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The study was to focus on the relationship between wave motion (mass sperm motility, measured by a mass sperm motility score, manually assessed by artificial insemination (AI) center operators) and fertility in male sheep. A dataset of 711,562 artificial inseminations performed in seven breeds by five French AI centers during the 2001–2005 time period was used for the analysis. Factors influencing the outcome of the insemination, which is a binary response observed at lambing of either success (1) or failure (0), were studied using a joint model within each breed and AI center (eight separate analyses). The joint model is a multivariate model where all information related to the female, the male and the insemination process were included to improve the estimation of the factor effects. Results were consistent for all analyses. The male factors affecting AI results were the age of the ram and the mass motility. After correction for the other factors of variation, the lambing rate increased quasi linearly from three to more than ten points with the mass sperm motility score depending on the breed and the AI center. The consistency of the relationship for all breeds indicated that mass sperm motility is predictive of the fertility resulting when sperm are used from a specific ejaculate. Nonetheless, predictability could be improved if an objective measurement of mass sperm motility were available as a substitute for the subjective scoring currently in use in AI centers.

Séance : Mixité dans les systèmes d’élevage, polyculture élevage, exploitation et territoire; International audience; One of the principles of agroecology is that the management of animal and plant diversity within livestock farms can enhance their sustainability. To go beyond this theoretical principle, we analyze the farm operation and performance of multi-species livestock farms, i.e. farms where at least two animal species are raised. In grassland-based systems, the complementarity of sheep, cattle and horse grazing behaviour reduces the use of feed concentrates, especially for sheep. Parasite dilution in mixed grazing systems benefits small ruminants and horses, and makes it possible to reduce the number of anthelmintic treatments. Adding a small monogastric enterprise to a beef or dairy system makes it possible to value farm co-products (whey...); milk processing is often associated with on-farm processing and opens up the possibility of short-distribution channels of diversified food baskets, which enhance farm viability. Work organization plays a key role in the way different species are integrated on the same farm. Rather than focusing on the maximization of within-farm diversity only, what matters is to reach an overall consistency of the system that the farmer is able to manage. Finally, we discuss the obstacles to the scaling-out of multi-species livestock farms, linked to a socioeconomic system built to benefit from the economies of scale offered by specialisation. To overcome these obstacles, we propose levers upstream (innovating for multipurpose equipment and infrastructures), downstream (reorganizing the collect chain) and around these farms (revisiting training and advice) that must be thought out in a coupled manner.; L’agroécologie stipule que la gestion de la diversité animale et végétale au sein des exploitations d’élevage renforce leur durabilité. Pour aller au-delà de ce principe théorique, nous analysons ici le fonctionnement et les performances d’exploitations de polyélevage, c’est-à-dire de fermes dans lesquelles sont élevées au moins deux espèces animales. Dans les systèmes herbagers, la complémentarité des modes de pâturage des ovins, des bovins et des chevaux permet de réduire le recours aux aliments concentrés, en particulier pour les ovins. La dilution des parasites digestifs en pâturage mixte profite aux petits ruminants et aux chevaux, et permet d’envisager de réduire la fréquence des traitements anthelminthiques. Un atelier monogastrique de petite taille permet de valoriser les co-produits (petit lait...) ; la transformation laitière, créatrice de valeur ajoutée, et les faibles volumes de viande commercialisés sont bien adaptés à la vente en circuits courts. L’organisation du travail entre toujours en ligne de compte dans la manière d’articuler différentes espèces au sein d’une même exploitation. Plutôt que de vouloir maximiser coûte que coûte la diversité au sein du système, il s’agit avant tout de rechercher une cohérence d’ensemble que les éleveurs puissent gérer. Nous discutons enfin des freins au déploiement des fermes de polyélevage, liés à un système socioéconomique construit pour bénéficier des économies d’échelle offertes par la spécialisation. Pour dépasser ces freins, nous proposons des leviers en amont (innover pour des équipements et infrastructures polyvalentes), à l’aval (réorganiser la logique de collecte), et autour des exploitations d’élevage (revisiter la formation et le conseil) qui doivent être pensés de manière couplée.

Séance : Qualité des produits; International audience; This study proposes an adaptation of the methodologies of Botreau et al. (2018) and Rey-Cadilhac et al. (2021) forthe multi-criteria assessment of milk intended for the manufacture of raw milk cheese, concerning the environmentalimpacts of milk production and the quality of the milk obtained. A main contribution is to rely on rapid and operationalanalysis methods on a larger scale: mid-infrared and fluorescence spectroscopies milk analyzes and CAP'2ER®diagnostic results of the farm. On 15 grassland dairy farms located in Cantal, representative of three types ofadaptation to the territorial context, the multi-criteria evaluation model tested in this study proved to be sensitive.Among the 4 components of milk quality and the 5 components of environmental performance analyzed, only thehealth component of quality showed significant differences between the different farm profiles. A significant andpositive correlation is found between the risk of eutrophication and risk for health. Other trending correlations areanalyzed between the components of milk quality and environmental performance, in association with agronomicpractices.; La présente étude propose une adaptation des méthodologies de Botreau et al. (2018) et Rey-Cadilhac et al. (2021)pour l’évaluation multicritère du lait destiné à la fabrication de fromage au lait cru, concernant les impactsenvironnementaux de la production du lait et la qualité du lait obtenu. Une des contributions de ce travail est lerecours à des méthodes d’analyse rapides et opérationnelles à large échelle : analyses du lait en spectroscopies enmoyen infra-rouge et fluorescence, et résultats de diagnostic CAP'2ER® de l'exploitation. Sur 15 fermes laitièresherbagères situées dans le Cantal, représentatives de trois types d’adaptation au contexte territorial, le modèled’évaluation multicritère testé dans cette étude s’est avéré sensible. Parmi les 4 composantes de la qualité du lait etles 5 composantes de la performance environnementale analysées, seule la composante santé de la qualité du laitprésente des différences significatives entre les différents types de fermes. Une corrélation significative et positiveest établie entre risque d’eutrophisation et risque pour la santé. D’autres corrélations en tendance sont analyséesentre les composantes de la qualité du lait et de la performance environnementale, en association avec les pratiquesagronomiques.

Séance : Mixité dans les systèmes d’élevage, polyculture élevage, exploitation et territoire; International audience; Few studies focus on the small cultivated plains of livestock regions and on relationships between livestock farming and cereals cultivating to identify their particular forms and dynamics. This is why thirty surveys of breeders in two small cultivated areas of Auvergne-Rhône-Alpes region (France) were realized in 2021. Their analysis highlights three contrasted breeder profiles, present in each of the two different cultivated areas, according to farming practices of crop-livestock relations: the first profile who supplement vegetal needs through exchanges with another farm, the second one who supplement manure needs through such exchanges, the third one who sell vegetal matters. Each profile also has a specific overall strategy for the development and valuation of their animal productions. This shows that the development of practices for crop-livestock relations requires to consider the diversity of livestock farm strategies in terms of matters exchanges, trade and trade and marketing in these cultivated areas.; RESUME-Peu de travaux s'intéressent aux petites plaines cultivées des régions d'élevage et aux relations cultures-élevages développées dans ce type de zones pour en repérer les formes et dynamiques particulières. Une trentaine d'enquêtes réalisées en 2021 auprès d'éleveurs de deux petites zones cultivées d'Auvergne-Rhône-Alpes permet de caractériser la diversité des élevages quant à leurs relations aux cultures. L'analyse met en évidence trois profils d'éleveurs dans chacune des deux zones et montre qu'ils se distinguent par leurs échanges avec d'autres exploitations. Un premier profil correspond à ceux qui complètent des besoins en végétaux par ces échanges, le deuxième à ceux qui complètent des besoins de fumure, le troisième à ceux qui vendent des matières végétales. Chacun des profils a aussi une stratégie globale de développement et de valorisation de l'élevage spécifique. Ceci montre que le développement des relations cultures-élevages passe par la prise en compte de cette diversité de stratégie des élevages, en termes d'échanges et de commercialisation dans ces zones cultivées.

Séance : Bien-être animal; International audience; Animal behaviour is very sensitive to any external disturbance or change in the animal internal state. We sought to predict and classify a wide range of health, stress and physiological states from daily activity of dairy cow. We had six datasets (total, 122,000 cows*days). The caretakers noted the condition of the cows: illness, oestrus, calving, disturbances (handling, mixing. Cows were equipped with sensors to estimate the duration of activities - eating, resting, in the alleys - from which the activity level was calculated. We modelled the rhythm of activity by the Fourier transform (Harmonics 0 and 1). If the difference between the models obtained during 2 series of 24 h is higher than a certain threshold, there is a strong chance that a particular event has occurred: illness, stress, heat, farrowing. The change takes place before the caretakers spot the event. Next, we applied random forest to attributes describing the 24 h activity series (minimum, maximum, average, autocorrelations...). We correctly classify 99% of the control series (= very rare false positive) and in an episode surrounding a disease or a reproductive event, the probability of correctly classifying at least one series varies from 94 to 100%. Machine learning applied to time series seems therefore a very powerful tool to analyse the behaviour of animals and diagnose its internal state.; Le comportement d’un individu est très sensible à toute perturbation extérieure ou modification de l’état interne. Nous avons cherché à prédire et à classer un large éventail d'états de santé, de stress et d'états physiologiques à partir de l'activité quotidienne de vaches laitières. Nous disposions de six jeux de données (au total 122 000 vaches*jours). Les soigneurs notaient l'état des vaches : maladie, oestrus, vêlage, perturbations (manipulations, mélange). Les vaches étaient équipées de capteurs permettant d’estimer la durée des activités - manger, se reposer, dans les couloirs – à partir desquelles était calculé le niveau d’activité. Nous avons modélisé le rythme d’activité par des transformées de Fourier (Harmoniques 0 et 1). Si l’écart entre les modèles obtenus au cours de 2 séries de 24 h est supérieur à un certain seuil, il y a de fortes chances qu’un événement particulier soit survenu : maladie, stress, chaleurs, mise-bas. Le changement s’opère avant que les soigneurs repèrent l’évènement. Ensuite, nous avons appliqué le random forest à des attributs décrivant les séries d’activité de 24 h (minimum, maximum, moyenne, autocorrélations…). Nous classons correctement 99% des séries témoins (= quasiment pas de fausse alertes) et dans un épisode qui entoure une maladie ou un événement reproductif, la probabilité de classer correctement au moins une série varie de 94 à 100%. L'apprentissage automatique appliqué à des séries temporelles semble donc un outil très puissant pour analyser le comportement des animaux et diagnostiquer son état interne.

