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.

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 reactivity 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 findings 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.

Background Current trends in sheep farming practices rely on animals with a greater level of behavioral autonomy than before, a phenotype that actively contributes to the sustainability of animal production. Social reactivity and reactivity to humans are relevant behavioral traits in sheep, known for their strong gregariousness and weak tolerance to handling, which have previously been reported with moderate to high heritabilities. To identify loci underlying such behaviors, we performed a genome study in Romane lambs. Results The experiment was carried out on 934 male and female lambs allocated into 9 half-sib families (average of 103 lambs per family) and reared outside. After weaning, all the lambs were individually exposed to 4 standardized behavioral tests combining social isolation, exposure to humans or handling, confinement and novelty (i.e. arena test, corridor test, isolation box test, shearing test). A broad range of behaviors including vocalizations, locomotion, vigilance and flight distance, as well as the cortisol response to handling, were collected. All lambs were genotyped using the Illumina OvineSNP50 BeadChip. QTL detection was performed by linkage, association and joint linkage and association analyses using the QTLmap software. Five main QTL regions were identified on sheep chromosomes ( Ovis Aries Region, OAR) 12, 16, 19, 21 and 23 among many other QTLs with small to moderate effects. The QTLs on OAR12, 16 and 21 showed significant associations with social reactivity. The QTLs on OAR19 and 23 were found to be associated with reactivity to humans. No overlapping QTLs were identified for the different traits measured in the behavioral tests, supporting the hypothesis that different genetic factors influence social reactivity and tolerance to humans. Conclusion The results of this study using ovine SNP data suggest that in domestic sheep the behavioral responses to social separation and exposure to humans are under polygenic influence. The most relevant QTLs reported in the present study contain interesting candidate genes previously described to be associated with various emotional and social behaviors in mammals.

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 locomotor 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.

Sheep industry is located in both favorable environment (on meadows or associated with grain industry) and in harsh environment. In France sheep industry has decreased in the plains and is now mainly located in harsh environment. Harsh can be wet in marshlands or in meadows (Western France), cold in mountains (Alps, Central Massif, Pyrenees) or dry in southern areas (Causses, Provence or Corsica). Selection strategies for harsh environment could be to select for production traits in situ or to identify adaptive traits and select for them together with production traits. Identification of adaptive traits has been a long way research program and consistent results are about to be reached in our topic of sheep breeding.

La mise en evidence de la mutation d'hypermuscularite du Texel Belge est le fruit d'une collaboration entre plusieurs equipes de l'INRA et l'Universite de Liege. Elle a implique la mobilisation de ressources experimentales, de mesures fines des caracteres, les apports de la genetique quantitative et moleculaire. Le mecanisme est original puisque la mutation n'affecte pas la region codante d'un gene et ne modifie pas de proteine. La mutation cree un site pour deux microARNs venant perturber l'activite de l'ARN transcrit, et donc la synthese de la myostatine. La cause de l'hypertrophie est l'inhibition de la myostatine au stade foetal. L'effet de la mutation est modere par rapport a ses equivalentes en bovin: son interet est d'accroitre la conformation sans perturber l'equilibre de l'animal. Ainsi l'organisation de selection du GEBRO a entrepris l'introgression de cette mutation dans sa population Lacaune. Le programme produit actuellement les premiers reproducteurs homozygotes 15/16 Lacaune.

La selection genetique d’animaux resistants aux strongles gastro-intestinaux est une des reponses possibles au developpement des resistances aux anthelminthiques dans les elevages ovins. Sa mise en œuvre pratique est possible des maintenant grâce a l’estimation de l’intensite de l’excretion d’œufs dans les matieres fecales en infestations naturelles ou artificielles. Toutefois, cette technique est trop lourde a developper sur de tres grands effectifs. La selection assistee par marqueurs proches de genes de resistance ou encore mieux par les mutations des genes eux-memes pourrait predire la valeur genetique d’un individu a la naissance sans passer par une mesure ulterieure de son phenotype. Les outils moleculaires de cette selection sont actuellement a l’etude. Les limites potentielles de la selection genetique sur la resistance aux nematodes gastro-intestinaux, comme une plus grande sensibilite a d’autres pathogenes (virus, bacteries ou protozoaires) ou une adaptation des parasites a des hotes resistants, sont abordees et discutees.

