrative strategies express several pluripotency genes but they do not silence the integrated exogenes and present a high genomic instability upon passaging. In contrast, pig induced pluripotent-like stem cells produced with non-integrative reprogramming system (NI-iPSLCs) exhibit a normal karyotype after more than 12 months in culture and reactivate endogenous pluripotency markers. Despite the persistent expression of exogenous OCT4 and MYC, these cells can differentiate into derivatives expressing markers of the three embryonic germ layers and we propose that these NI-iPSLCs can be used as a model to bring new insights into the molecular factors controlling and maintaining pluripotency in the pig and other non-rodent mammalians.

L'axe corticotrope est une composante majeure des régulations métaboliques et des mécanismes biologiques de l'adaptation. L'activité de l'axe corticotrope et sa fonction sont fortement influencées par des facteurs génétiques. Les expériences présentes ont été conçues pour tester l'hypothèse que la sélection génétique pour un axe corticotrope plus actif peut améliorer la robustesse des porcs. Les expériences ont été faites avec des porcs Large White en race pure. Nous avons d'abord confirmé que la réponse du cortisol à l'ACTH est hautement héritable (h2 = 0,68 ± 0,12) dans cette population et peut donc être utilisée pour réaliser une expérience de sélection divergente. Dès la deuxième génération, de grandes différences dans le caractère de sélection ont été obtenues (concentration plasmatique de cortisol post-ACTH : 84,8 vs 127,5 ng/ml dans les lignées basse et haute, respectivement, P < 10-16), mais aussi dans les caractères de reproduction (35% de spermatozoïdes en plus par éjaculat (P = 3.10-4), un taux de mise bas de 11 points de plus (P > 0,10) et 1,5 porcelet vivant de plus par portée (P = 0,06) dans la lignée haute de reproducteurs G1). Les concentrations élevées de cortisol ont eu une influence négative sur la croissance en post-sevrage (418 vs 394 g/jour, P = 0,0013) et en engraissement (799 vs 754 g/jour, P < 0,0001), mais favorable sur la composition de carcasse (TVM : 58,8 vs 60,4%, lignée basse vs lignée haute, P < 0,001). Ces résultats confirment que l’axe corticotrope a des effets contrastés sur les caractères fonctionnels et de production. Ils devront être confirmés dans la 3° génération de sélection en cours et un bilan global sera réalisé avant de pouvoir proposer le test à l’ACTH comme critère de sélection pour obtenir des animaux plus robustes., The adrenocortical axis is a major component of metabolic regulation and biological adaptation processes. Its activity and functions are strongly influenced by genetic factors. The present experiments were designed to address the hypothesis that genetic selection for a more active adrenocortical axis could improve robustness. They were carried out with purebred Large White pigs. We first confirmed that the cortisol response to ACTH is highly heritable (h2 = 0.68 ± 0.12) in this population and can therefore be used for a divergent selection experiment. As early as the second generation of selection, large differences were obtained in the selection trait (post-ACTH plasma cortisol concentration: 84.8 vs 127.5 ng/mL in the low and high lines, respectively, P < 10-16); differences were also obtained in several reproduction traits (35 % more sperm per ejaculate (P = 3.10-4), 11 points higher pregnancy rate (P > 0.10), and 1.5 more piglets born alive per litter (P = 0.06) in the high line). Higher cortisol concentrations had a negative influence on growth rate during both post-weaning (418 vs 394 g/jour, P = 0.0013) and fattening (799 vs 754 g/jour, P < 0.0001) but improved carcass composition (lean%: 58.8 vs 60.4, low vs high line P < 0,001). These results confirm that the adrenocortical axis activity has a contrasted influence on functional and production traits. They have to be confirmed in the third generation for a comprehensive evaluation of the interest of selecting a more active adrenocortical axis to obtain animals that are more robust.

