Search

The composition and structure of fleece variation observedin mammals is a consequence of a strong selective pressure for fiber production after domestication. In sheep, fleece variation discriminates ancestral species carrying a long and hairy fleece from modern domestic sheep (Ovis aries) owning a short and woolly fleece.Here, we report that the “woolly” allele results from the insertion of an antisenseEIF2S2retrogene (calledasEIF2S2)intothe3 0 UTR of theIRF2BP2 gene leading to an abnormal IRF2BP2 transcript. We provide evidence that this chimeric IRF2BP2/asEIF2S2 messenger 1) targets the genuine sense EIF2S2 RNA and 2) creates a long endogenous double-stranded RNA which alters the expression of both EIF2S2 and IRF2BP2 mRNA. This represents a unique example of a phenotype arising via a RNA-RNA hybrid, itself generated through a retroposition mechanism. Our results bring new insights on the sheep population history thanks to the identification of the molecular origin of an evolutionary phenotypic variation. Instituto de Genética Fil: Demars, Julie. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Cano, Ema Margarita. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; Argentina Fil: Drouilhet, Laurence. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Plisson-Petit, Florence. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Bardou, Philippe. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Fabre, Stéphane. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Servin, Bertrand. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Sarry, Julien. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Woloszyn, Florent. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Mulsant, Philippe. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Foulquier, Didier. Institut National de la Recherche Agronomique; Francia Fil: Carriere, Fabien. Institut National de la Recherche Agronomique; Francia Fil: Aletru, Mathias. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Rodde, Nathalie. Institut National de la Recherche Agronomique; Francia Fil: Cauet, Stéphane. Institut National de la Recherche Agronomique; Francia Fil: Bouchez, Olivier. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Pirson, Maarten. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Tosser-Klopp, Gwenola. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia Fil: Allain, Daniel. Université de Toulouse. GenPhySE; Francia. Institut National de la Recherche Agronomique; Francia

Increasing behavioural autonomy of animals ensures their adaptation to various environments and contributesto the sustainability of livestock production. More particularly, maternal behaviour is vital for the offspringsurvival. Breed differences in maternal behaviour are well known but genetic variation within breed has beenpoorly investigated. The aim of the study was to estimate in sheep genetic parameters for maternal reactivityand search QTL associated with the related behavioural traits. Ewes (n=851) reared outside were individuallyphenotyped just after lambing in two behavioural tests based on the reactivity to separation from their lambsand/or to a human. Ewes were tested for one or two lambing. In the first test performed outdoor 2 hours afterlambing, the ewe’s reactivity was assessed by measuring flight distance from lambs, time to restore contactwith lambs and facility to follow transport of lambs. In the second test performed indoor 24 h after lambing,the ewe’s reactivity was assessed by measuring vocalizations, locomotion and proximity to lambs with orwithout human presence. Lamb mortality was recorded until weaning. Heritability estimates were moderate(h2=0.11 to 0.23±0.05) for flight distance from lambs, time to restore contact with lambs and facility to followthe transport of lambs. Genetic correlations between these traits ranged from 0.78 (±0.21) to 0.95 (±0.06). Forthe second test, heritability estimates ranged from 0.11 (±0.05) for proximity to 0.50 (±0.05) for vocalizations.Genetic correlations ranged from 0.13 (±0.06) to 0.44 (±0.07). Lamb mortality was significantly lower in ewesshowing a higher maternal reactivity. A genome wide association study of maternal reactivity is currentlycarried on in ewes genotyped using the Illumina ovineSNP50 beadchip. The moderate to high heritabilities andpotential SNPs polymorphisms for the behavioural traits of ewes may offer opportunities in genetic selectionfor improving maternal behaviour and reducing lamb mortality.

International audience; In sheep, the bond between the dam and her lambs is established during the first hours of a lamb's life. Genetic variability for behavioural reactivity of ewes assessed in an arena test performed 24 hr after lambing has already been reported. However, there is no evidence that this reactivity represents the ewe's maternal reactivity at lambing in outdoor conditions. The objective of this study was to investigate whether or not the behavioural reactivity of ewes in the arena test is genetically related to their maternal reactivity measured at lambing. A total of 935 Romane ewes were studied. The maternal reactivity of ewes at the outdoor lambing site was recorded in response to a human approach and to the handling of the lambs. Their behavioural reactivity was also recorded 24 hr post-lambing in the arena test that involved a separation from the litter and a human presence. Flight distance, aggressive reaction, time to restore contact with the litter, maternal behaviour scores and vocalizations recorded at the lambing site were heritable (0.12-0.34). All of these behaviours were genetically correlated with the behavioural reactivity in the arena test. The highest genetic correlations (from 0.60 to 0.90) were found amongst maternal behavioural scores, flight distance and high-pitched bleats. In conclusion, behavioural reactivity in the arena test can be used to assess early maternal reactivity in standardized conditions. Phenotyping of ewes' behavioural reactivity with a simplified arena test can be performed for genetic improvement in maternal behaviour in sheep.

The objective of our study was to investigate with bio-technical and economic simulations, whether recognising the diversity of rangeland resources and re-organising reproductive and feeding management in consequence could improve the performance of extensive meat sheep systems. We used data from an experimental farm (INRA La Fage, Larzac plateau, southern France) to build a virtual case study. The farm comprises a flock of 330 ewes with high potential productivity (Romane breed, prolificacy > 240%), reared outdoors in a harsh environment: 280 ha of rangelands of which 18 ha have been long fertilized. We applied changes in flock management (1st lambing at 2 years, lambing date matching grass growth) and grazing management (function of each paddock, adapted paddock size, timing and intensity of utilisation over the year). Based on model predictions, the new system is more sustainable, with a higher net income (+40%) and a lower consumption of non renewable energy (-29%). These changes are explained mainly by a higher proportion of grazed forage (0.73 compared to 0.56 of total dry matter consumption, i.e. +30%), especially on rangelands (+50%), which reduces the energy and money needed to supply the flock with conserved forage and concentrate. The simulation results need to be validated with field data. A better knowledge of rangeland-based system is required to improve model calibration., Notre objectif était de déterminer avec des simulations biotechniques et économiques si prendre en compte la diversité des parcours et réorganiser la conduite de la reproduction et du pâturage en conséquence pouvait améliorer les performances des systèmes d’élevage ovins viande extensifs. Nous nous sommes appuyés sur les données d’une ferme expérimentale (INRA La Fage, Plateau du Larzac) pour construire une ferme virtuelle : 330 brebis avec un potentiel de production élevé (race Romane, prolificité > 240%) conduites en plein air intégral dans un milieu difficile (280 ha de parcours dont 18 ha fertilisés de longue date). Nous avons modifié la conduite du troupeau (1ère mise-bas à 2 ans, mise-bas calée sur la pousse de l’herbe) et la conduite du pâturage (fonctions aux parcs, taille des parcs, périodes et intensités d’utilisation adaptées). Les prévisions des modèles suggèrent que le nouveau système est plus durable, avec un revenu net plus élevé (+40%) et une consommation d’énergie non renouvelable plus faible (-29%). Ces changements sont dus principalement à l’augmentation des fourrages pâturés (0,73 contre 0,56 de la consommation totale de matière sèche, i.e. +30%), en particulier sur les parcours (+50%), ce qui réduit l’énergie et l’argent nécessaires pour fournir au troupeau des fourrages conservés et des concentrés. Les résultats devront être validés avec des observations de terrain. Une meilleure connaissance des systèmes d’élevages à composante pastorale permettrait d’améliorer le calibrage des modèles.

Chantier qualité GA; International audience; The present study aimed to evaluate an experimental approach to individually assess social reactivity among sheep. INRA401 male lambs (n = 163) were reared together outdoors as part of a larger flock. Fifteen days after weaning the animals were individually exposed to an arena test of 2 phases (1-social attraction, 2-social isolation) during which proximity toward conspecifics and vocal and locomotor reactivity were measured. One day after the test their inter-individual distances were measured when grazing over a 2-h period in order to estimate their sociability on pasture. This was made using scan sampling recording the identity of the nearest neighbour for each individual, which led to the establishment of a sociability index. Overall, we found that high-pitched bleats recorded during the attraction phase (r = 0.22) and the isolation phase (r = 0.23) of the arena test as well as the locomo-tor activity measured during the isolation phase (r = 0.27) were positively correlated with the sociability index. Furthermore, the behaviour of lambs during the isolation phase of the arena test (i.e. vocal and locomotor agitation) appeared to be a significant predictor explaining 13% of the variance of the sociability on pasture. The behavioural reactivity measured through the arena test thus reflects at least to some extent the sociability of sheep. Those results are very encouraging as they suggest that the sociability of lambs could indeed be evaluated through a short experimental test, which is less time consuming than field ethological observations.