International audience; For a long time, descriptive and experimental studies have shown that agricultural practices affect plant diversity in permanent grasslands. More recently, landscape organization and, more particularly, spatial organization of agroecological structures (AES) was identified as a major factor affecting plant diversity. AES are semi-natural elements, such as hedges, isolated trees, etc. The objective of this study was to evaluate the mixed effects of both agricultural practices and spatial organization of landscape on taxonomic and functional diversity in different French farming systems. We focused on twelve livestock farms distributed along two gradients: i) intensity of agricultural practices, and ii) density of AES on farm territory. In each farm, four types of permanent grasslands were selected in which variables of agricultural practices (date of mowing, livestock rate, fertilization), landscape (AES categories, AES density, AES connectivity) and floristic composition are sampled. Variance partitioning analysis showed that taxonomic diversity is mainly due to landscape variables, like density of hedges and diversity of AES included in a 300 m buffer zone around the floristic survey. The variance of functional indices depended both agricultural practices (livestock and mineral fertilization) and landscape variables such as density of hedges.

Bulk milk samples were collected from four French regions to study the potential capability of mid-infrared (MIR) and near-infrared (NIR) spectroscopy data to differentiate milk according to the feeding system, breed of cow and altitude of the farm. The MIR method demonstrated an excellent capability to distinguish milk from hay- and pasture-based systems and those from maize silage- and pasture-based systems. The MIR method did not exhibit the same capability concerning the discrimination of milk from hay- and maize silage-based systems. A similar trend was observed with the NIR method but with lower efficiency. The two infrared methods did not satisfactorily discriminate milk from different cow breeds. Significant differences (P < 0.05) between methods in the proportion of correctly classified samples according to the feeding system and breed were reported, whereas no significant differences were found between the methods concerning the discrimination of lowland versus upland samples.

Improvement of reproduction in dairy cows has become a major challenge in dairy production. We have recently shown that dairy cows carrying the 'fertil-' haplotype for one quantitative trait locus (QTL), affecting female fertility and located on the bovine chromosome 3, had a significantly lower conception rate after the first artificial insemination than cows carrying the 'fertil+' haplotype. The objective of this paper was to study other phenotypic modifications linked to this QTL. In the present study, 23 'fertil+' and 18 'fertil-' cows were characterized for live weight, milk production, food intake, eating behaviour and plasma metabolites. These parameters were measured during the first lactation, from calving to 40 weeks postpartum (wkpp). In the first 7 weeks of lactation, 'fertil+' primiparous cows had a significantly higher live BW and milk production than 'fertil-' cows. Dry matter intake tended to be slightly higher for 'fertil+' than for 'fertil-' primiparous cows in this period. However, energy balance was similar for the two haplotypes in the whole lactation, except in the first wkpp, and consequently, could not explain their different fertility. The major observation concerned the eating behaviour. 'Fertil+' primiparous cows had a significantly lower eating rate than 'fertil-' cows during the 40 weeks of lactation. In parallel, 'fertil+' cows spent significantly more time at the feeder for a similar number of visits than 'fertil-' cows. Furthermore, no differences in plasma concentrations of non-esterified fatty acids and insulin were observed between the two haplotypes. Plasma glucose was significantly lower in 'fertil+' than in 'fertil-' cows in the second wkpp. Taken together, our results show that 'fertil+' and 'fertil-' dairy cows, with different fertility, have also different eating behaviour without any variation in energy balance, except in the first week of lactation.

We have previously shown that Holstein cows selected for their homozygous favorable ("fertil+") or unfavorable ("fertil-") haplotype at one quantitative trait loci (QTL) of female fertility located on chromosome 3 (QTL-F-Fert-BTA3) had a different success rate 35 and 90 days after the first artificial insemination. To determine whether the lower fertility in "fertil-" animals could be related to oocyte quality, we analyzed the embryo development rate in vitro and the oocyte meiotic maturation in vivo in "fertil+" and "fertil-" heifers. In vitro maturation and fertilization of immature oocytes recovered by ovum pick-up from "fertil+" and "fertil-" heifers resulted in similar cleavage and blastocyst rates in the two haplotypes. However the percentage of expanded blastocysts and the number of cells per blastocyst were significantly higher in "fertil+". Oocytes from presumptive preovulatory follicles were analyzed after ovarian stimulation. A similar rate of immature (from prophase to metaphase-I) and mature oocytes (metaphase-II) was obtained in the two haplotypes, whereas a significantly higher percentage of oocytes from metaphase-I to metaphase-II was observed in "fertil+" compared to "fertil-" heifers. Since cumulus cells (CCs) could reflect the developmental competence of oocytes, we analyzed the expression of seven genes included in the QTL-F-Fert-BTA3 using real-time PCR in bovine CCs after in vivo or in vitro maturation, as a model of higher and lower competence, respectively. Transcript levels of TAGLN2, EEF1A1 and PIGM were higher in CCs after in vitro maturation (IVM) compared to in vivo maturation, whereas no difference was observed for IFI16, KIRREL, SPTA1 and PEX19 expression. The expression levels of all these genes in in preovulatory CCs were not significantly different between "fertil+" and "fertil-" heifers. In conclusion, the lower fertility of "fertil-" females could be partially due to a lowest quality of the oocytes and consequently of preimplantation embryo development.

Improving feed efficiency is an important issue for beef producers. To study its feasibility, 588 Charolaisyoung bulls were fattened in four experimental stations, from 2015 to 2019, with either corn silage or grasssilage. Feed conversion efficiency (FCE) was higher for animals fattened with corn silage (0,164 kg/kgMS vs 0,146 kg/kg MS). Efficient animals better used diet nitrogen and had a lower natural abundance of15N in plasma. Genetic study showed that feed efficiency is heritable, but some correlations wereunfavorable with performance traits. A genetic selection of beef cattle is possible with a selection indexthat combined both feed efficiency and production.; Sélectionner sur l’efficience alimentaire est un enjeu important pour les éleveurs bovins allaitants. Pourétudier sa faisabilité, 588 jeunes bovins ont été engraissés dans quatre stations expérimentales, de 2015à 2019, avec de l’ensilage de maïs ou d’herbe ad libitum. L’efficience de conversion des aliments (EA)était supérieure chez les animaux engraissés avec l’ensilage de maïs (0,164 kg/kg MS contre0,146 kg/kg MS) lié à des croissances élevées. Les animaux efficients valorisaient mieux l’azotealimentaire et avaient une abondance naturelle en 15N dans le plasma moindre. Les analyses génétiquesont montré que l’efficience alimentaire est héritable, mais certaines corrélations sont non favorables avecles performances. Une amélioration génétique du troupeau allaitant est possible via un index de sélectioncombinant efficience alimentaire et production.

Session: Qualité des produits et Sécurité des aliments; International audience; In order to achieve the ambitious objectives set at the "Etats Généraux de l'Alimentation", the meatsupply chain must encourage the development of meat sold under quality labels. The meat sector's commitment tomeeting numerous societal challenges also requires a multitude of indicators to be taken into account. At theanimal scale, three of the seven properties of meat quality described by the collective expertize "Quality of food ofanimal origin" have been detailed in this communication: organoleptic, nutritional and commercial properties. Areview of the literature enabled to establish a list of indicators to characterize these three properties. The objectiveof this communication was then to introduce the principle of multi-criteria modelling to create specifications inaccordance with the preferences of decision-makers. The potential of the Analytic Hierarchical Process (AHP) tohelp the decision-maker to set the weight of each criterion with a simple methodology was explained. Despite asimplification of the allocation of weights, it was pointed out that the "classic" weighting aggregation methods do notallow for agreement with the realities on the ground. Conversely, ELECTRE-type methods of out-ranking seempromising for assessing beef quality thanks to "veto" thresholds avoiding the phenomenon of compensation.; Pour atteindre les objectifs ambitieux fixés lors des états généraux de l’alimentation, la filière doitfavoriser le développement de viande vendue sous signes de qualité. L’engagement de la filière à répondre à denombreux enjeux sociétaux nécessite aussi la prise en compte d’une multitude d’indicateurs. À l’échelle del’animal, trois des sept propriétés de la qualité de la viande, décrites par l’expertise collective « Qualité desaliments d’origine animale » ont été détaillées dans cette communication : les propriétés organoleptique,nutritionnelle et commerciale. Une revue de la littérature a permis d’établir une liste d’indicateurs permettant decaractériser ces trois propriétés. L’objectif de cette communication a ensuite été d’introduire le principe de lamodélisation multicritère pour créer des cahiers des charges en accord avec les préférences des décideurs. Lepotentiel de l’Analytic Hierarchical Process (AHP) permettant d’aider le décideur à fixer le poids de chaque critèreavec une méthodologie simple a été expliqué. Malgré une simplification de l’attribution des poids, il a été rappeléque les méthodes d’agrégation par pondération « classique » ne permettent pas de s’accorder avec les réalités duterrain. A l’inverse, les méthodes de surclassement du type ELECTRE semblent prometteuses pour évaluer laqualité de la viande bovine grâce à des seuils « véto » évitant le phénomène de compensation.