Correct pairing, synapsis and recombination between homologous chromosomes are essential for normal meiosis. All these events are strongly regulated, and our knowledge of the mechanisms involved in this regulation is increasing rapidly. Chromosomal rearrangements are known to disturb these processes. In the present paper, synapsis and recombination (number and distribution of MLH1 foci) were studied in three boars (Sus scrofa domestica) carrying different chromosomal rearrangements. One (T34he) was heterozygote for the t(3;4)(p1.3;q1.5) reciprocal translocation, one (T34ho) was homozygote for that translocation, while the third (T34Inv) was heterozygote for both the translocation and a pericentric inversion inv(4)(p1.4;q2.3). All three boars were normal for synapsis and sperm production. This particular situation allowed us to rigorously study the impact of rearrangements on recombination. Overall, the rearrangements induced only minor modifications of the number of MLH1 foci (per spermatocyte or per chromosome) and of the length of synaptonemal complexes for chromosomes 3 and 4. The distribution of MLH1 foci in T34he was comparable to that of the controls. Conversely, the distributions of MLH1 foci on chromosome 4 were strongly modified in boar T34Inv (lack of crossover in the heterosynaptic region of the quadrivalent, and crossover displaced to the chromosome extremities), and also in boar T34ho (two recombination peaks on the q-arms compared with one of higher magnitude in the controls). Analyses of boars T34he and T34Inv showed that the interference was propagated through the breakpoints. A different result was obtained for boar T34ho, in which the breakpoints (transition between SSC3 and SSC4 chromatin on the bivalents) seemed to alter the transmission of the interference signal. Our results suggest that the number of crossovers and crossover interference could be regulated by partially different mechanisms.

Chantier qualité GA; International audience; Background: Comparison of male versus female meiotic segregation patterns for Robertsonian translocation (RT) carriers with similar genetic background has rarely been reported in mammalian species. Methods: The aim of this study was to compare the segregation patterns determined for related males and females carrying a 13;17 RT in an animal model (Sus scrofa domestica L.), using dual colour fluorescence in situ hybridization on decondensed sperm nuclei and metaphases II of in vitro-matured oocytes. Results: In males, no association between the trivalent and the XY body was observed in any of the 90 pachytene nuclei studied, and the rate of unbalanced spermatozoa ranged between 2.96% and 3.83%. Female meiotic segregation analyses were carried out on 83 metaphase II oocytes. The rate of unbalanced gametes was higher in females than in males (28.91% versus 3.21%, P < 0.001). This difference was due to higher rates of diploid gametes (12.04% versus 0.05%) and unbalanced gametes produced by the adjacent segregation (16.86% versus 3.16%). Conclusions: This study is a new scientific contribution to the comparison of segregation patterns in related males and females carrying an identical chromosomal rearrangement. It allows a better understanding of the meiotic behaviour of RTs. It also clearly illustrates the relevance of swine as an animal model for such meiotic studies.

Male infertility is an increasing health issue in today's society for both human and livestock populations. In livestock, male infertility slows the improvement of animal selection programs and agricultural productivity. There is increasing evidence that epigenetic marks play an important role in the production of good-quality sperm. We therefore screened for specific or common epigenetic signatures of livestock infertility. To do so, we compared DNA methylation level in sperm DNA from fertile and infertile boars. We evaluated first the global level of sperm DNA methylation and found no difference between the two groups of boars. We then selected 42 loci of interest, most of them known to be imprinted in human or mice, and assessed the imprinting status of five of them not previously described in swine tissues: WT1, CNTN3, IMPACT, QPCT, and GRB10. DNA methylation level was then quantified in fertile and infertile boars at these 42 loci. Results from fertile boars indicated that the methylation level of the selected loci is highly conserved between pig, human, and mice, with a few exceptions, including the POU5F1 (OCT4) promoter and RTL1. Comparison between fertile and infertile boars revealed that one imprinted region, the GNAS locus, shows an increase in sperm DNA methylation in three out of eight infertile boars with low semen quality. This increase in DNA methylation is associated with an altered expression of the genes belonging to the GNAS locus, suggesting a new role for GNAS in the proper formation of functional gametes.

Male infertility is an increasing health issue in today's society for both human and livestock populations. In livestock, male infertility slows the improvement of animal selection programs and agricultural productivity. There is increasing evidence that epigenetic marks play an important role in the production of good-quality sperm. We therefore screened for specific or common epigenetic signatures of livestock infertility. To do so, we compared DNA methylation level in sperm DNA from fertile and infertile boars. We evaluated first the global level of sperm DNA methylation and found no difference between the two groups of boars. We then selected 42 loci of interest, most of them known to be imprinted in human or mice, and assessed the imprinting status of five of them not previously described in swine tissues: WT1, CNTN3, IMPACT, QPCT, and GRB10. DNA methylation level was then quantified in fertile and infertile boars at these 42 loci. Results from fertile boars indicated that the methylation level of the selected loci is highly conserved between pig, human, and mice, with a few exceptions, including the POU5F1 (OCT4) promoter and RTL1. Comparison between fertile and infertile boars revealed that one imprinted region, the GNAS locus, shows an increase in sperm DNA methylation in three out of eight infertile boars with low semen quality. This increase in DNA methylation is associated with an altered expression of the genes belonging to the GNAS locus, suggesting a new role for GNAS in the proper formation of functional gametes.