La sélection génétique d’animaux résistants aux strongles gastro-intestinaux est une des réponses possibles au développement des résistances aux anthelminthiques dans les élevages ovins. Sa mise en oeuvre pratique est possible dès maintenant grâce à l’estimation de l’intensité de l’excrétion d’oeufs dans les matières fécales en infestations naturelles ou artificielles. Toutefois, cette technique est trop lourde à développer sur de très grands effectifs. La sélection assistée par marqueurs proches de gènes de résistance ou encore mieux par les mutations des gènes eux-mêmes pourrait prédire la valeur génétique d’un individu à la naissance sans passer par une mesure ultérieure de son phénotype. Les outils moléculaires de cette sélection sont actuellement à l’étude. Les limites potentielles de la sélection génétique sur la résistance aux nématodes gastro-intestinaux, comme une plus grande sensibilité à d’autres pathogènes (virus, bactéries ou protozoaires) ou une adaptation des parasites à des hôtes résistants, sont abordées et discutées.

Selective breeding of animals resistant to gastrointestinal strongyles is one of the possible answers to increasing anthelmintic resistance in sheep farming. It is currently feasible, based on the estimation of the faecal egg count in natural or experimental infections. However, this technique is too complicated for very large herds. The identification of genetic markers or mutations associated with resistance could predict the genetic value of each individual without measuring phenotypes. Molecular tools for this genetically-assisted selective breeding are currently under development. Potential limits of selective breeding for host resistance to gastrointestinal nematodes, such as an increased susceptibility to other pathogens (virus, bacteria and protozoa) or a possible adaptation of these parasites to resistant hosts, are discussed.

The slaughter period is very complex and may represent different types of stress for the animal. The way and extent animals react to these stress factors depend on their individual emotional reactivity. The objective of the present study was to determine in sheep relationships between reactivity profiles measured during rearing, plasma cortisol levels in blood collected at exsanguination, and metabolic activity in the post-mortem muscle. During the rearing period INRA401 lambs (n=267) showed coherence in their responses to situations representing different contexts of novelty, social isolation and presence of man. Vigilance and high-pitched bleating were the most often occurring behaviours. Highest levels of these behaviours were observed during novelty and social isolation. Lambs with higher plasma cortisol levels at exsanguination produced meat with lower pH 3h (r=−0.19, p=0.003) and 24h post-mortem (r=−0.13, p=0.05). Multiple regression analysis found that more socially attracted lambs and lambs performing more high-pitched bleating had higher muscle temperature 3h post-mortem (p<0.001), explaining 23.5% of variability. More vigilant lambs had higher pH (r=0.14, p=0.02) 3h post-mortem. Multiple regression including both cortisol and vigilance as explanatory variable was significant (p<0.01) and explained 12.8% of variability of pH 3h post-mortem. In the present study, slaughter day, that is, day-to-day variations in the slaughter context, explained 18.4% of the variability in cortisol levels and 25.0–72.7% of variability in post-mortem muscle measurements. When analyses were based on averages per category created according to cortisol levels at exsanguination, to reduce the variability due to slaughter days, behavioural traits (vigilance and social attractiveness of flock-mates) explained statistically about 50% of variability in cortisol levels at exsanguination, and pre-slaughter cortisol levels explained up to 50% of variability of ultimate pH. Relationships between post-mortem muscle metabolism and expressions of social distress and reactivity to novelty suggest that reactivity profile may predict stress reactions during slaughter period and that social disturbances and novel environment in the slaughterhouse may be major causes of stress.