The objective of our study was to investigate with bio-technical and economical simulations, if recognising the diversity of rangeland resources and re-organising reproductive and feeding management in consequence could improve the performance of extensive meat sheep systems. We used data from an experimental farm (INRA La Fage, Larzac plateau, southern France) to build a virtual case study. The farm comprises a flock of 330 ewes with high potential productivity (Romane breed, prolificacy > 240%), reared outdoors in a harsh environment: 280 ha of rangelands of which 18 ha have been long fertilized. We applied changes in flock management (1st lambing at 2 years, lambing date matching grass growth) and grazing management (function to each paddock, adapted paddock size, timing and intensity of utlisation over the year). Based on model predictions, the new system is more sustainable, with a higher net income (+40%) and a lower consumption of non renewable energy (-29%). These changes are explained mainly by a higher proportion of grazed forage (0.73 compared to 0.56 of total dry matter consumption, i.e. +30%), especially on rangelands (+ 50%), which reduces the energy and money needed to supply the flock with conserved forage and concentrate. The simulation results need to be validated with field data. A better knowledge of rangeland-based system is required to improve model calibration.; Notre objectif était de déterminer avec des simulations bio-techniques et économiques si prendre en compte la diversité des parcours et ré-organiser la conduite de la reproduction et du pâturage en conséquence pouvait améliorer les performances des systèmes d’élevage ovins viande extensifs. Nous nous sommes appuyés sur les données d’une ferme expérimentale (INRA La Fage, Plateau du Larzac) pour construire une ferme virtuelle : 330 brebis avec un potentiel de production élevé (race Romane, prolificité > 240%) conduites en plein air intégral dans un milieu difficile (280 ha de parcours dont 18 ha fertilisés de longue date). Nous avons modifié la conduite du troupeau (1ère mise-bas à 2 ans, mise-bas calée sur la pousse de l’herbe) et la conduite du pâturage (fonctions aux parcs, taille des parcs, périodes et intensités d’utilisation adaptées). Les prévisions des modèles suggèrent que le nouveau système est plus durable, avec un revenu net plus élevé (+40%) et une consommation d’énergie non renouvelable plus faible (-29%). Ces changements sont dus principalement à l’augmentation des fourrages pâturés (0.73 contre 0.56 de la consommation totale de matière sèche, i.e. +30%), en particulier sur les parcours (+50%), ce qui réduit l’énergie et l’argent nécessaires pour fournir au troupeau des fourrages conservés et des concentrés. Les résultats devront être validés avec des observations de terrain. Une meilleure connaissance des systèmes d’élevages à composante pastorale permettrait d’améliorer le calibrage des modèles.

International audience; The milk somatic cell score (SCS) is an indirect indicator of mastitis, currently used as a selection criterion of dairy ruminants that leads to decreased intra-mammary infection prevalence. In the present study, gene expression profiles after Staphylococcus stimulations were determined in three cell types of mastitis resistant and susceptible ewes. The comparisons of the lists of the differentially-expressed genes allowed identification of commonly-regulated genes among cell types. These results lead to identify a subset of genes involved in pathogen-related receptor signaling. These genes may play an important role in recognition of pathogens and may improve resistance to intramammary infections.

Among the adaptive capacities of animals, the management of energetic body reserves (BR) through the BR mobilization and accretion processes (BR dynamics, BRD) has become an increasingly valuable attribute for livestock sustainability, allowing animals to cope with more variable environments. BRD has previously been reported to be heritable in ruminants. In the present study, we conducted genome-wide studies (GWAS) in sheep to determine genetic variants associated with BRD. BR levels and BR changes over time were obtained through body condition score measurements at eight physiological stages throughout each productive cycle in Romane ewes (n=1034) and were used as phenotypes for GWAS. After quality controls and imputation, 48,513 single nucleotide polymorphisms (SNP) were included in the GWAS. Among the QTLs identified, a major QTL associated with BR levels during pregnancy and lactation was identified on chromosome 1. In this region, several significant SNPs mapped to the leptin receptor gene (LEPR), among which one SNP mapped to the coding sequence. The point mutation induces the p.P1019S substitution in the cytoplasmic domain, close to tyrosine phosphorylation sites. The frequency of the SNP associated with increased BR levels was 32%, and the LEPR genotype explained up to 5% of the variance of the trait. These results provide strong evidence for involvement of LEPR in the regulation of BRD in sheep and highlight it as a major candidate for improving adaptive capacities.

International audience; The season of births in domestic herds determines the availability of animal production, the organization of agropastoral tasks and herds mobility on the annual scale. It can bemanipulated by the herder to a certain extent and it may have been so early in the history of domestication. Birth season can be investigated through the reconstruction of the seasonal cycle record in teeth, using sequential analysis of stable oxygen isotope ratios in enamel. The season of birth is then determined by comparison with modern references, i.e. oxygen isotope sequences measured in the teeth from animals of knownbirth season. Such works have been conducted in particular in sheep. For those, previous modern references have mostly included winter and early spring births, the season when most births occur under temperate latitudes in Europe. In order to complete the existing framework, we have built a new reference set focusing on autumn births, occurring currently in the western Mediterranean area. This new set is composed of 27 teeth(including second and third molars) from Lacaune and Merinos ewes raised in southern France. We will explain how the set was constituted, present the data for autumn births, connect it to previous data for winter and early spring births on different sheep breeds,and discuss intra- and inter-breeds variability.

International audience; Breeding for resilience requires a better understanding of intra-flock variability and the related mechanisms responsible for robustness traits. Among such traits, the animals’ ability to cope with feed fluctuations by mobilizing or restoring body reserves (BR) is a key mechanism in ruminants. The objective of this work was to characterize individual variability in BR dynamics in productive Romane ewes reared in extensive conditions. The BR dynamics profiles were characterized by combining individual longitudinal measurements of BW and body condition scores (BCS) over several production cycles. Historical data, including up to 2628 records per trait distributed in 1146 ewes, underwent cluster analysis. Two to four trajectories were observed for BW depending on the cycle, while three trajectories were found for BCS, whatever the cycle. Most trajectories suggested that BR dynamics were similar but the level of BR may differ between ewes. Nevertheless, some trajectories suggested that both BR dynamics and levels were different for a proportion of ewes. Clustering on BW and BCS profiles adjusted for individual level trends, resulted in differences only in the level of BW or BCS, rather than differences in trajectories. Thus, the overall shape of trajectories was not changed considering or not the individual level trend across cycles. In addition to individual variability, the ewe’s age at first lambing and litter size contributed to the distribution of the ewes between the trajectories. Regarding the entire productive life, three trajectories were observed for BW and BCS changes over three productive cycles. Increase in BW at each cycle suggested that ewes kept growing up until 3 to 4 years old in our conditions. Similar alternation of BCS gains and losses across cycles suggested BR dynamics might be repeatable. Many individual trajectories remained the same throughout a ewe’s life, whatever the age at first lambing, parity or litter size. Our results demonstrate the relevance of using BW and BCS changes for characterizing the diversity of BR mobilization–accretion profiles in sheep in a long timespan perspective.

International audience

International audience

International audience

International audience

In livestock, improving maternal reactivity towards the litter is an important issue in breeding strategies to promote production and animal welfare. As of yet, no studies have investigated the within-breed genetic variation of maternal reactivity in sheep. The objective of this study was to estimate the genetic parameters of maternal reac-tivity traits. A total of 1,095 primiparous and 1,441 multiparous Romane ewes were phenotyped 24hr postlambing using a behavioural test (arena test, AT) over a 10-year experimental period. The test consisted of three successive phases evaluating the ewe's attraction to her litter, reactivity to separation from her litter, and reactivity to a conflict between attraction to her litter and avoidance of a motionless human. The ewes were reared exclusively on rangelands (South of France) and lambed outdoors in the spring. High-pitched bleating and low-pitched bleating in the AT were mostly highly heritable (0.39‒0.46). Heritabilities were moderate for proximity to the litter in the presence of a human (0.27) and low for locomotion and vigilance in the AT (0.09‒0.15). The measurements of a given behaviour in the three phases of the AT were highly genetically correlated. Few genetic correlations were found between the different behavioural traits in the AT, the highest correlations being between high-pitched bleating and low-pitched bleating (−0.43 to −0.77). In conclusion, our find-ings demonstrate moderate-to-high heritability for maternal reactivity traits. These traits could be included in genetic selection schemes to enhance maternal attachment provided there is no unfavourable link with other production traits.