Séance : Le Microbiome; International audience; Ruminants, similar to humans and other mammals, host trillions of symbiotic microbes, the microbiota,in their skin, digestive, respiratory and genital tracts. The composition and functions of these microbiotasdepends on their location. A particularity of ruminants is the presence of a specialized microbiota in therumen composed by bateria (50 % of biomass), protozoa, archea and fungi. Omics approaches,particularly new-generation sequencing, have made possible to characterize members of the microbiota,their genes and their activities. The ruminal microbiota, located upstream of the absorption sites, has acentral role in ruminant nutrition. Ruminant production is also impacted by the gut microbiota and themicrobiota associated to the udder skin. The intestinal microbiota is diverse and specific to the segmentsunder consideration. Finally, the microbiota of the udder skin is a major reservoir of the microbialdiversity of raw milk. These different microbes interact with each other and with their host under theinfluence of various factors of variation. Diet is the main factor in the modulation of gut microbiota,whereas feeding practices in early life also influence the implantation kinetics and structure of themicrobiota. The living environment of the animal, in connection with diet, has a particular impact on themicrobiota of the udder skin. Recent studies show a potential genetic control by the host of its microbialcommunities. Also, there is accumulated evidence of the links between microbiota and animal health,feed efficiency, performance, products quality and greenhouse gas production. Such findings justify thegrowing interest of farmers on animal microbiotas and their modulation.; Les ruminants, tout comme l’Homme et les autres mammifères, hébergent des billions de microbessymbiotiques, constituant les « microbiotes » de la peau, des voies digestives, respiratoires et génitales.La composition et les fonctions de ces microbiotes dépendent de leur emplacement. Une particularitédes ruminants est la présence d'un microbiote spécialisé dans le rumen, composé principalement debactéries (50 % de la biomasse), de protozoaires, d’archées et de champignons. L’application desapproches omiques, en particulier le séquençage de nouvelle génération a permis de caractériser lesmembres du microbiote, leurs gènes et leurs activités. Le microbiote ruminal, situé en amont des sitesd'absorption, joue un rôle central dans la nutrition des ruminants. La production des ruminants est aussiparticulièrement influencée par le microbiote intestinal et le microbiote associé à la peau de la mamelle.Les populations microbiennes intestinales sont diversifiées et leur composition est spécifique dessegments considérés. Enfin, le microbiote cutané de la mamelle est un réservoir important de la diversitémicrobienne du lait cru. Ces différents microbes interagissent entre eux et avec leur hôte sous l'influencede divers facteurs de variation. Le régime alimentaire est le principal facteur de modulation desmicrobiotes digestifs, tandis que les pratiques d'alimentation au début de la vie influencent égalementla cinétique d'implantation et la structure de ces microbiotes. Le milieu de vie de l'animal, en relationavec l'alimentation, a un impact particulier sur le microbiote cutané mammaire. Des études récentesmontrent un contrôle génétique potentiel par l'hôte de ses communautés microbiennes. En outre, ilexiste une accumulation de preuves des liens entre le microbiote et la santé animale, l'efficacité del'alimentation, les performances, la qualité des produits et la production de gaz à effet de serre. Cesconstatations justifient l'intérêt croissant des éleveurs pour les microbiotes des animaux et leurmodulation.

International audience; The ability of mid-infrared spectroscopy (MIR) to predict indicators (i) of diet composition in dairy herds and (ii) forthe authentication of the cow-feeding restrictions included in the specification of two Protected Designation ofOrigin (PDO) cheeses (Cantal and Laguiole) was tested on 7607 bulk milk spectra from 1355 farms located in theFrench Massif Central. For each milk sample, the corresponding cow diet composition was obtained through onfarm surveys between April 2018 and March 2019. Cow diet composition varied largely (from full grazing forextensive farming systems to corn silage-based diets). The database was divided into a calibration (n = 6107) andvalidation (n = 1500) sets. Partial least square regression and discriminant analysis were used to predict theproportion of different feedstuffs in the cows’ diets and to authenticate the cow-feeding restrictions for the PDOcheese specifications, respectively. The pasture proportion in the cows’ diets was predicted by MIR with an R2 inexternal validation (R2V) = 0.81 and a standard error of prediction (SEP) of 11.7% dry matter. Pasture + hay, cornsilage, conserved herbage, fermented forage and total herbage proportions were predicted with a R2V > 0.61 and aSEP < 14.8%. The discrimination models for pasture presence, pasture ≥ 50% and pasture ≥ 57% in the cows’diets achieved an accuracy and specificity ≥ 90%. A sensitivity and precision > 80% were observed for all modelsincluding pasture proportion in cow diet. An accuracy ≥ 80% was also observed for pasture + hay ≥ 72%, herbage≥ 50%, pasture + hay ≥ 25%, absence of fermented herbage, absence of corn silage and corn silage ≤ 30% in thecows’ diets, but for several models, either the sensitivity or precision was lower than the accuracy. Models built withrespect to all the criteria of the feeding restrictions of PDO cheese specifications achieved an accuracy, specificity,sensitivity and precision > 90%. Both the regression and discriminant MIR models for bulk milk can provide usefulindicators of cow diet composition and PDO cheese specifications to producers and consumers; L’aptitude de la spectroscopie dans le moyen infrarouge (MIR) appliquée sur des laits de mélange pour 1) prédirela composition de la ration des troupeaux laitiers et 2) authentifier des pratiques des cahiers des charges desfromages AOP Cantal et Laguiole, a été testée. Les spectres MIR de 7607 laits de mélange AOP et non AOP de larégion ont été associés aux données d’enquêtes sur l’alimentation correspondantes (obtenues entre avril 2018 etmars 2019), afin de constituer la base des données. La composition de la ration était très variable, allant de rations100% pâturage, à des rations à base d’ensilage de maïs (jusqu’à 74%). La base de données a été divisée en deuxpour l’étalonnage (n = 6107) et la validation (n = 1500). Des modèles de régression « partial least squares » et desanalyses discriminantes ont été utilisés pour prédire la composition de la ration en pourcentage de matière sèche(MS) et pour authentifier les critères d’alimentation inclus dans les cahiers des charges des deux AOP,respectivement. La proportion d’herbe pâturée dans la ration a été prédite avec un modèle caractérisé par uncoefficient de détermination en validation externe (R2V) de 0,81 et une erreur standard de prédiction (SEP) de 11,7%. Les proportions de pâturage + foin, d’ensilage de maïs, d’herbe conservée, de fourrages fermentés et d’herbetotale ont été prédites par des modèles ayant des R2V > 0,61 et SEP < 14,8%. Les modèles d’analysesdiscriminantes pour la présence du pâturage, la proportion de pâturage ≥ 50% et ≥ 57% ont montré des valeursd’exactitude et de spécificité ≥ 90%. Des valeurs de sensibilité et de précision ≥ 80% ont été observées pour tousles modèles discriminants concernant la proportion du pâturage dans la ration. Les modèles discriminants pour laproportion de pâturage + foin ≥ 72%, herbe totale (fraiche et conservée) ≥ 50%, le pâturage + foin ≥ 25%, absenced’herbe fermentée, absence d’ensilage de maïs et ensilage de maïs ≤ 30% dans la ration ont montré des valeursd’exactitude ≥ 80%, mais pour ces modèles soit la sensibilité, soit la précision ont été moins performantes. Lesmodèles construits pour tester le respect de l’ensemble des critères des cahiers des charges de chaque AOP ontmontré des valeurs d’exactitude, spécificité, sensibilité et précision > 90%. Les modèles pour la prédiction du %des aliments dans la ration tout comme les modèles discriminants peuvent permettre de fournir, via la MIR, desindicateurs sur la composition de la ration des troupeaux laitiers utiles aux éleveurs, filières et aux consommateurs.

International audience; The sharing of total environmental impacts between the dif- ferent products of a multi-output system is crucial in Life Cy- cle Assessment. ISO standards recommend subdivision then substitution methods when possible. Sometimes, allocations rules are necessary. They consist of allocating the total im- pact to the different products in proportion to a value that characterize the products. They can be based on physical pa- rameters (such as mass, protein, dry matter, etc.) or the eco- nomic value of coproducts can be used as a proxy. As they are based on various type of parameters, allocation rules can lead to significantly different environmental impact results. Then a consensus is difficult to reach between stakeholders as for example in meat sector. To make the debate going fur- ther, Chen et al. (2017) proposed a new allocation method based on biophysical parameters (Chen et al., 2017). Adapted from previous methods, they propose to allocate impacts in proportion to the energy needed for the growth, the mainte- nance and the activity of each tissue. The method has been judged as scientifically viable but also particularly difficult to apply due to the amount of necessary data and to the com- plexity of the calculation model. In a recent project, we developed a freeware to easily calculate biophysical allocation factors as well as mass and economic factors to allow a fair comparison: MeatPartTool. We also collected data to create a dataset of mass, economic and biophysical allocation factors for a large range of beef (132 individuals), calf (54 individ- uals) and lamb (14 individuals) at the slaughterhouse stage. This data paper provides both primary data and calculated allocation factors.