International audience; For the first time in the domestic pig, meiotic recombination along the 18 porcine autosomes was directly studied by immunolocalization of MLH1 protein. In total, 7,848 synaptonemal complexes from 436 spermatocytes were analyzed, and 13,969 recombination sites were mapped. Individual chromosomes for 113 of the 436 cells (representing 2,034 synaptonemal complexes) were identified by immunostaining and fluorescence in situ hybridization (FISH). The average total length of autosomal synaptonemal complexes per cell was 190.3 µm, with 32.0 recombination sites (crossovers), on average, per cell. The number of crossovers and the lengths of the autosomal synaptonemal complexes showed significant intra- (i.e. between cells) and inter-individual variations. The distributions of recombination sites within each chromosomal category were similar: crossovers in metacentric and submetacentric chromosomes were concentrated in the telomeric regions of the p- and q-arms, whereas two hotspots were located near the centromere and in the telomeric region of acrocentrics. Lack of MLH1 foci was mainly observed in the smaller chromosomes, particularly chromosome 18 (SSC18) and the sex chromosomes. All autosomes displayed positive interference, with a large variability between the chromosomes.

Chantier qualité GA Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Access; International audience; Inversions are well-known structural chromosomal rearrangements in humans and pigs. Such rearrangements generally have no effect on the carrier's phenotype. However, the presence of an inversion may impair spermatogenesis and lead to the production of recombinant gametes, responsible for early miscarriages, stillbirth, or congenital abnormalities. This is the first report on meiotic segregation and pairing behavior of the inv(4)(p1.4;q2.3) pericentric inversion in pigs. Despite the very large size of the inverted fragment (76% of the chromosome), SpermFISH results showed that only 4.08% of the gametes produced by male heterozygotes were unbalanced. This low proportion could be explained by theparticular behavior of normal and inverted SSC4 chromosomes during the initial stages of meiosis. Indeed, immunohistochemistry analyses revealed that heterosynapsis occurred in 92% of the cells, whereas synaptic adjustment was detected in a few spermatocytes only. Unexpectedly, the proportion of unbalanced gametes produced by female heterozygotes, estimated by FISH on metaphase II oocytes, was also very low (3.69%) and comparable to that in males. According to previous results for male and female meiotic processes, different proportions of recombinant gametes in the two genders would have been expected. Complementary studies should be carried out to further document the meiotic behavior of inversions in pigs.

Licence

In organic farming, weaning piglets remains a critical period, although later than in the conventional system. The use of hormones being forbidden in organic system, heat synchronization is absent, which leads to spread of birth associated with heterogeneous ages, weight and health status of the piglets. The differences can be accentuated by a poorly adapted solid diet before and after weaning. The aim of the study was to understand the difference involved in the physiological mechanisms in piglet adaptation strategies to propose adapted feeding strategies. The studied population of fifty piglets, from four genetic lines, comes from 5 sows (Landrace x Duroc) of the INRA-Genesi unit and a boar (Pietrain x Large White). Five batches, of ten pigs per sow, were constituted by weight range: four “large” piglets, two "medium" and four "small". They had access to a second-age feed from ten days and to roughage, high protein, after weaning (Wrapped alfalfa). Animals weights were recorded on days (d) 1-10-21-28 42-48-55-62. Blood samples were collected at d 42-48-55-62 for inflammatory indicators and oxidative stress measurements around weaning. Behavioural observations in farrowing room at d 15-20-30-40 and at post-weaning at d 43, were carried out to establish weaning adaptation profiles. The results showed that the small piglets at d 42 were on the posterior teats and that there was no clear indication if the piglets ate more solid feed in the farrowing room compared to the larger piglets. At post-weaning, it was shown that the small piglets were on average more present in the area of feeding interest than the larger ones. The smaller piglets also had a higher haptoglobin rate than the large and medium piglets. Finally, there was no weight compensation from the smaller piglets compared to the mediums and larger piglets. The average weight significantly differs between all three categories at d 42 and d70.

DEUG

Diplôme : BTSA

Diplôme : BTSA