International audience; Monitoring bodyweight (BW) is a critical practice used for management purposes (e.g. assessing weight gain, body condition or establishing slaughtering schedules). Measuring BW indoors is relatively easy although time and labor consuming. However, recording BW outdoors may become difficult. The aim of this project was to trial an automated small ruminant weighing prototype using the remote weighing concept of walk-over-weighing (WoW), combined with radio-frequency identification and designed to be light, resistant, transportable and autonomous in energy. The BW is collected as the animal crosses freely over the WoW platform, strategically placed in an obligatory path combined with a small yard containing water and mineral salts as incentives. We studied the system's efficacy in a series of experiments under a range of sheep farming situations (i.e. indoor and outdoor). Time required for achieving individual voluntary passages, the number of daily visits and the pro- portion of biologically plausible BW records were analysed. The Lin’s concordance correlation coefficient (CCC) was used to establish the agreement between WoW records and the gold standard BW measurements (static weighing scale). Our results showed the feasibility of recording BW with free and voluntary passage of sheep with controlled sheepflow over the platform while preventing congestion. After 2–3 weeks of adaptation, 100% of animals crossed daily. Sheep misbehaviour (e.g. speed of passage) can result in spurious values and ccounted for many of the larger weight discrepancies. Once outliers were removed, the prediction accuracy of the system and the CCC ranged between 0.89 and 0.98, showing a substantial agreement between the two methods. Using this standalone WoW system, it was possible to record daily individual BW, which may contribute to save labor and time while providing timely information to improve productivity and animal welfare under varying farming conditions.

BACKGROUND: The identification of loci associated with resistance to mastitis or of the causative mutations may be helpful in breeding programs for dairy sheep as it is for cattle worldwide. Seven genomic regions that control milk somatic cell counts, an indirect indicator of udder infection, have already been identified in sheep (Spanish Churra, French Lacaune and Italian Sardinian-Lacaune backcross populations). In this study, we used a 960 custom-designed ovine single nucleotide polymorphism (SNP) chip in Lacaune and Manech Tête Rousse dairy sheep to validate these seven genomic regions associated with mastitis.RESULTS: The most significant SNP (rs868996547) on Ovis aries chromosome (OAR) 3 was a previously described mutation in the suppressor of cytokine signalling 2 (SOCS2) gene. An antagonist effect of this causal candidate between health and growth in Lacaune sheep was confirmed. Effects of the mutation on the infectious status of the udder, i.e. increases in milk somatic cell counts and bacteria shedding, were also identified. This SNP was not present in the data available on Manech Tête Rousse. Three other regions associated with mastitis were also confirmed on OAR16 (Manech Tête Rousse), 19 (Lacaune) and 2 (both breeds). For the OAR2 region, we validated previously detected SNPs in several other breeds (Sarda, Churra, and Chios). For significant SNPs in the four mastitis regions, the effect varied from 0.24 to 0.67 phenotypic standard deviation of the traits. Two of the mastitis quantitative trait loci (QTL) regions (OAR2 and 16) that we validated here were also associated in opposite ways with milk production traits in both populations.CONCLUSIONS: These results indicate, at least in part, a genomic basis for the trade-off between milk production and mastitis resistance. Four of the seven mastitis QTL regions that were previously identified in independent populations, were confirmed in this study, which demonstrates partial sharing of mastitis-related genetic mechanisms between different distant dairy sheep populations.

International audience; Feed is the largest cost in animal production, therefore improving feed efficiency (FE) is one of the main priorities when redesigning farming systems. The objective of this work was to evaluate the effects of a divergent genetic selection for FE in Romane rams [i.e. efficient (RFI-) or inefficient (RFI+)] on the feed intake and nutrient digestibility of their daughters (ewes), reared in different conditions. Different to their sires, which were fed high concentrate-diets, the ewes were fed ad libitum total mixed ration (TMR) composed of silage (65%), hay (25%) and barley (10%). A series of in vivo digestibility trials were conducted using Romane ewes (n =20; 10 RFI- and 10 RFI+) during their 2 first production cycles. The BW, metabolic BW (MBW), body condition score (BCS), DM intake (DMI) and nutrient intake and digestibility were individually monitored. All parameters were significantly affected (P < 0.05) by the production cycle. The BW, MBW, BCS as well as the feed intake and nutrient digestibility were higher in the cycle 2 compared to cycle 1. The exception was the CP digestibility, which was higher in younger ewes (cycle 1). The BW and MBW was, as expected, higher in older ewes thus increasing the feed intake capacity in cycle 2 compared with cycle 1. Slight differences in TMR nutritive composition between the years of the study were also probably responsible of differences in CP digestibility. The RFI+ ewes showed a better BCS than RFI- ewes (3.0 vs. 2.7; P < 0.0001). In the conditions used in this study, we could not demonstrate any differences in intake and digestive efficiency between the two ewe FE lines, probably because the selected rams were tested with one diet (concentrate-based diet) whereas their daughters (ewes) with another (forage-based diet). Further research is warranted to evaluate RFI testing in animals fed a more fibrous diet closer to that of ewes under range conditions whereas also assessing responses to multiple-generation divergent selection on RFI.

International audience; In general, dairy sheep are fed in large groups that receive the same diet based on the average group milk yield (MY), which is increased by approximately 15% and 25% to cover the energy and protein requirements respectively of part of the high-producing ewes, according to the French INRA system recommendations. Despite this, some of the highest producing ewes are still underfed, especially in terms of energy. This experiment was designed to measure the effect of increasing the amount of energy supplement on milk yield, milk composition and forage intake. Three groups of 16 multiparous Lacaune dairy ewes (DIM mean +/- SD: 40 +/- 1.5) producing 3.4 +/- 0.29 L/d, were balanced in terms of MY, milk composition, body weight (BW: 74.7 +/- 8.43 kg) and body condition score (BCS: 2.7 +/- 0.26). During three periods of three weeks (P1, P2, P3), groups were fed a basal diet based on a mixture of herbage silages and good quality hay (173 g CP/kg DM) offered ad libitum. A protein concentrate was offered at a constant level (0.34 +/- 0.034 kg DM/d/ewe) to cover initial protein requirements. Barley grain was offered at three average levels (kg DM/d/ewe): medium (M, 0.478), high (H, 0.667) or very high (vH, 0.883). The three groups (MMH, MHH, MvHH) received the corresponding amount of barley in the three successive periods: in P1, 0.485 for the three groups, in P2, 0.470 for MMH, 0.672 for MHH and 0.883 for MvHH, and in P3, 0.661 for the three groups. Forage and concentrate dry matter intake were measured each week over five days; milk yield and composition (total fat, protein and urea content) were measured once a week; and BW and BCS were measured every two weeks. Modifying the amount of concentrate (P2, P3) gave no significant (P0.05) MY, but slightly increased (P

International audience; In ruminants, body reserves (BR) are mobilized in situations of negative energy balance, including physiological stages with high metabolic challenges. In contrast, BR accretion occurs when nutrient requirements decrease. This dynamic is partly controlled by metabolic patterns, whereas its genetic determinism is still unknown, at least in sheep. The objective of this preliminary study was to estimate genetic parameters for a few key metabolites and hormones involved in sheep BR dynamic. The BR changes over time were monitored over three years on 318 productive Romane ewes reared exclusively in an extensive rangeland. Plasma non-esterified fatty acids (NEFA), beta-hydroxybutyrate (β-OHB) and triiodothyronine (T3) levels were quantified 2 weeks before and 3 weeks after lambing and 2 weeks before mating. Effects of physiological stage, litter size and a parity-year factor were tested to identify main sources of variation. Genetic parameters were estimated using animal mixed model considering independently measurements at each physiological stage. The least square means for NEFA, β-OHB and T3 were significantly (P

International audience; Including behavioural traits in genetic selection could be an advantageous strategy for improving the autonomy of animal to extensive farming systems in an agroecological perspective. More particularly, farm animals are social and gregarious, and relational behaviours are essential for ensuring social cohesion, social facilitation, offspring survival and docility. Breed differences and genetic variation within breed have been reported in sheep for social behaviour and found to be heritable, suggesting such behaviour could be selected. The aim of the present study was to investigate in sheep the efficiency of an early selection for social attractiveness or tolerance to the human. For 7 years, four divergent lines were produced according to the reactivity of lambs to social separation or towards a human. Each year, in average 300 female and male lambs from 250 dams were individually exposed just after weaning to two behavioural tests. The arena test aims at assessing the motivation of the lambs towards conspecifics and the corridor test aims at assessing the reactivity of the lambs to an approaching shepherd. Several behaviours were measured and individual estimated breeding values (EBV) were calculated for selected behaviours for each lamb using an animal mixed model. Extreme animals were chosen according to their high or low EBV either for the frequency of their vocalisations for social reactivity (high vs low frequency), or for the flight distance towards human (short vs long distance). After two generations of selection, the divergent selection led to highly significant line differences for social reactivity or reactivity towards the human. Differences between high and low lines reached 1.8 and 1.0 genetic standard deviation for social reactivity and reactivity towards a human, respectively. Such divergent selections affected significantly locomotor and vigilance behaviours and proximity to flock-mates or the human depending on the lines. Present results confirm that early selection for behavioural traits is feasible. The expected effects on performances and facility to handle flocks will be investigated to assess relevance of such selection for contributing to improve sustainability of livestock.