Background Goats were domesticated 10,500 years ago to supply humans with useful resources. Since then, specialized breeds that are adapted to their local environment have been developed and display specific genetic profiles. The VarGoats project is a 1000 genomes resequencing program designed to cover the genetic diversity of the Capra genus. In this study, our main objective was to assess the use of sequence data to detect genomic regions associated with traits of interest in French Alpine and Saanen breeds. Results Direct imputation from the GoatSNP50 BeadChip genotypes to sequence level was investigated in these breeds using FImpute and different reference panels: within-breed, all Capra hircus sequenced individuals, European goats and French mainland goats. The best results were obtained with the French goat panel with allele and genotype concordance rates reaching 0.86 and 0.75 in the Alpine and 0.86 and 0.73 in the Saanen breed respectively. Mean correlations tended to be low in both breeds due to the high proportion of variants with low frequencies. For association analysis, imputation was performed using FImpute for 1129 French Alpine and Saanen males using within-breed and French panels on 23,338,436 filtered variants. The association results of both imputation scenarios were then compared. In Saanen goats, a large region on chromosome 19 was significantly linked to semen volume and milk yield in both scenarios. Significant variants for milk yield were annotated for 91 genes on chromosome 19 in Saanen goats. For semen volume, the annotated genes include YBOX2 which is related to azoospermia or oligospermia in other species. New signals for milk yield were detected on chromosome 2 in Alpine goats and on chromosome 5 in Saanen goats when using a multi-breed panel. Conclusion Even with very small reference populations, an acceptable imputation quality can be achieved in French dairy goats. GWAS on imputed sequences confirmed the existence of QTLs and identified new regions of interest in dairy goats. Adding identified candidates to a genotyping array and sequencing more individuals might corroborate the involvement of identified regions while removing potential imputation errors.

Multiblock PLS-DA on fecal and plasma visible-near-infrared spectra for discriminating young bulls according to their efficiency. Preliminary results. Conférence Chimiométrie 2020

International audience

International audience; There is scarce information on whether inhibition of rumen methanogenesis induces metabolic changes on the host ruminant. Understanding these possible changes is important for the acceptance of methane-reducing practices by producers. In this study we explored the changes in plasma profiles associated with the reduction of methane emissions. Plasma samples were collected from lactating primiparous Holstein cows fed the same diet with (Treated, n = 12) or without (Control, n = 13) an anti-methanogenic feed additive for six weeks. Daily methane emissions (CH4, g/d) were reduced by 23% in the Treated group with no changes in milk production, feed intake, body weight, and biochemical indicators of health status. Plasma metabolome analyses were performed using untargeted [nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC–MS)] and targeted (LC–MS/MS) approaches. We identified 48 discriminant metabolites. Some metabolites mainly of microbial origin such as dimethylsulfone, formic acid and metabolites containing methylated groups like stachydrine, can be related to rumen methanogenesis and can potentially be used as markers. The other discriminant metabolites are produced by the host or have a mixed microbial-host origin. These metabolites, which increased in treated cows, belong to general pathways of amino acids and energy metabolism suggesting a systemic non-negative effect on the animal.

The establishment of cooperations favouring crop-livestock interactions on the scale of several farmsappears to be an alternative that optimises the use and preservation of resources on a territory and makes itpossible to reduce many biogeochemical and economic imbalances. Setting up a short alfalfa hay production chaincould improve soil fertility, reduce inputs and risks for cereal farmers and promote local protein supply for livestockfarmers, but there is a lack of reference and framework to facilitate and support the implementation of such croplivestock cooperation approaches. The objective of this study was to estimate the interest price of alfalfa hay,respectively for a potentially producing crop farm and dairy cattle farms likely to purchase alfalfa hay. To do this, weused the ORFEE bio-economic optimization model. Three typical farms were modelled: one farm specialising incrops on the plain and two dairy cattle farms. The first is a piedmont grassland system with standard milkproduction. The second is a system with cheese production and processing under PGI Tomme and Emmental.These three production systems have been optimised according to three scenarios: 1) without alfalfa hay (control),2) possibility of producing or purchasing alfalfa hay, without quantity commitment but with prices fluctuatingaccording to the price of the fodder, 3) possibility of producing or purchasing alfalfa hay, with quantity commitmentover 3 years and guaranteed price. We estimated the interest price of alfalfa hay: the price at which the farmerderives at least as much "utility" from producing or purchasing alfalfa as from not producing or purchasing alfalfa.We established for alfalfa hay a selling price range between 145 and 151 €/t and a buying price range of 179 to181 €/t for standard milk production and 201 to 206 €/t for PGI production. This first result shows that farmers(stockbreeders and cereal farmers) can find an economic interest in this exchange, even if it remains moderate.This study also showed a significant difference in the interest price for the two livestock farms, highlighting a betterpropensity to pay for livestock farming with PGI cheese production. In addition to this first economic criterion, thereis a real interest in the traceability of the fodder purchased, as well as in the image of local production., La mise en place de coopérations favorisant les interactions culture-élevage à l'échelle de plusieursexploitations agricoles apparaissent comme une alternative optimisant l'utilisation et la préservation des ressourcessur un territoire et permettent de réduire de nombreux déséquilibres biogéochimiques et économiques. La mise enplace d'une filière courte de foin de luzerne, pourrait permettre d'améliorer la fertilité des sols, réduire les intrants etles risques pour les céréaliers et favoriser un approvisionnement protéique local pour les éleveurs, mais il existe unmanque de référence et de cadrage pour faciliter et accompagner la mise en place de telles démarches decoopération culture-élevage. L'objectif de cette étude était de faire une estimation du prix d'intérêt du foin deluzerne, respectivement pour une exploitation céréalière potentiellement productrice, et des exploitations bovin laitsusceptibles d'acheter du foin de luzerne. Pour cela, nous avons utilisé le modèle d'optimisation bioéconomiqueORFEE. Trois exploitations types ont été modélisées : une exploitation spécialisée en grandes-cultures en plaineet deux exploitations en élevage bovins laitiers. La première est un système herbager de piedmont avec uneproduction en lait standard. La seconde est un système avec production et transformation fromagère sous IGPTomme et Emmental. Ces trois systèmes de productions ont été optimisés selon trois scénarios : 1) sans foin deluzerne (témoin), 2) possibilité de produire ou d'acheter du foin de luzerne, sans engagement de quantité maisavec des prix fluctuant selon le cours des fourrages, 3) possibilité de produire ou d'acheter du foin de luzerne, avecengagement de la quantité sur 3 ans et prix garanti. Nous avons estimé les prix d'intérêt du foin de luzerne : prix àpartir duquel l'agriculteur retire au moins autant « d'utilité » à produire ou acheter de la luzerne qu'à ne pas le faire.Nous avons pu établir pour du foin de luzerne une fourchette de prix de vente entre 145 et 151 €/t et une fourchettede prix d’achat de 179 à 181€/t pour l'élevage en lait standard et de 201 à 206€/t pour l’élevage avec IGP. Cepremier résultat montre que les agriculteurs (éleveurs et céréaliers) peuvent trouver un intérêt économique danscet échange, même si celui-ci reste modéré. Cette étude a également montré un écart important dans le prixd'intérêt pour les deux exploitations d'élevage, mettant en évidence une meilleure propension à payer pourl'élevage avec une production fromagère sous IGP. S'ajoute à ce premier critère économique un réel intérêt sur latraçabilité du fourrage acheté, ainsi que sur l'image d'une production locale.

Cheap and rapid methods to predict between-animal variability of feed efficiency (FE) are needed. We evaluated, by using a large dataset on beef cattle (n = 355) fed contrasting diets (grass vs corn based diets), the potential of plasma natural 15N abundance (δ15N) as a biomarker of between-animal variation in FE, measured either as feed conversion efficiency (FCE) or residual feed intake (RFI). Data were analyzed by mixed models, with diet and δ15N as a fixed effect and experimental farm, batch and pen as random effects. A negative and significant correlation was found between FCE and δ15N within each contemporary group, with a lower response (slope) however in grass vs corn diets (δ15N × diet interaction; P = 0.002). Likewise, we found a significant but positive relationship between δ15N and RFI, but without the influence of diet or any tested random effect. Our results indicate that δ15N is a promising biomarker of between-animal variation of feed efficiency (FCE and RFI) in growing beef cattle.

This review is aimed at providing an overview of recent advances made in the field of meat quality prediction, particularly in Europe. The different methods used in research labs or by the production sectors for the development of equations and tools based on different types of biological (genomic or phenotypic) or physical (spectroscopy) markers are discussed. Through the various examples, it appears that although biological markers have been identified, quality parameters go through a complex determinism process. This makes the development of generic molecular tests even more difficult. However, in recent years, progress in the development of predictive tools has benefited from technological breakthroughs in genomics, proteomics, and metabolomics. Concerning spectroscopy, the most significant progress was achieved using near-infrared spectroscopy (NIRS) to predict the composition and nutritional value of meats. However, predicting the functional properties of meats using this method—mainly, the sensorial quality—is more difficult. Finally, the example of the MSA (Meat Standards Australia) phenotypic model, which predicts the eating quality of beef based on a combination of upstream and downstream data, is described. Its benefit for the beef industry has been extensively demonstrated in Australia, and its generic performance has already been proven in several countries.

The development of 3D imaging is a solution for estimating morphological parameters and growth development in dairy cattle but it also offers opportunities to estimate original indicators such as volume, body surface area and body weight. The objective of the Morpho3D project was to develop, test and validate a device offering the possibility to record and analyze complete 3D shapes of dairy cattle. To evaluate the performance of this tool, two trials were carried out on Holstein cows, one in 2017 on 30 cows and one in 2018 on 64 cows. The precision of linear measurements (height at the withers (HG), chest circumference (TP), chest depth (PP), hip width (LH), backside width (LF) and ischial width (LI)), volume and body surface area were first tested on inert forms (plastic cow and cylinder). The differences observed between manual reference measurements and estimates on the 3D image were less than 1% for area and volume and ranged from 1.3% to 11.2 % for linear measurements. For the repeatability and reproducibility of the method for estimating volume and area in living animals, the coefficients of variation (CVs) were 0.17 and 3.12 % respectively. For linear measurements, the CVs ranged from 0.26 to 9.81 % for repeatability and from 0.94 to 7.34 % for reproducibility. Four models for estimating the liveweight of cows were established. The coefficients of determination ranged from 0.82 to 0.93 % with weight prediction errors around 3 % (20 kg) as function of the volume and 4 % (29 kg) using the area. The device and the method, evaluated and validated in the present study, offer possibilities of using new indicators such as volume and body surface in precision breeding.; Le développement de l'imagerie 3D est une solution pour estimer des paramètres morphologiques et le développement de la croissance des vaches laitières, mais il offre également des opportunités pour estimer des indicateurs originaux tels que le volume, la surface corporelle et le poids vif. L’objectif du projet Morpho3D était de développer, tester et valider un dispositif offrant la possibilité d'enregistrer et d'analyser des formes 3D complètes de bovins laitiers. Pour évaluer les performances de cet outil, deux essais sur vaches de race Holstein ont été menés, l’un sur 30 vaches en 2017 et l’autre sur 64 animaux en 2018. La précision des mesures linéaires (hauteur au garrot (HG), tour de poitrine (TP), profondeur de poitrine (PP), largeur des hanches (LH), largeur des fesses (LF) et largeur des ischions (LI)), du volume et de la surface corporelle a d'abord été testée sur des formes inertes (vache en plastique et cylindre). Les différences observées entre les mesures de référence manuelles et les estimations sur images 3D étaient inférieures à 1 % pour la surface et le volume et allaient de 1,3 % à 11,2 % pour les mensurations linéaires. Pour la répétabilité et la reproductibilité de la méthode d’estimation du volume et de la surface sur des animaux vivants, les coefficients de variations (CV) étaient de 0,17 et 3,12 % respectivement. Pour les mensurations linéaires, les CV variaient de 0,26 à 9,81 % pour la répétabilité et de 0,94 à 7,34 % pour la reproductibilité. Quatre modèles d'estimation du poids vif des vaches ont été établis. Les coefficients de détermination variaient de 0,82 à 0,93 % avec des erreurs de prédiction du poids de l'ordre de 3 % (20 kg) en utilisant le volume dans le modèle et 4 % (29 kg) en utilisant la surface. Le dispositif et la méthode, évalués et validés dans la présente étude, offrent des possibilités d'utilisation de nouveaux indicateurs tels que le volume et la surface corporelle en élevage de précision.

The context of milk production is changing in France. The operations are expanding and specializing, support tothe farmers must evolve. During 2017, dairy farmers and advisors were brought together in focus groups to reflectand discuss the support needs in these dairy farms, as they felt they were for themselves, in the case of farmers, or among the farmers they work with in their activity for the advisors. Farmers in dairy farms were selected on specific criteria: more than 100 cows, more than 3 persons in the workforce or with a high productivity per labour unit (more than 500,000 litres per labour unit). Two focus groups of farmers took place, 12 farmers in Western France and 14 in Eastern France. The focus group of advisors took place in Brittany with 18 advisors from various trades and structures (banks, veterinarians, milk recording, food, chambers of agriculture, strategy consulting, National Social Insurance for agricultural workers, …). The farmers and advisors gathered expressed their strong interest of this purpose for these dairy farms. Farmers identify specificities in the management of large dairy herds ‘an essential organization of work, more time spent in the office than in the stable, business management and the management at herd-scale and not per cow’. Western farmers have highlighted their need for support around the management of human relations, and in particular communication within the work collective, while Eastern farmers testify to needs on employee management (training, sustainability of the workforce, labour legislation,...) and how to adapt their farm to a changing context (market uncertainties). The advisors insisted on the need to develop long-term support measures (preventive rather than curative actions), whose added value is sometimes difficult to have recognized and sold to farmers. They insist on the need to acquire specific references on large herds, as well as on the sharing of various data between advisors in order to design an approach adapted to each farm.

Energy deficiency (ED) is known to have many origins on farms (beginning of lactation, climatic conditions…)and to impact dairy cows’ performances. If some indicators regarding ED have been highlighted in the past, theiron-farm use remains unclear and possible use of other indicators or demands on new expectations from both farmers and stakeholders are unknown. Students involved in animal sciences at Agrocampus Ouest (France) led two semi-quantitative surveys in order to collect such information. Stakeholders (vets, specialists in nutrition…; n=14) were exclusively selected from existing network, while farmers (n=67) were selected either from existing networks (n=32) or randomly (n=35). Farmers’ surveys were completed by phone (n=42) or on-farm (n=25). The surveyed holdings were 33 to 320-ha wide, organic (n=13) or not and mainly from western part of France (n=52), the most significant area of dairy farms in the country. 8/67 of farmers were unable to define ED but all knew how to handle this problem when occurring. For both stakeholders and farmers, the sensitive periods were early lactation (33/81) and summer season (32/81). Farmers also included dietary transitions in the sensitive periods (22/67). Almost half of them regularly experienced energy deficiency on their farm (38/67). The most-cited indicator was the change in milk composition (64% of both stakeholders and farmers); the second was body condition score (BCS) (31% of them). Farmers seem to rely more on visual indicators, such as BCS (44/67), coat appearance (7/67) and lameness (4/67), whereas stakeholders prefer to use technical indicators, such as protein (11/14) and fat (4/14) content of milk. Most of them don’t need any additional indicator or tool to follow the energy deficiency (33/81) but they would appreciate to have a more sensitive daily indicator (18/81).

International audience; Within the framework of the Horizon 2020 thematic network Inno4Grass (www.inno4grass.eu), 55 ‘practice & science meetings’ have been carried out using a multi-stakeholder, participatory approach, in order to bridge the gap between science and practice and deliver a comprehensive analysis of grassland innovations across eight European countries. Three project phases can be distinguished: (1) common guidelines under discussion, (2) introduction and preliminary test of the guidelines, (3) additional training on the discussion process. A structured feedback on the meetings held was provided by the organisers by means of a questionnaire, including information about duration, preparatory material, participants, discussion methods and evaluation of the meetings by the organisers. This information allows computing of mean values and distribution of the most relevant variables. Only a few of them were affected by the project phase. In particular, there was an increase in the use of farm portraits and of scientific literature over the project phases. All aspects describing the success of meetings were positively assessed. This suggests that the methodology for the conduction of the practice & science meetings within Inno4Grass was already relatively well established at the beginning of the project.

Milk safety and quality are critical issues for human health and welfare. MILKQUA is a PRIMA* cross-multidisciplinary project engaging five EU partners from four countries (France, Italy, Spain, and Portugal) that will team with five Tunisian partners representing research, development, extension and farmers. It aims at enhancing milk and dairy food quality and safety, and decreasing milk-associated health hazards, by reducing the use of conventional antimicrobial products in Tunisian farms to align with the concept of One Health approach. The main objectives of this project are the following: 1- to set up an extension-based national milk program (QMP) to reduce the incidence of mastitis, and the consequent use of antibiotics in Tunisia, 2- to explore the potential use of essential oils and plant extracts with antibacterial activities in diets of dairy cattle to decrease the burden of mastitis, and to increase feed efficiency, and to improve animal welfare and the sustainability of milk production system, and 3- to improve milk quality including the shelf life of dairy products. The project will strongly rely on up-to-date system biology (both in vitro and in vivo assays) and OMICs methodologies. MILKQUA ambition is to enhance the role of Tunisian dairy producers as providers of sustainable food supply to consumers. It will also intend to lay the foundation of an accountable and dynamic system that will stimulate the economy growth and promote prosperous and resilient communities across the country and elsewhere, providing new knowledge about the biological effects of natural compounds that will be extended to other Mediterranean countries. * Partnership on Research and Innovation in the Mediterranean Area (PRIMA) partly funded by EU's research and innovation program Horizon 2020

For several years, studies conducted for discovering tenderness biomarkers have proposed a list of 20 candidates. The aim of the present work was to develop an innovative methodology to select the most predictive among this list. The relative abundance of the proteins was evaluated on five muscles of 10 Holstein cows: gluteobiceps, semimembranosus, semitendinosus, Triceps brachii and Vastus lateralis. To select the most predictive biomarkers, a multi-block model was used: The Data-Driven Sparse Partial Least Square. Semimembranosus and vastus lateralis muscles tenderness could be well predicted (R&sup2, = 0.95 and 0.94 respectively) with a total of 7 out of the 5 times 20 biomarkers analyzed. An original result is that the predictive proteins were the same for these two muscles: &micro, calpain, m-calpain, h2afx and Hsp40 measured in m. gluteobiceps and &micro, calpain, m-calpain and Hsp70-8 measured in m. Triceps brachii. Thus, this method is well adapted to this set of data, making it possible to propose robust candidate biomarkers of tenderness that need to be validated on a larger population.

International audience; Managing infections of sheep with anthelmintic resistant gastrointestinal nematodes (GIN) is a major challenge for sheep producers in Western Europe. New methods of grazing management have been poorly explored as a component of an integrated and sustainable control of these parasites. Therefore, the purpose of this study was to evaluate the effect of two different types of grazing systems of sheep (intensive cell grazing versus conventional rotational grazing) on GIN infections over two years in a farm located in a temperate environment of Western France. When considering the whole study, the type of grazing system did not influence significantly the intensity of egg excretions of adult ewes even if the proportion of ewes excreting high numbers of GIN eggs was higher in cell grazing system than in rotational grazing system. The most striking result of this survey was the effect of grazing system on the GIN species composition harbored by ewes and by their lambs: with time, the proportions of H. contortus infections were lower in cell grazing system than in rotational grazing system. In conclusion, the cell grazing system, as implemented in this study, could limit the importance of this highly pathogenic nematode species in sheep.