International audience; Since a few years, breeders are looking to select more robust animals in order to improve adaptation to more challenging environments. One expression of such robustness is a suitable cyclic alternation of accretion and mobilization of body reserves (BR) i.e. BR dynamics. In a previous study, we characterized several BR trajectories based on body condition score (BCS) and body weight (BW) measurements regularly recorded according to a physiological stages schedule. In addition, in a previous multi-traits approach of BR changes over time we found that BR accretion and mobilization were heritable traits and genetically linked. The objectives of the present study were therefore: (1) to evaluate the link between BR trajectories and ewes rearing performances and; (2) to estimate the genetic correlations between BR changes and ewes rearing performances. By using records from 1,146 productive Romane ewes, their rearing performances were estimated by analysing key parameters like the total weight of the litter at lambing and at weaning, and the average daily gain (ADG) of the lamb during their first, second and third month of life. The effects of the BR trajectories of the dam were also tested. Genetic correlations were estimated between the ewes’ BR changes through time and their rearing performances, by conducting animal mixed model analyses. Overall, ewes presenting a stronger decrease in their trajectories during the BR mobilization period, showed superior rearing performances. Negative favourable correlations were found between BR mobilization and the total litter weight at lambing (-0.42±0.15) and between BR mobilization and ADG of lambs during the first and second month of suckling (-0.29±0.14). Positive favourable correlations were found between BR accretion and litter weight at birth (0.42±0.15) and between BR accretion and the lamb ADG during the first month of life (0.37±0.15). Present results suggest that BR dynamics could be considered in genetic selection programs to improve animals’ resilience while enhancing ewes’ performances when facing external challenges.

The main objective of this work was to study the relationships between body reserve (BR) dynamics and rearing performance (PERF) traits in ewes from a Romane meat sheep flock managed extensively on "Causse" rangelands in the south of France. Flock records were used to generate datasets covering 14 lambing years (YR). The dataset included 1,146 ewes with 2 ages of first lambing (AGE), 3 parities (PAR) and 4 litter sizes (LS). Repeated measurements of the BW and BCS were used as indicators of BR. The ewe PERF traits recorded were indirect measurements for maternal abilities and included: prolificacy, litter weight and lamb BW at lambing and weaning, ADG at 1, 2 and 3 months after lambing and litter survival from lambing to weaning. The effects of different BW and BCS trajectories (e.g., changes in BW and BCS across the production cycle), previously been characterized in the same animals, on PERF traits were investigated. Such trajectories reflected different profiles at the intraflock level in the dynamics of BR mobilization-accretion cycles. Genetic relationships between BR and PERF traits were assessed. All the fixed variables considered (i.e., YR, AGE, PAR, LS and SEX ratio of the litter) have significant effects on the PERF traits. Similarly, BW trajectories had an effect on the PERF traits across the three PARs studied, particularly during the first cycle (PAR 1). The BCS trajectories only affected prolificacy, lamb BW at birth and litter survival. Most of the PERF traits considered here showed moderate heritabilities (0.17 to 0.23) except for prolificacy, the lamb growth rate during the third month and litter survival which showed very low heritabilities. With exception of litter survival and prolificacy, ewe PERF traits were genetically, strongly and positively correlated to BW whatever the physiological stage. A few weak genetic correlations were found between BCS and PERF traits. As illustrated by BW and BCS changes over time, favorable genetic correlations were found, even if few and moderate, between BR accretion or mobilization and PERF traits, particularly for prolificacy and litter weight at birth. In conclusion, our results show significant relationships between BR dynamics and PERF traits in ewes, which could be considered in future sheep selection programs aiming to improve robustness.

International audience

National audience

International audience; 1. Understanding how functional traits, which are key for plant functioning, relate to demographic parameters of populations is central to tackle pending issues in plant ecology such as the forecast of the fate of populations and communities in a changing world, the quantification of community assembly processes or the improvement of species distribution models. We addressed this question in the case of species from a Mediterranean rangeland of southern France. 2. Changes in species abundance in response to management intensification (fertilization and increased grazing pressure) were followed over a 28-year period. Probabilities of presence, and elasticities of the changes in the probability of space occupancy to colonization and survival, which are analogues of demographic parameters, were calculated for 53 species from the time series of abundance data using a space occupancy model. Nine quantitative traits pertaining to resource use, plant morphology, regeneration and phenology were measured on these species and related to demographic parameters. 3. The long-term dynamics of species in response to management intensification was associated with major changes in functional traits and strategies. Changes in the probability of occurrence—analogous to population growth rate—were correlated with traits describing the fast-slow continuum of leaf functioning. The elasticity of population growth rate to colonization was significantly related to reproductive plant height and seed mass, and to a lower extent, to leaf carbon isotopic ratio. 4. Synthesis. The functional response of species to management intensification corresponds to a shift along the second axis of a recently identified global spectrum of plant form and function, which maps, to some extent, onto the fast-slow continuum of life-history strategies. By contrast, the elasticity of colonization relates to the global spectrum axis capturing the size of organs. Seed mass contributes to this axis and is assumed to relate to one of the important traits structuring the reproductive strategy axis of life histories as well, namely net reproductive rate. While this mapping between functional and life-history traits is appealing, further tests in contrasting types of communities are required to assess its degree of generality.

International audience; Breeding for resilience requires a better understanding of intra-flock variability and the related mechanisms responsible for robustness traits. Among such traits, the animals’ ability to cope with feed fluctuations by mobilizing or restoring body reserves (BR) is a key mechanism in ruminants. The objective of this work was to characterize individual variability in BR dynamics in productive Romane ewes reared in extensive conditions. The BR dynamics profiles were characterized by combining individual longitudinal measurements of BW and BCS over several production cycles. Historical data, including up to 2,628 records per trait distributed in 1,146 ewes, underwent cluster analysis. Two to 4 trajectories were observed for BW depending on the cycle, while 3 trajectories were always found for BCS, whatever the cycle. Most trajectories suggested that BR dynamics were similar but that the level of BR differed between ewes. Nevertheless, some trajectories suggested that both BR dynamics and levels were different for a proportion of ewes. The distribution of the ewes between the trajectories was explained by the ewe’s age, litter size, and individual variability. Many individual trajectories remained the same throughout a ewe’s life, whatever the age, parity, or litter size. Our results demonstrate the relevance of using BW and BCS for characterizing the diversity of BR mobilization-accretion profiles in sheep in a long timespan perspective. This is probably the first report of proven intra-flock variability in the adaptive capacities of grazing sheep. Nevertheless, further research efforts are needed to complete the characterization of BR dynamics by including other physiological (e.g., a set of plasma metabolites and hormones) and zootechnical parameters to obtain new insights into the complex mechanisms determining individual robustness.

International audience; Improving milking ability is a major issue for consideration in dairy species. Milk flow is not yet recorded in dairy sheep flocks and so far recorded only in the INRA experimental sheep flock of La Fage. The objective of our study was thus to estimate heritability estimates for milk flow traits and genetic correlations with milk production and with udder health traits in dairy Lacaune sheep. Genetic parameters were estimated by multivariate REML with an animal model on first - lactation field data of 377,945 Lacaune ewes for milk production and somatic cell count traits, on additional experimental data of 1,641 ewes for milk flow and 518 ewes for intra-mammary bacterial infection. Heritability estimates were high for annual milk flow traits (ranging from 0.36 to 0.64) and moderate for subclinical intra-mammary infections (0.18). A low to moderate (from -0.13 to +0.53) genetic correlations were found between milk yield and milk flow traits and indicated that the current selection in Lacaune sheep based on yield is associated to an increase of both parameters, milk flow and milking time. Lactation somatic cell score was positively correlated with subclinical intra-mammary infections (+0.72) and unfavourably associated with milk yield (+0.12). These results reinforce the interest of including LSCS in the breeding objectives of dairy sheep in order to balance the negative effect of selecting for increased production on udder health. The genetic correlation of intra-mammary infections with latency time was unfavourable and moderate (-0.33). The hypothesis was that ewes with high milk flow rate may have a lower sphincter tone facilitating pathogen entry.

International audience; Maternal behaviour is vital for the offspring survival. In animal production, improvement of maternal behaviour is becoming increasingly important in order to improve lamb survival particularly in extensive systems. Breed differences in maternal behaviour and genetic variation within breed have previously been described in several farm species. However, any study has investigated genetic loci underlying such behaviour in sheep. The aim of the study was to identify QTL associated with maternal behaviours in sheep using ovineSNP50 beadchip. Ewes reared outside were genotyped (n=470) and individually phenotyped after lambing for maternal behaviours in two standardized behavioural tests. QTL detection was performed by linkage, association and joint linkage and association analyses. Six main QTL regions identified on chromosomes 4, 13, 16, 21, and 23 showed significant associations with vocalizations. Four main QTL regions identified on chromosomes 4, 9, and 23 showed significant associations with maternal behaviour scores. Some of these QTLs contain interesting candidate genes, previously described to be associated with behaviours, which may explain a substantial amount of the genetic variation in maternal behaviours in sheep.