There is a need to quantify methane (CH4) emissions with alternative methods. For the past decade, milk fatty acids (MFA) could be used as proxies to predict CH4 emissions from dairy cows because of potential common rumen biochemical pathways. However, equations have been developed based on a narrow range of diets and with limited data. The objectives of this study were to (1) construct a set of empirical models based on individual data of CH4 emissions and MFA from a large number of lactating dairy cows fed a wide range of diets; (2) further increase the models' level of complexity (from farm to research level) with additional independent variables such as dietary chemical composition (organic matter, neutral detergent fiber, crude protein, starch, and ether extract), dairy performance (milk yield and composition), and animal characteristics (days in milk or body weight); and (3) evaluate the performance of the developed models on independent data sets including measurements from individual animals or average measurements of groups of animals. Prediction equations based only on MFA [C10:0, iso C17:0 + trans-9 C16:1,cis-11 C18:1, and trans-11,cis-15 C18:2 for CH4 production (g/d); iso C16:0, cis-11 C18:1, trans-10 C18:1, and cis-9,cis-12 C18:2 for CH4 yield (g/kg of dry matter intake, DMI); and iso C16:0, cis-15 C18:1, and trans-10 + trans-11 C18:1 for CH4 intensity (g/kg of milk)] had a root mean squared error of 65.1 g/d, 2.8 g/kg of DMI, and 2.9 g/kg of milk, respectively, whereas complex equations that additionally used DMI, dietary neutral detergent fiber, ether extract, days in milk, and body weight had a lower root mean squared error of 46.6 g/d, 2.6 g/kg of DMI, and 2.7 g/kg of milk, respectively). External evaluation with individual or mean data not used for equation development led to variable results. When evaluations were performed using individual cow data from an external data set, accurate predictions of CH4 production (g/d) were obtained using simple equations based on MFA. Better performance was observed on external evaluation with individual data for the simple equation of CH4 production (g/d, based on MFA), whereas better performance was observed on external evaluation mean data for the simple equation of CH4 yield (g/kg of DMI). The performance of evaluation of the models is dependent on the domain of validity of the evaluation data sets used (individual or mean).

International audience; Dairy systems are a source of pollutant emissions, such as greenhouse gases (GHG) and NH3 that are associated with impacts on the environment. Gas emissions in barns are related mainly to diet intake and chemical composition, N excretion and manure management. A reduction in dietary N is known to be an effective way to reduce N excretion and the resulting NH3 emissions. However, most studies consider manure in liquid form with frequent removal from the barn. In deep litter systems, several processes can occur during the accumulation of solid manure that result in variable gas emissions. The objective of this experiment was to investigate the influence of the interaction between dietary CP (low or high) and manure management (liquid or solid) on gas emissions (NH3, N2O, CH4) at the barn level. Dietary treatments provided either low (LowN; 12% CP) or high (HighN; 18% CP) degradable protein to modify the amount of total ammonia nitrogen (TAN) excreted. The cows were housed for two 8-week periods in two mechanically ventilated rooms equipped to manage manure either in liquid (LM; slurry) or solid form (SM; deep litter). In the LM treatment, N balance was measured for 4 days. As expected, animals fed the LowN diet ingested 35% less N and excreted 65% less N in their urine, with no reduction in faecal N excretion and N secretion in milk. On the LowN diet, excretion of urea-N and NH3-N emissions were reduced regardless of the manure management. On the HighN diet, urinary urea-N excretion was three times as high, while NH3-N emissions were 3.0 and 4.5 times as high in LM and SM, respectively. Manure management strongly influenced CH4-C emissions, which were 30% higher in SM than in LM, due to the accumulation of litter. Moreover, gas emissions from solid manure increased over the accumulation period, except for NH3 on the LowN diet. Finally, our results suggest that methods used for national inventories would become more accurate by considering the variability in TAN excretion, which is the primary factor that influences NH3 emissions.

Preprint recommended by the Peer Community In Animal Science (https://animsci.peercommunityin.org/).It can be cited as followed: Le Cozler Y., Jurquet J., and Bedere N. (2019). Effects of feeding treatment on growth rate and performance of primiparous Holstein dairy heifers. bioRxiv, 760082 ver. 3 peer-reviewed and recommended by PCI Animal Science. DOI: 10.1101/760082; International audience; The objective of this study was to investigate effects of feeding-rearing programs that aim for first calving at 20-27 months (mo) of age on growth, reproduction and production performance of Holstein cows at nulliparous and primiparous stages. We hypothesised that, in a seasonal autumn-calving strategy, heifers born late in the season could catch up to the growth of heifers born earlier and be inseminated during the same period, at a body weight (BW) of at least 370 kg. This approach would result in first calving age at 21-22 mo of age without impairing their later performance. To test this hypothesis, we studied 217 heifers over 3 years. They were split into three treatment groups: control feeding (SD), an intensive-plane diet (ID1) from birth to 6 mo of age or an intensive-plane diet from birth to one year of age. Heifers in groups SD and ID1 were born from September until the end of November, while those in ID2 were born later. The present study showed that late- born heifers (ID2) could catch up with the growth of the others due to the feeding treatment, although they were still 42 kg lighter than the SD and ID1 heifers at first calving. No difference in reproductive performance was observed among groups. Once primiparous, the cows reared with the ID2 treatment tended to produce less milk than SD and ID1 cows (ca. 400 kg less on a 305 d basis throughout lactation), and no differences in milk composition, feed intake, body condition score or BW were observed among groups.Age at first service (AFS) was classified a posteriori into three classes: 12.5 (AFS12.5), 14.0 (AFS14.0) and 15.5 mo (AFS15.5) of age. Heifers in AFS12.5 grew faster than those in AFS14.0 and AFS15.5. Once primiparous, the AFS12.5 cows tended to produce less milk at peak than AFS14.0 and AFS15.5 cows (ca. 1.5 kg/d less) although no difference in total milk yield during lactation was observed. No differences in milk composition, feed intake, body condition score or BW were observed among groups. These results support the conclusion that the feeding treatment can enable late-born heifers to catch upto the growth of heifers born earlier in the season. This strategy results in an earlier first calving that does not impair their reproductive performance but does decrease milk yield slightly during first lactation. Future studies should investigate long-term effects of this strategy.

International audience; Monitoring the growth and body condition of cows is essential for optimal management of modern dairy farms. However, monitoring is rarely performed on commercial farms. Modern technologies based on three-dimensional (3D) shape analysis could address this problem. The objective of the present study was to test and validate tools that can record and analyze 3D body shapes of animals. On 30 Holstein dairy cows, wither height (WH), heart girth (HG), chest depth (CD), hip width (HW), backside width (BaW) and ischial width (IW) were manually measured. These manual measurements were compared to those measured with a scanner (Morpho3D) that provided 3D images of the entire cow body. Correlations between manual and Morpho3D measurements were high: 0.89 for CD, 0.82 for HW, 0.78 for HG, 0.76 for BaW, 0.63 for IW and 0.62 for WH. The mean coefficient of variation of reproducibility for Morpho3D was 2.8%. Future development can provide new opportunities for dairy herd management based on determining animal body volume and surface area.

Complete nitrogen balance in dairy cows: does every drop of sweat count?. 10. International Symposium on the Nutrition of Herbivores (ISNH)

Lipolysis is an enzymatic reaction which leads to off-flavour in milk and impairs technological properties of milk. Lipolysis corresponds to the hydrolysis of milk fat located in milk fat globules (MFG) by the lipoprotein lipase (LPL) and its cofactors, leading to free fatty acid accumulation. Variability of spontaneous lipolysis (SL) levels depend on individuals and on breeding systems. Five trials were set up to understand SL variations. The effect of breed, parity, physiological stage, milking frequency, milking time, feeding systems and lipid supplementation on SL were evaluated by continuous designs. The effects of milking time, feeding restriction and nature of forage on all enzymatic system were evaluated by two cross-over studies. Data were analysed using linear models. Cows from the five trials could be classified in two groups according to their phenotype: ‘susceptible’ and ‘non-susceptible’ to SL, confirming the strong impact of the individual effect. Among ‘susceptible’ cows, we confirmed the effects of breed, parity, physiological stage, milking time, milking frequency and feeding systems. SL was higher in Holstein cows’ milk than in Normande cows’ milk (P

International audience; This article shows how new theoretical work on assessing sustainability of farms, carried out as part of a multidisciplinary approach, allowed a new theoretical framework to be develop, along with version 4 of the IDEA Method (Indicateurs de Durabilité d'une Exploitation Agricole). The first section divides existing studies taken from the literature into two types of indicator-based conceptual frameworks: those based on sustainable agriculture objectives, and those based on a systemic approach focusing on the properties of sustainability as applied to agriculture. The second part of this article explains the overall process of assessing farm sustainability based on the conceptual framework developed for IDEA v.4. The theoretical framework relates to strong sustainability, and agricultural multifunctionality (with 12 associated objectives). The method includes a systemic analysis of sustainability based on five properties observed within a sustainable farm: The ability to produce and reproduce goods and services; Autonomy; Robustness, Territorial embeddedness and Overall responsibility. These properties are then evaluated from 54 different indicators of agricultural sustainability. The method combines two mutually complementary approaches to assessing sustainability. The first of these examines the extent to which sustainability has been achieved (in agro-ecological, socio-territorial and economic terms) by aggregating indicators based on 13 components and a scoring system using sustainability " units ". The second approach assesses the level of sustainability based on the five properties mentioned above. Indicators are aggregated hierarchically and organised based on 14 key categories. We show how the concept of properties has real educational value and can help to bring a new perspective to the field of sustainable farming.

Total protein conversion efficiency of ruminant production systems is low (between 0.05 for meat and 0.25 for milk), but this calculation usually does not differentiate human-edible from human non-edible feedstuffs (e.g. grass, by-products of food and biofuels industries). To evaluate the net contribution of ruminant livestock to protein production for human consumption in France we estimated the humanedible protein Fraction (hepF) of the diets and the net protein efficiency (human-edible protein efficiency) from six contrasting feeding systems in dairy, beef cattle and sheep systems. The hepF values of diets ranged from 3% (extensive sheep production) up to 26% (intensive dairy cattle production). The net protein efficiency ranged from 0.34 (intensive sheep production) up to 2.57 for grass-based dairy cattle production with low concentrate consumption. Each type of ruminant production can produce more edible protein than they consume (net protein efficiency > 1). The use of grass and by-products are the key factors to improve the net contribution of ruminant production to protein supply for humans.

Environmental and economic performances of livestock production are related largely to the production of complete feeds provided on commercial farms. Formulating feeds based on environmental and economic criteria appears a suitable approach to address the current challenges of animal production. We developed a multiobjective (MO) method of formulating feed which considers both the cost and environmental impacts (estimated via life cycle assessment) of the feed mix. In the first step, least-cost formulation provides a baseline for feed cost and potential impacts per kg of feed. In the second, the minimised MO function includes normalised values of feed cost and impacts climate change, P demand, non-renewable energy demand and land occupation. An additional factor weights the relative influence of economic and environmental objectives. The potential of the method was evaluated using two scenarios of feed formulation for pig, broiler and young bulls. Compared to baseline feeds, MO-formulated feeds had lower environmental impacts in both scenarios studied (−2 to −48 %), except for land occupation of broiler feeds, and a moderately higher cost (1–7 %). The ultimate potential for this method to mitigate environmental impacts is probably lower than this, as animal supply chains may compete for the same low-impact feed ingredients. The method developed complements other strategies, and optimising the entire animal production system should be explored in the future to substantially decrease the associated impacts.

The Meat Standards Australia (MSA) grading scheme has the ability to predict beef eating quality for each ‘cut×cooking method combination’ from animal and carcass traits such as sex, age, breed, marbling, hot carcass weight and fatness, ageing time, etc. Following MSA testing protocols, a total of 22 different muscles, cooked by four different cooking methods and to three different degrees of doneness, were tasted by over 19 000 consumers from Northern Ireland, Poland, Ireland, France and Australia. Consumers scored the sensory characteristics (tenderness, flavor liking, juiciness and overall liking) and then allocated samples to one of four quality grades: unsatisfactory, good-every-day, better-than-every-day and premium. We observed that 26% of the beef was unsatisfactory. As previously reported, 68% of samples were allocated to the correct quality grades using the MSA grading scheme. Furthermore, only 7% of the beef unsatisfactory to consumers was misclassified as acceptable. Overall, we concluded that an MSA-like grading scheme could be used to predict beef eating quality and hence underpin commercial brands or labels in a number of European countries, and possibly the whole of Europe. In addition, such an eating quality guarantee system may allow the implementation of an MSA genetic index to improve eating quality through genetics as well as through management. Finally, such an eating quality guarantee system is likely to generate economic benefits to be shared along the beef supply chain from farmers to retailors, as consumers are willing to pay more for a better quality product.

Take home message When accurate high throughput monitoring and a steady environment are used, the variability of residual feed intake is only 8% of the variability of energy intake in Holstein cows over a full lactation. Even in these experimental conditions, only 59% out of these 8% are really associated with feed efficiency differences and not with errors. Introduction Reducing the use of resources to maintain production and decrease dairy cow impact on the environment is a major challenge to tackle and is known as improving feed efficiency. Feed efficiency is often estimated with the residual intake defined as the difference between the actual feed intake and the feed intake predicted from the energy consumed or produced by the major biological functions (lactation, body reserves gain and loss and maintenance) (Berry and Crowley, 2013). As residuals of a statistical model, residual intake does not only include feed efficiency differences, but also the accumulated errors of model fitting and errors of measurement. Aggrey and Rekaya (2013) in broilers and Savietto et al., (2014) in beef cattle used a mixed model with random animal effect to isolate the REI only associated with animal feed efficiency differences and not with errors. The objective of the present study was to estimate the part of residual intake variability in dairy cows really associated with feed efficiency differences and less with errors, thanks to a mixed model with random animal effect (Fischer et al., 2017). Material & methods Holstein cows were housed in a free-stall barn and fed with a single TMR based on corn silage and concentrates during the whole lactation. One hundred and nineteen cows were monitored throughout the first 238 days in milk for daily individual feed intake as the difference between offered dry matter and next morning refusals dry matter. All cows were also monitored for morning body weight after milking, daily milk yield, twice a week daily milk protein, fat and lactose, and monthly body condition score with a 0.25 increment scale going from 0 for an emaciated cow to 5 for a fat cow. Feed efficiency was estimated as the residual energy intake (REI): the residual of the linear regression of average net energy intake on average net energy in milk, average metabolic body weight and body condition score gain and loss, both multiplied by average body weight. To estimate the REI associated with feed efficiency and not with errors, the variables used to estimate REI - milk yield and composition, body condition score change, feed intake and body weight - were averaged per 2 week period to create repeated measures per cow during the 238 monitored days. A mixed model was then fitted with random cow-specific slopes for the variables and a random cow-specific intercept. The difference between the energy intake predicted with the cow-specific regression slopes and intercept and the energy intake predicted with the population average slopes and intercept was interpreted as animal variability in feed efficiency and not the error. Results & discussion The variability of REI represented 8% of the variability of the actual net energy intake among the 119 Holstein cows over near the whole lactation. Of this 8% of REI variability, the cow-specific part isolated with the mixed model was only 59%. By definition, this 59% of REI variability is repeatable throughout time and associated with cows, and thus could be considered as feed efficiency differences. However, certain types of errors can be repeatable throughout time and associated with cows, such as sorting feed. The remaining 41% is by definition not repeatably specific to cows throughout time and therefore most probably associated with model fitting errors or measurement errors. However, when temporary events such as clinical mastitis, only affect intake or only affect a biological function, then it is cow-specific, but is not repeatable throughout time and will be included in the error of the mixed model and thus not considered as feed efficiency. Conclusion When using high throughput monitoring of individual feed intake and of the major energy consuming functions in dairy cows fed with a single high energy diet during the whole lactation, residual energy intake differences among Holstein cows are only 8% of the total variability of feed intake. Thanks to a mixed model with cow-specific regression slopes and intercept, we were able to identify that of this 8%, only 59% may be associated with feed efficiency differences and not with model fitting errors or measurement errors.

Among techniques for estimating enteric methane (CH(4)) emission by ruminants, open-circuit respiration chambers (OC), the use of a gas tracer (SF(6)), and the GreenFeed (GF) device are the most commonly used. In this study, we compared these techniques in 8 dry cows receiving a diet made of 70% hay and 30% concentrates given in limited and constant amounts, in a 15-wk experiment. Two periods in free stalls for SF(6) and GF and in chambers for OC were used; in addition, SF(6) was determined in chambers for 1 period. Methane emission (g/d) and CH(4) yield (g/kg DMI) were higher (P < 0.0001) for OC than for SF(6) and GF (367, 310, and 319 g/d for OC, SF(6), and GF, respectively). The difference between OC and GF was related to a difference in post-prandial rate of gas emission. The between-animal coefficient of variation of CH(4) emission was higher for SF(6) than for OC and GF (20.8, 13.5, and 12.0% on average, respectively). Correlation coefficients between OC and SF(6) were high and significant for CH(4) emission and CH(4) yield (r = 0.782 and r = 0.717, respectively; P < 0.05), but not significant between OC and GF, or between SF(6) and GF. Correlation coefficients were highly significant for SF(6) determined either in free stalls or in chambers (r = 0.908 and 0.903 for CH(4) in g/d and g/kg DMI, respectively; P < 0.01). Carbon dioxide (CO(2)) emission and CO(2) yield were similar for GF and OC (10,003 and 9,887 g/d, 752 and 746 g/kg DMI, respectively); CO(2) data obtained with SF(6) were lower (7,718 g/d and 606 g/kg DMI; P < 0.0001), but this technique is not relevant for CO(2) emission determination. Correlation coefficients between OC and GF were not significant for CO(2) emission and CO(2) yield. This set of results shows that differences between methods are minor for average values, but that individual correlations may limit their interchangeability for determining gas emissions of individual animals. This study also shows the reliability of GF on-farm determination of CH(4) and CO(2) emissions for groups of animals.

International audience; Chez les petits ruminants, les outils d'intervention et corolairement de gestion en matière d'infections mammaires, doivent être repensés en tenant compte de leurs spécificités sur le plan animal (étiologie, réponse cellulaire, caractéristiques morphologiques et fonctionnelles) comme de conduite d'élevage, d'équipement ou d'organisation du travail. L'étude s'est attachée à intégrer les apports de l'observation en élevage, élément central du travail des éleveurs et des techniciens, et différentes solutions technologiques ou enregistrements automatisés, disponibles ou en développement, sur le plan diagnostique (bactériologie moléculaire, comptages cellulaires, spectres en moyen infra-rouge, examen clinique de la mamelle) et sur le plan de l'aptitude et des conditions de traite (recours aux enregistrements de cinétiques d'éjection du lait, de fluctuations de vide, de thermographie). Dans un contexte de réduction de l'usage des antibiotiques, des critères de sélection des animaux à traiter (ou réformer) ont été proposés. Des phénotypes ont été explorés en vue d'une meilleure appréhension des facteurs de risque associés à la traite. Enfin, après étude des caractères et simulations en termes de progrès génétique et d'impact économique, l'inclusion de nouveaux caractères dans les schémas de sélection a été réalisée (cellules) ou proposée en vue d'une amélioration de la résistance des animaux aux infections mammaires. Abstract: Toward innovative tools of intervention and decision aid to control mammary infections in small ruminants breeding In small ruminants, intervention and management tools for the control of mammary infections must be rethought, taking into account their specificities at the animal level (etiology, cellular response

Excessive negative energy balance (EB) has been associated with decreased reproductive performance and increased risk of lameness and metabolic diseases. On-farm, automated EB estimates for individual cows would enable dairy farmers to detect excessive negative EB early and act to minimize its extent and duration by altering feeding. Previously, we have shown that EB can be estimated from frequent measurements of body weight (BW) and body condition score (BCS) changes, referred to as EBbody. In this study, we investigated the robustness and sensitivity of the EBbody method to assess its genericity and on-farm applicability. We used 5 data sets with BW of lactating cows (name of data set in parenthesis): 65 Holstein cows in a French feeding trial (INRA); 6 Holstein cows in a British feeding trial (Friggens); 31 Holstein cows and 17 Jersey cows in a Danish feeding trial (DCRC); 140 Holstein cows in a British feeding trial (Scotland's Rural College, SRUC); and 1,592 Holstein cows on 9 Danish farms with milking robots (automatic milking system). We used the INRA and Friggens data sets to develop a dynamic formula to correct BW for increasing residual gut-fill (RGF) during early lactation. With the DCRC data, we tested the effect of smoothing parameters and weighing frequency on EBbody. Also, 2 robustness tests were performed using the SRUC data to test the effect of diet change on BW and the automatic milking system data to test the effect of farm on BW variation. Finally, we combined the results into a blueprint describing different ways to calculate EBbody depending on the purpose and on the availability of BCS. The dynamic RGF adjustment resulted in a lower empty BW during early lactation than that obtained with the previously used constant RGF. The double-exponential smoothing method used to correct for meal-related gut-fill was robust to choice of smoothing parameters. Cows should be weighed at least once every 4 d during early lactation to capture the duration of negative EBbody. Our EBbody method proved robust to diet changes. Finally, although cow BW varied significantly between farms, the quantile regression smoothing of BW did not bias the estimation of weight differences between herds. In conclusion, these results validate the applicability of the EBbody method to estimate EB across a range of farm conditions, and we provided a blueprint that enables the estimation of EBbody for individual cows on-farm using only frequent BW, in combination with BCS when available.