International audience; During the transition from late gestation to early lactation ruminants experience a negative energy balance (NEB), which is considered to increase susceptibility to mammary infections. Our previous study in 2 divergent lines of sheep selected for high and low somatic cell score (SCS) suggested an association between the response to NEB and genetic susceptibility to mastitis. Forty-eight early-lactation primiparous dairy ewes from the 2 SCS genetic lines were allocated to 2 homogeneous subgroups-an NEB group, which was energy restricted and received 60% of the energy requirements for 15 d, and a control-fed group-to obtain 4 balanced groups of 12 ewes: high-SCS positive energy balance, low-SCS positive energy balance, high-SCS NEB, and low-SCS NEB. High-SCS ewes showed greater weight loss and increased plasmatic concentrations of beta-hydroxybutyrate and nonesterified fatty acids than low-SCS ewes when confronted with an induced NEB. The aim of this study was to further characterize this interaction by combining transcriptomic and phenotypic data with a generalized partial least squares discriminant analysis using mixOmics package framework. A preliminary analysis using 3 blocks of phenotypes (fatty acids, weight and production, blood metabolites) revealed a high correlation between fat-to-protein ratio, beta-hydroxybutyrate, and nonesterified fatty acids concentrations with milk long-chain fatty acid yields. These phenotypes allowed good discrimination of the energy-restricted high-SCS ewes and confirmed a high level of adipose tissue mobilization in this group. A second analysis, which included RNA-seq data, revealed high correlations between the long-chain fatty acid yields in milk and PDK4, CPT1A, SLC25A20, KLF10, and KLF11 expression, highlighting the relationship between mobilization of body reserves and enhanced fatty acids utilization for energy production in blood cells. Finally, analysis of milk composition measured in 1,025 ewes from the 2 genetic lines over 10 yr confirmed significant higher fat-to-protein ratio in high-SCS ewes in early lactation. Altogether, our results strongly confirmed a genetic link between susceptibility to mastitis and metabolic adaptation to energy shortage. Improving genetic resistance to mastitis using SCS should be accompanied by a favorable effect on the response to metabolic stress, especially in highly stressful early lactation. Moreover, this study suggests that the fat-to-protein ratio could be used as a low-cost tool for monitoring energy balance and ketosis during this critical phase of lactation.

The aim of this study was to investigate the pleiotropic effects of a Socs2 gene point mutation associated to lower resistance to mastitis, an inflammation of the mammary gland, mostly due to bacterial infection by Staphylococci in dairy sheep. GWAS were performed on SCC (Somatic Cell Count), bacterial infection, animal size and milk production using a 960 custom-designed ovine SNP chip and a data set of 504 Lacaune dairy ewes. The resultsconfirmed the strong effect of this mutation on the inflammatory response (p-value of LSCS_L1 = 3.03e-07 and p-value of abscess = 2.83e-03), a slighter effect on animal size (pvalue of W_ DAY_250 = 3.71e-04) and also showed for the first time an effect of this mutation on intramammary infections (p-value of STAPH_L1 = 6.80e-04). In contrast, no effect on milk production could be confirmed (p-value of MILK_L1 = 2.01e-01), suggesting an indirect role of SOCS-2 protein on milk production. Then pleiotropy tests (CLIP test) proved pleiotropic effects of the mutation on SCC, bacterial infection, size and more indirectly on milk production.

National audience; Les systèmes d’informations (SI) de phénotypage des animaux, appelés Sicpa suivi du nom de l’espèce (Bovins, Caprins et Ovins, Porcins, Lapins, Volailles, Poissons et Equins), sont des outils informatiques d’acquisition de données et de gestion des élevages. Ces projets sont développés dans le cadre du Cati Sicpa, par des informaticiens des Départements GA (Génétique Animale) et Phase (Physiologie Animale et Systèmes d’Élevage). Ils permettent de mettre à disposition des agents d’élevage des outils assurant la fiabilisation des saisies, de centraliser les informations dans des bases de données structurées et sécurisées, et de restituer simplement aux scientifiques des jeux de données aussi propres que possible. Ces SI ont été mis en place progressivement depuis le début des années 1990 et sont en perpétuelle évolution, répondant aux nouveaux besoins demandés, d’une part par les scientifiques pilotant des expéri‑ mentations, et d’autre part par les nouvelles méthodes de collectes des informations de terrain (adaptation des logiciels aux chantiers, automatismes...). Ces SI sont, depuis quelques années, des actifs stratégiques du Département GA. En 2017, ils sont utilisés dans 36 élevages (et 13 élevages en phase de transition) dans les huit espèces.

International audience; The microbiota of herbivorous animals plays a central role in the nutrition of its host, directly affecting his health and his ability to produce. Very few publications reported results concerning the impact of host genetics on the composition of ruminal microbiota. Thus, we proposed to study the genetic determinism of bacterial relative abundances of sheep rumen microbiota. 369 dairy Lacaune ewes raised indoor at the INRA Experimental Farm of La Fage, had a sampling of their rumen fluid done. These ewes were adult animals, fed with a 93% hay-silage based diet and belonged to 4 different lines (lines divergently selected on somatic cells count or on milk persistency). Ruminal metagenome were sequenced using 16s rRNA gene with Illumina Miseq technology. Bioinformatics analysis of the microbiota sequences were implemented with FROGS pipeline to obtain relative abundances of bacteria and R Phyloseq package to estimate biodiversity indices. Heritability estimates of the square root of relative abundances were computed in single trait using the VCE 6.0 software. FROGS pipeline allowed clustering the 4,944,307 informative sequences into 2,135 OTUs, which represented 247 bacteria taxas (140 genera, 50 families, 31 orders, 17 classes and 9 phyla). Significant differences between lines were observed: 4 bacteria generas have abundancies differences according to CCS lines (Olsenella, Prevotella 1, Prevotellaceaea Ga6a1, Syntrophococcus with always higher values for CCS+) and 4 others according to PERS lines (Coprococcus 1, Olsenella, Succonivibrionaceae U2, Syntrophococcus). At the genera scale, heritabilities estimates ranged from 0.00 to 0.49 with a standard error of 0.11 on average: 22% of genera had heritabilities higher than 0.1, which is lower than Estellé et al. on Large White (50% genera with h2>0.1). The most heritable genera (h2>0.25) were Ruminococcaceae UCG002, Lachnospira, Atopobium and Oscillospira which also were taxa with low abundances.

International audience; Improving animal’s robustness will contribute to overcome current and future economic, environmental and societal challenges in the small ruminant sector in Europe. The ability of ewes to mobilize and to restore body reserves (BR) is a key mechanism to cope with quantitative and qualitative variations in feed resources. The aims of this work were to characterize the different patterns of BR changes throughout productive cycles and to analyze the genetic variability of such changes in French meat sheep. Temporal changes in BR dynamics were investigated using Body Condition Score (BCS) measured frequently throughout repeated entire productive cycles in ewes reared exclusively outdoors in harsh conditions. The analysis showed three different clusters for BCS variations whatever the productive cycle. Major clusters were mainly characterized by BR accretion during dry-off period and early pregnancy and BR mobilization during mid-pregnancy and suckling. Clusters differed in the BCS level and profiles of variation. The heritability values were low to medium for BCS variations (h2=0.06 to 0.15). High negative genetic correlations for BCS variations between dry-off period and pregnancy and/or suckling indicated BR mobilization and accretion were two genetically correlated processes. These results showed that BR variations could be used in selection to increase robustness.

National audience

The overall sustainability and innovative capacity of the sheep and goat sector in Europe have to be improved to cope with current and future economic, environmental and societal challenges. Innovations in genetic resource management and breeding for sheep and goat populations will be explored in the iSAGE European project (WP5) in order to help the industry to cope with such future challenges. In France, genetic evaluation for small ruminants is performed in a large variability and poorly characterized environments. In this regard, we will consider multi-generation data from existing French breeding programs and experimental field studies. Effects of herd for traits under genetic selection will be investigated in commercial farms in order to better characterize the production environment, particularly using meteorological data but also feeding, breeding system and economic criteria. Such characterization will enable to follow-up trends in animal performances according to weather changes. This work could also contribute to characterize farm typologies to which a set of sustainability indicators will be tested. Then, contrasted environments will be identified and genotype by environment interactions studies will be carried out aiming to improve genetic selection efficiency in a variety of environments. In addition to existing data, we will explore new phenotypes considered as key functional traits for robustness and for which stakeholders are particularly interested. These new phenotypes will be also explored in combination with feed efficiency in experimental facilities under contrasted environments or under feed shortage challenges. Genetic and genomic studies will be performed for new phenotypes used to assess individual robustness. The total merit indices will be revisited from the technical and economic point of view in order to evaluate economic weights of each trait in the "breeding goal", for diversified production systems.; En France, l’évaluation génétique des petits ruminants estime simultanément la valeur génétique des reproducteurs ainsi que les effets d’environnement dont le plus important est l’effet troupeau. Cette évaluation est réalisée dans des environnements variés et mal caractérisés faisant l’hypothèse d’absence d’interaction GxE. Pour tester cette hypothèse et disséquer les composantes des effets troupeaux, les environnements de production seront caractérisés à partir des données collectées en fermes (disponibles dans les systèmes nationaux d’information génétique ou collectées ponctuellement) décrivant les systèmes d’élevages et des données météorologiques. La discrimination des types d’environnements de production établis par la typologie des élevages permettra d’analyser les interactions GxE pour différentes races ovines et caprines en France.Par ailleurs, l’adaptation des petits ruminants à ces environnements variés et changeants implique entre autre leur efficacité d’utilisation des ressources et leur capacité biologique à mobiliser et reconstituer leurs réserves énergétiques sous forme de lipides. Des travaux expérimentaux seront conduits pour étudier les mécanismes biologiques et le déterminisme génétique de la dynamique des réserves corporelles en lien avec l’efficacité alimentaire. Cette approche permettra d’identifier de nouveaux phénotypes pour l’amélioration génétique de la robustesse des petits ruminants.

International audience; The overall sustainability and innovative capacity of the sheep and goat sector in Europe have tobe improved to cope with current and future economic, environmental and societal challenges. Innovations ingenetic resource management and breeding for sheep and goat populations will be explored in the iSAGE Eu-ropean project (WP5) in order to help the industry to cope with such future challenges. In France, genetic eval-uation for small ruminants is performed in a large variability and poorly characterized environments. In this re-gard, we will consider multi-generation data from existing French breeding programs and experimental fieldstudies. Effects of herd for traits under genetic selection will be investigated in commercial farms in order tobetter characterize the production environment, particularly using meteorological data but also feeding, breed-ing system and economic criteria. Such characterization will enable to follow-up trends in animal performancesaccording to weather changes. This work could also contribute to characterize farm typologies to which a setof sustainability indicators will be tested. Then, contrasted environments will be identified and genotype by en-vironment interactions studies will be carried out aiming to improve genetic selection efficiency in a variety ofenvironments. In addition to existing data, we will explore new phenotypes considered as key functional traitsfor robustness and for which stakeholders are particularly interested. These new phenotypes will be also explored in combination with feed efficiency in experimental facilities under contrasted environments or under feedshortage challenges. Genetic and genomic studies will be performed for new phenotypes used to assess in-dividual robustness. The total merit indices will be revisited from the technical and economic point of view inorder to evaluate economic weights of each trait in the “breeding goal”, for diversified production systems.; En France, l’évaluation génétique des petits ruminants estime simultanément la valeur génétique des reproducteurs ainsi que les effets d’environnement dont le plus important est l’effet troupeau. Cette évaluation est réalisée dans des environnements variés et mal caractérisés faisant l’hypothèse d’absence d’interaction GxE. Pour tester cette hypothèse et disséquer les composantes des effets troupeaux, les environnements de production seront caractérisés à partir des données collectées en fermes (disponibles dans les systèmes nationaux d’information génétique ou collectées ponctuellement) décrivant les systèmes d’élevages et des données météorologiques. La discrimination des types d’environnements de production établis par la typologie des élevages permettra d’analyser les interactions GxE pour différentes races ovines et caprines en France. Par ailleurs, l’adaptation des petits ruminants à ces environnements variés et changeants implique entre autre leur efficacité d’utilisation des ressources et leur capacité biologique à mobiliser et reconstituer leurs réserves énergétiques sous forme de lipides. Des travaux expérimentaux seront conduits pour étudier les mécanismes biologiques et le déterminisme génétique de la dynamique des réserves corporelles en lien avec l’efficacité alimentaire. Cette approche permettra d’identifier de nouveaux phénotypes pour l’amélioration génétique de la robustesse des petits ruminants.

International audience

Negative Energy Balance (NEB) is considered to increase susceptibility to mastitis. The objective of this study was to improve our understanding of the underlying mechanisms by comparing transcriptomic profiles following NEB and a concomitant mammary inflammation. Accordingly, we performed RNA-seq analysis of blood cells in energy-restricted ewes and control-diet ewes at four different time points before and after intra mammary challenge with phlogogenic ligands. Blood leucocytes responded to NEB by shutting down lipid-generating processes, including cholesterol and fatty acid synthesis, probably under transcriptional control of SREBF 1. Furthermore, fatty acid oxidation was activated and glucose oxidation and transport inhibited in response to energy restriction. Among the differentially expressed genes (DEGs) in response to energy restriction, 64 genes were also differential in response to the inflammatory challenge. Opposite response included the activation of cholesterol and fatty acid synthesis during the inflammatory challenge. Moreover, activation of glucose oxidation and transport coupled with the increase of plasma glucose concentration in response to the inflammatory stimuli suggested a preferential utilization of glucose as the energy source during this stress. Leucocyte metabolism therefore undergoes strong metabolic changes during an inflammatory challenge, which could be in competition with those induced by energy restriction.

National audience

Chez les ruminants, le déficit énergétique est associé à une sensibilité plus marquée aux mammites. Un certain degré de déficit énergétique est fréquent en période post-partum en raison de l’augmentation insuffisante de l’ingestion par rapport aux besoins en énergie pour la lactation. Cependant, les mécanismes liant fonction immunitaire, réponse inflammatoire et bilan énergétique demeurent mal connus. L’objectif de cette étude était donc de décrire les conséquences du déficit énergétique d’une part et la réponse à une épreuve inflammatoire d’autre part, ainsi que leur effet combiné, sur l’expression génique des leucocytes sanguins chez des brebis primipares en début de lactation. Pour cela, 24 brebis laitières ont été réparties en deux groupes homogènes : un groupe dont le bilan énergétique était négatif (BEN) avec une couverture de 60 % des besoins énergétiques à la suite d’une restriction des apports pendant 15 jours, et un groupe témoin dont les besoins énergétiques étaient couverts à 100 % et le bilan énergétique positif (BEP). Après 11 jours de ces régimes alimentaires, une solution de phlogogènes (Pam3CSK4 et MDP) a été injectée dans une hémi-mamelle saine afin d’induire une réponse inflammatoire chez toutes les brebis. L’analyse du transcriptome a été réalisée par la technique RNA-seq sur les leucocytes sanguins des brebis à quatre dates : 4 jours avant le début de la restriction énergétique, puis après 11 jours de régime alimentaire différencié, à 0, 8 et 24 h après l ‘induction de l’inflammation mammaire. L’analyse RNA-seq a révélé une inhibition des fonctions d’oxydation du glucose, et de synthèse du mévalonate, du cholestérol et des acides gras, et une activation de l’oxydation des acides gras en réponse au BEN dans les leucocytes sanguins. Elle a également révélé une activation marquée de la transcription en réponse précoce à l’épreuve inflammatoire (8 h après l’injection), notamment des voies de signalisation immunitaires comme B Cell Receptor Signaling ou Leukocyte Extravasation Signaling. Alors qu’aucune interaction entre le régime et la réponse à l’épreuve inflammatoire n’a pu être établie, certaines fonctions biologiques, en particulier le métabolisme lipidique et les voies de production énergétique, étaient modifiées de façon contraire par les deux stress. En effet, l’épreuve inflammatoire a entrainé une activation de l’oxydation du glucose et une inhibition de l’oxydation des acides gras, indiquant une utilisati

International audience; Dairy ruminants experiencing a severe postpartum negative energy balance (NEB) are considered to be more susceptible to mastitis. Although the genetic variability of mastitis resistance is well established, the biological basis of the link between energy metabolism and resistance is mostly unknown. The aim of this study was to characterize the effect of NEB on metabolism and immune response according to the genetic background for mastitis resistance or susceptibility. Forty-eight ewes from high and low somatic cell score (SCS) genetic lines were allocated to 2 homogeneous subgroups 2 wk after lambing: one group (NEB) received an energy-restricted diet to cover 60% of their energy requirements, and the other group received a control (positive energy balance: PEB) diet. Both diets met the protein requirements. After 10 d on either the NEB or PEB diet, all ewes were injected with a Pam3CSK4/MDP solution in one half-udder to induce an inflammatory response. The ewes were monitored for milk production, somatic cell count (SCC), body weight (BW), body condition score (BCS), and blood metabolites. Differential milk cell counts were determined by flow cytometry. Plasma concentrations of glucose, insulin, nonesterified fatty acids (NEFA), p-hydroxybutyrate (BHB), and triiodothyronine were determined. Energy restriction resulted in an increased fat:protein ratio in milk and decreased milk yield, BW, and BCS. The NEB ewes had significantly higher NEFA and BHB and lower plasma glucose concentrations than PEB ewes, reflecting a mobilization of body reserves and ketone body synthesis. High-SCS ewes had a higher SCS than low-SCS throughout the experiment, except after the inflammatory challenge, which resulted in similar SCS in all 4 groups. A noteworthy interaction between genetic background and diet was evidenced on metabolic parameters and BW. Indeed, high-SCS ewes subjected to NEB showed greater decrease in BW and increased NEFA and BHB concentrations compared with low-SCS ewes. Thus, NEB in early lactation led to extensive mobilization of body reserves and intense ketone body synthesis in mastitis-susceptible sheep. These results reinforce the hypothesis of a genetic association between mastitis susceptibility and energy metabolism and open the way to further studies on the biological basis for this association.

Polyethylene glycol (PEG) measured with NIRS is known to be a valuable faecal marker when used in indoor experiments. In order to verify whether it can be used at pasture, an experiment was conducted with two trials. In trial 1, six Romane breed adult dry ewes placed in metabolism cages were fed daily with natural, freshly cut rangeland from a fertilised or unfertilised paddock for 6 weeks. Three ewes did not receive PEG and the three others were dosed with 10 g of PEG in solution form once daily until the end of the experiment to measure in vivo dry matter digestibility and PEG recovery rate for each forage quality. At the same time (trial 2), 15 ewe lambs and 14 lactating adult ewes suckling one or two lambs were allowed to graze together on the same herbage as that cut for indoor ewes. All animals were initially equipped with faecal bags emptied twice daily for collecting total faeces, and eight ewe lambs and seven adults were dosed once daily with 10 g of PEG. Faecal grab samples were collected for 4 to 5 days for each forage quality grazed. Indoor trial 1 showed that PEG had no effect on dry matter intake (DMI) or on digestibility. PEG recovery rates measured on fertilised (77.7%) and unfertilised (82.1%) forage were not different ( P>0.05). PEG recovery rates measured at pasture did not differ( P>0.05) between pasture quality and animal type with an average value of 68.9%. Faecal output measured with bags or estimated with PEG and calculated DMI were not different ( P>0.05) when PEG recovery rate measured at pasture was used. Conversely, using indoor PEG recovery values, significantly ( P

Une série d’expérimentations a été conduite pour mesurer l’impact de la monotraite à l’échelle de la lactation de brebis laitières de race Lacaune. La production de lait et sa composition, la physiologie et la morphologie de la mamelle, l’ingestion et le métabolisme énergétique ont été mesurés tout au long de la période de traite, du sevrage au tarissement. L’impact de la monotraite a été modélisé à l’échelle de l’exploitation et du bassin de production. La perte de lait a été de 14% chez les multipares comme les primipares. Selon la ration offerte, le taux butyreux a diminué ou a eu tendance à augmenter, alors que le taux protéique n’a pas été modifié ou a augmenté en lien avec une augmentation des protéines solubles. Les quantités ingérées n’étaient pas différentes entre brebis en traite biquotidienne et monotraite, ce qui a entraîné un bilan énergétique positif supérieur pour ces dernières. Cela s’est traduit par des taux d’acides gras non estérifiés rapidement plus bas et de leptine supérieurs. La mamelle a été perturbée dans les premiers jours de monotraite, mais a rapidement retrouvé son intégrité du fait d’une bonne plasticité sans aucune conséquence sur sa santé. Au niveau de l’exploitation, la monotraite entraîne une perte de revenu qui peut être compensée en tout ou partie par un passage en monotraite à un stade plus tardif ou un allongement de la période de traite. Des travaux complémentaires conduits à l’échelle de l’exploitation permettraient de mieux préciser les répercussions de cette pratique à ce niveau et à celui du bassin de production., Several experiments were conducted for evaluating the effects of once daily milking (ODM) in Lacaune dairy ewes throughout the milking period. Milk production and composition, udder health, daily feed intake and energy metabolism were individually monitored. The effects of adopting ODM at the farm and the production region levels were also modelled. Individual milk yield was 14% lower either in adult or primiparous ewes. Milk fat and protein contents were lower and higher, respectively, when ewes were fed ad libitum; however, these parameters were almost not modified when diets were adjusted to the actual milk yield. Dry matter intake was not affected by ODM, which led to a marked positive energy balance in ODM ewes. The last was well illustrated by the metabolic profile of the ewes, showing lower body reserves mobilization in ODM ewes. The udder morphology and functioning was only disturbed during the first week of ODM, but it was rapidly recovered without associated further health constraints. At the farm level, adopting the ODM regime showed a decrease in the global farm incomes, possibly to be recovered by starting ODM in the mid-lactation or prolonging the milking period length. Further researches will be required for characterizing in a deeper way the related effects of applying ODM under different feeding and management situations at the flock, farm and regional production scales.

L’un des facteurs limitants identifiés dans les années 1950 était le potentiel laitier insuffisant des races de brebis traites en France, qui a initié la collaboration entre profession et recherche qui perdure depuis. Après une phase initiale où les deux stratégies génétiques possibles, croisement ou race pure, ont été explorées, la profession a fait le choix dans les années 1970 de la sélection de chaque race locale dans son terroir de production avec son fromage d'appellation d’Origine Protégée. La réussite de la sélection des cinq races locales concernées est le fruit d’une démarche raisonnée et optimisée dans l’espace (gestion pyramidale) et dans le temps (la quantité de lait, puis les aptitudes fromagères du lait, puis les caractères fonctionnels de la sphère mammaire), et de la mise en œuvre d’objectifs de sélection cumulatifs à l’échelle de chacune des populations concernées. Cette démarche est validée par des va-et-vient permanents entre élevages privés et expérimentaux, ou des expérimentations dans les élevages privés : elle a permis de proposer des solutions inédites comme le contrôle laitier qualitatif ponctuel pour les taux butyreux et protéiques, puis pour les comptages de cellules somatiques, tout en permettant de comprendre l’originalité de milieux de sélection induits par le pilotage global au troupeau, susceptible de favoriser des réponses génétiques indirectes durables (capacité d’ingestion, vitesse de traite et aptitude à la mono-traite des brebis) bien exploitées par les éleveurs. Cette démarche balisée n’interdit pas de sortir du cadre quand il s’agit de répondre à un objectif stratégique et imprévu, comme la résistance à la tremblante dans les années 1990. La diversification pour chacune des cinq races locales de nouveaux objectifs de sélection (aptitude à la mono-traite quotidienne, longévité fonctionnelle, persistance laitière, résistance aux strongles gastro-intestinaux) est susceptible d’intervenir avec le démarrage depuis 2015 de la sélection génomique des brebis laitières françaises., One of the limiting factors identified in the 1950’s was low milk yield level of the French dairy ewes, which initiated the collaboration between breeder organizations and researchers that has been developed. Initially, the two possible genetic strategies, crossbreeding or purebred selection, were investigated. Finally the breeders chose in the 1970’s the selection of each local French dairy sheep breed in its specific area of production related to its PDO cheese. The success of the selection of the five involved local breeds is the result of a rationalized and optimized approach, in space (pyramidal management of the population), and in time (progressiveness of the breeding goals from milk yield only to global merit giving the same weights to milk traits and udder functional traits). This approach was validated by permanent exchanges between private and experimental flocks: it permits, on the one hand to conceive and validate simplified tools such as lactation sampling for fat and protein contents, and SCC, and on the other hand to understand the originality of the dairy selection environment when management decisions are taken at the flock level and not individually, which may induce sustainable indirect genetic responses (feed intake ability, milking speed, once daily milking ability) used by the breeders. This rationalized approach does not preclude the implementation of other solutions to address a strategic and unforeseen new goal, such as scrapie resistance in the 1990’s. For each of the five local breeds, diversification of new breeding objectives (once daily milking ability, functional longevity, milk persistency, resistance to gastrointestinal strongyles) is likely to occur since the 2015 starting of genomic selection in French dairy sheep breeds.

International audience; In sheep, social reactivity and reactivity to humans are relevant behavioral responses that are used to investigate the behavioral adaptation of farm animals to various rearing conditions. Such traits were previously reported as heritable and associated with several QTLs. However, few behavior-related genotype by environment (G x E) interactions have been reported to date. The experiment was performed on 2,989 male and female lambs issued from 30 sires. Every sire had progeny reared under both intensive and extensive conditions. After weaning, all lambs were individually exposed to two standardized behavioral tests. A broad range of behaviors including vocalizations, locomotion, localization, vigilance, and flight distance were assessed. Two complementary statistic approaches, with and without assumptions on the biological significance of behaviors, were performed to investigate social reactivity and reactivity to humans. G x E interactions were investigated based on the genetic correlations estimated for each factor or trait between farming conditions; those significantly different from 1 indicating a G x E. Environmental effects showed that social reactivity and reactivity to humans were higher in intensively reared lambs. The heritability of factors or traits used to measure social reactivity and reactivity to humans was similar in both rearing conditions. Estimated heritabilities were high for vocalizations in response to social isolation, moderate for locomotion and vigilance in response to social isolation, and low for both flight distance to an approaching human and proximity to a motionless human. No significant G x E interaction was found for vocalizations. G x E interactions were found for locomotion, vigilance and flight distance. Genetic correlations between both environments were low to moderate for vigilance, locomotion and flight distance. Vocalization in response to social isolation with or without human presence was identified as a robust trait and could be used to improve sheep sociability, independently of the environment. A G x E interaction was observed for behavioral reactivity to humans. Although moderate, the genetic correlation for this trait between intensive and extensive conditions could be used to select sires in the same environment by taking into account the G x E and to produce in different environments progenies that are less reactive to humans.

National audience; Mastitis is an infectious disease mainly caused by bacteria invading the mammary gland. Genetic control of susceptibility to mastitis has been widely evidenced in dairy ruminants, but the genetic basis and underlying mechanisms are still largely unknown. We describe here the discovery, fine mapping and functional characterization of a genetic variant associated with mastitis in dairy sheep. After implementing genome-wide association studies, we identified a major QTL associated with an elevated milk leukocyte count on ovine chromosome OAR3. Fine mapping of the region, using full sequencing of the genomes of three animals with a 12X coverage, provided one strong SNP candidate that mapped to the coding sequence of a highly conserved gene, suppressor of cytokine signaling 2 (Socs2). The frequency of the allele associated with increased susceptibility to mastitis was 21.7% and the Socs2 genotype explained 12% of the variance of the trait. The point mutation induces the R96C substitution in the SH2 functional domain of SOCS2, i.e. the binding site of the protein to various ligands, as well-established for the growth hormone receptor GHR. Using surface plasmon resonance we show that the R96C point mutation completely abrogated SOCS2 binding affinity for the phosphopeptide of GHR. Additionally, the body size, body weight and milk production in R96C homozygote sheep, were significantly increased by 24%, 18%, and 4.4%, respectively, when compared to wild type sheep, supporting the view that the point mutation causes a loss of SOCS-2 functional activity. Altogether these results provide strong evidence for a causal mutation controlling mastitis in sheep and highlight the major role of SOCS-2 as a tradeoff between the host’s inflammatory response to mammary infections, and body growth and milk production, which are all mediated by the JAK/STAT signaling pathway.; Les mammites sont principalement liées à des infections de la glande mammaire par diverses bactéries. L’existence d’une variabilité génétique naturelle de la résistance des ruminants laitiers aux mammites a été largement établie, mais les gènes sous-jacents restent majoritairement inconnus. Dans cet article, nous rapportons les résultats de détection, de cartographie fine et de caractérisation fonctionnelle d’un variant génétique associé à la prédisposition aux mammites chez les ovins laitiers. En premier lieu, une analyse d’association basée sur le génotypage de 1009 béliers avec la puce Illumina 50K OvineSNP50Beadchip a permis d’identifier une région QTL, associée à des concentrations de cellules somatiques (CCS) élevées, sur le chromosome ovin OAR3. La cartographie fine de la région basée sur le séquençage complet de 3 animaux chez qui les allèles ségrégeaient a permis d’identifier un SNP candidat localisé dans la séquence codante d‘un gène hautement conservé dans le règne animal, Suppressor Of Cytokine Signaling 2 (Socs2). La fréquence de l’allèle associé à des CCS élevés est de 21,7% et le « génotype Socs2» explique 12% de la variance du caractère dans la population où il a été identifié. La mutation induit une substitution R96C dans le domaine fonctionnel SH2 de SOCS-2, le site de fixation de la protéine à de nombreux ligands tels que le récepteur à l’hormone de croissance (GHR). A l’aide d’un test fonctionnel basé sur la résonance des plasmons de surface, nous avons montré que la mutation R96C abroge l’affinité de SOCS-2 pour la tyrosine phosphorylée du domaine intracellulaire de GHR. Par ailleurs, nous avons montré que la croissance et la taille à l’âge adulte des brebis portant l’allèle muté étaient supérieures à celles des brebis de génotype sauvage, en adéquation avec l’hypothèse d’une invalidation de la fonction de SOCS-2. De plus, la mutation est également associée à une production laitière supérieure. L’ensemble de ces résultats conforte le fait que la mutation identifiée est probablement responsable du QTL pour les CCS sur OAR3. Ces résultats suggèrent un rôle de SOCS-2 dans le contrôle de l’inflammation médié par la voie de signalisation JAK/STAT et suggèrent un potentiel effet pléiotropique de cette mutation sur la croissance et les caractères de production.

National audience

Les mammites sont principalement liées à des infections de la glande mammaire par diverses bactéries. L’existence d’une variabilité génétique naturelle de la résistance des ruminants laitiers aux mammites a été largement établie, mais les gènes sous-jacents restent majoritairement inconnus. Dans cet article, nous rapportons les résultats de détection, de cartographie fine et de caractérisation fonctionnelle d’un variant génétique associé à la prédisposition aux mammites chez les ovins laitiers. En premier lieu, une analyse d’association basée sur le génotypage de 1009 béliers avec la puce Illumina 50K OvineSNP50Beadchip a permis d’identifier une région QTL, associée à des concentrations de cellules somatiques (CCS) élevées, sur le chromosome ovin OAR3. La cartographie fine de la région basée sur le séquençage complet de 3 animaux chez qui les allèles ségrégeaient a permis d’identifier un SNP candidat localisé dans la séquence codante d‘un gène hautement conservé dans le règne animal, Suppressor Of Cytokine Signaling 2 (Socs2). La fréquence de l’allèle associé à des CCS élevés est de 21,7% et le « génotype Socs2» explique 12% de la variance du caractère dans la population où il a été identifié. La mutation induit une substitution R96C dans le domaine fonctionnel SH2 de SOCS-2, le site de fixation de la protéine à de nombreux ligands tels que le récepteur à l’hormone de croissance (GHR). A l’aide d’un test fonctionnel basé sur la résonance des plasmons de surface, nous avons montré que la mutation R96C abroge l’affinité de SOCS-2 pour la tyrosine phosphorylée du domaine intracellulaire de GHR. Par ailleurs, nous avons montré que la croissance et la taille à l’âge adulte des brebis portant l’allèle muté étaient supérieures à celles des brebis de génotype sauvage, en adéquation avec l’hypothèse d’une invalidation de la fonction de SOCS-2. De plus, la mutation est également associée à une production laitière supérieure. L’ensemble de ces résultats conforte le fait que la mutation identifiée est probablement responsable du QTL pour les CCS sur OAR3. Ces résultats suggèrent un rôle de SOCS-2 dans le contrôle de l’inflammation médié par la voie de signalisation JAK/STAT et suggèrent un potentiel effet pléiotropique de cette mutation sur la croissance et les caractères de production., Mastitis is an infectious disease mainly caused by bacteria invading the mammary gland. Genetic control of susceptibility to mastitis has been widely evidenced in dairy ruminants, but the genetic basis and underlying mechanisms are still largely unknown. We describe here the discovery, fine mapping and functional characterization of a genetic variant associated with mastitis in dairy sheep. After implementing genome-wide association studies, we identified a major QTL associated with an elevated milk leukocyte count on ovine chromosome OAR3. Fine mapping of the region, using full sequencing of the genomes of three animals with a 12X coverage, provided one strong SNP candidate that mapped to the coding sequence of a highly conserved gene, suppressor of cytokine signaling 2 (Socs2). The frequency of the allele associated with increased susceptibility to mastitis was 21.7% and the Socs2 genotype explained 12% of the variance of the trait. The point mutation induces the R96C substitution in the SH2 functional domain of SOCS2, i.e. the binding site of the protein to various ligands, as well-established for the growth hormone receptor GHR. Using surface plasmon resonance we show that the R96C point mutation completely abrogated SOCS2 binding affinity for the phosphopeptide of GHR. Additionally, the body size, body weight and milk production in R96C homozygote sheep, were significantly increased by 24%, 18%, and 4.4%, respectively, when compared to wild type sheep, supporting the view that the point mutation causes a loss of SOCS-2 functional activity. Altogether these results provide strong evidence for a causal mutation controlling mastitis in sheep and highlight the major role of SOCS-2 as a tradeoff between the host’s inflammatory response to mammary infections, and body growth and milk production, which are all mediated by the JAK/STAT signaling pathway.

National audience