The objective of this study was to evaluate genetic and non-genetic factors influencing artificial insemination (AI) success in French dairy goats. Data analysis, on a total of 584 676 and 386 517 AI records for Alpine and Saanen breed, respectively, collected from 1992 to 2009, was conducted separately on each breed. We used a linear simple repeatability animal model which combined male and female random effect and environmental fixed effects. The most important environmental factor identified was the period within year effect due to the European heat wave of 2003. The estimated values of the annual fertility exhibited a negative trend of 1% loss of AI success per 10 years for Alpine breed only. The range of variation for the flock×within years random effect was 70% and 65% for Alpine and Saanen breeds. The negative effect on AI success of antibody production after repetitive hormonal treatment was confirmed. We observed an important positive relationship between fertility and protein yield expressed as quartile within flock×years of protein 250-day yield for female with lactation number over 1, while this trend was negative for primiparous females. We detected a negative effect of the duration of conservation of semen with a difference of about 4% of AI success between extreme values (2 to 8+ or 9+ years). Heritability estimates for male fertility were 0.0037 and 0.0043 for Alpine and Saanen breed respectively, while estimates for female fertility was 0.040 and 0.049. Repeatability estimates for males were 0.008 and 0.010 for Alpine and Saanen, respectively, and 0.097 and 0.102 for females. With such low values of heritability, selection can hardly affect fertility.

Background Genome-wide association studies (GWAS) were performed at the sequence level to identify candidate mutations that affect the expression of six major milk proteins in Montbéliarde (MON), Normande (NOR), and Holstein (HOL) dairy cattle. Whey protein (α-lactalbumin and β-lactoglobulin) and casein (αs1, αs2, β, and κ) contents were estimated by mid-infrared (MIR) spectrometry, with medium to high accuracy (0.59 ≤ R2 ≤ 0.92), for 848,068 test-day milk samples from 156,660 cows in the first three lactations. Milk composition was evaluated as average test-day measurements adjusted for environmental effects. Next, we genotyped a subset of 8080 cows (2967 MON, 2737 NOR, and 2306 HOL) with the BovineSNP50 Beadchip. For each breed, genotypes were first imputed to high-density (HD) using HD single nucleotide polymorphisms (SNPs) genotypes of 522 MON, 546 NOR, and 776 HOL bulls. The resulting HD SNP genotypes were subsequently imputed to the sequence level using 27 million high-quality sequence variants selected from Run4 of the 1000 Bull Genomes consortium (1147 bulls). Within-breed, multi-breed, and conditional GWAS were performed. Results Thirty-four distinct genomic regions were identified. Three regions on chromosomes 6, 11, and 20 had very significant effects on milk composition and were shared across the three breeds. Other significant effects, which partially overlapped across breeds, were found on almost all the autosomes. Multi-breed analyses provided a larger number of significant genomic regions with smaller confidence intervals than within-breed analyses. Combinations of within-breed, multi-breed, and conditional analyses led to the identification of putative causative variants in several candidate genes that presented significant protein–protein interactions enrichment, including those with previously described effects on milk composition (SLC37A1, MGST1, ABCG2, CSN1S1, CSN2, CSN1S2, CSN3, PAEP, DGAT1, AGPAT6) and those with effects reported for the first time here (ALPL, ANKH, PICALM). Conclusions GWAS applied to fine-scale phenotypes, multiple breeds, and whole-genome sequences seems to be effective to identify candidate gene variants. However, although we identified functional links between some candidate genes and milk phenotypes, the causality between candidate variants and milk protein composition remains to be demonstrated. Nevertheless, the identification of potential causative mutations that underlie milk protein composition may have immediate applications for improvements in cheese-making. Electronic supplementary material The online version of this article (doi:10.1186/s12711-017-0344-z) contains supplementary material, which is available to authorized users.

Towards a European beef eating quality model ?. 19th International Conference on Food Processing and Technology

In France, Lacaune dairy sheep in the Roquefort area are fed in groups with a wide range of milk yields (MY). In order to adapt concentrate levels to MY, a 100-day experiment was conducted during the early milking period (50 days in milk) with three batches of 54 multiparous ewes constituted according to their MY (L/d): high (H: 3.2), medium (M: 2.7) and low (L: 2.2). Each batch was separated into two groups of 27 ewes, a control group (C) and an experimental group (E), fed either with the same level of concentrate (CH, CM and CL) or with concentrates adjusted to the MY (EH, EM and EL), respectively. All ewes were fed a forage mixture ad libitum. The average daily individual forage dry matter intake was not different (P>0.05) between groups EH, CH, EM and CM (2.3 ± 0.17 kg DM), but that of CL (2.0 ± 0.17 kg DM) was lower (P0.05). Body condition score was not affected (P>0.05) by concentrate level in any of the groups. There was no effect (P>0.05) on MY and milk composition. However, the urea level in the milk was lower (P0,05) entre les groupes H et M (2,3 ± 0,17 kg MS), mais celles de CL(2,0 ± 0,17 kg MS) étaient inférieures (P0,05) pour les autres groupes de même que pour l’état corporel. Aucun effet n’a été observé (P>0,05) sur la MY, la composition du lait ou les cellules somatiques. Seule la concentration en urée du lait de EL était inférieure (P

In dairy farming, monitoring tools are developing rapidly and the possibility of combining available data to generate additional information raises new questions. The high throughput body weight is a new and frequent phenotype on dairy farms. Feed intake monitoring in dairy cows remains largely absent, even though it is useful for herd management. The purpose of this work was to predict the dynamics of dry matter intake with a model using live weight, milk production and ration characteristics. This model is based on the assumption that changes in body weight are closely related to dry matter intake through two components: short-term changes in digestive content related to ingestion and long-term changes in body reserves, which are linked to the cumulative energy balance of the cow since calving. The energy balance results from the difference between the energy inputs from the ingested quantities and the energy requirements related to milk production. The model was tested in a trial with 65 cows receiving the same complete ration during the first 18 weeks of lactation. Observed individual intake was predicted well by the model, with average weekly errors of 2.3 kg, although the daily errors are still high (SD = 3.31 kg). Intake prediction during the first month of lactation showed a systematic bias and further investigation will be necessary to understand this bias and correct it.

The reproductive performance of dairy herds is mainly influenced by the physiological reproductive status of the cows and by herd management. The objective of this work was to evaluate the economic benefits of investment in a sensor system for oestrus detection (pedometer or activity meter) in different dairy farming systems in France. A stochastic dynamic model was used to simulate all the physiological and management processes occurring in a dairy operation. Seven French dairy farms with different breeds (Holstein, Montbéliarde and Normande), size (30 to 119 cows), milk price (conventional or protected designation of origin) and calving strategies (grouped or continuous calving) were simulated. Six scenarios with different oestrus detection rates (50% before and 90% after use of the equipment) and percentage of cows equipped (40%-80%-100%) were applied to each farm. The internal rate of return was used to evaluate the economic benefits of the investment. It was estimated that the system for transmitting and analysing data from pedometer and activity meter systems would cost €6,498 and €4,430 respectively. The use of an automatic oestrus detection device reduced the calving interval by between 7d (herds with Normande cows) and 23d (herds with Holstein cows) and increased the annual gross margin per cow by between €8 (small herd with Normande cows) and €92 (herd with Montbéliarde cows). The investment appeared profitable in two-thirds of the situations, characterised by high milk prices, large herd size or low percentage of cows equipped. These results suggest that the return on investment should be estimated at each farm level.

Farmers's practices and attitudes towards artificial fed lambs and their mortality in meat systems. 7. International conference on the assessment of animal welfare at farm and grip level. WAFL 2017

Residual feed intake, usually used to estimate individual variation of feed efficiency, requires frequent and accurate measurements of individual feed intake. Developing a breeding scheme based on residual feed intake in dairy cows is complicated, especially because feed intake is not measurable for a large population. Another solution could be to focus on biological determinants of feed efficiency which could potentially be broadband measurable on farm. Several phenotypes have been identified in literature as being associated with differences in feed efficiency. The present study aims to identify which biological mechanisms are associated with residual energy intake (REI) differences among dairy cows. Several candidate phenotypes were recorded frequently and simultaneously throughout the first 238 days in milk for 60 Holstein cows fed on a constant diet based on maize silage. The REI was defined as the residuals of a linear regression of the lactation average of net energy intake predicted from lactation averages for net energy in milk, metabolic body weight, lactation body condition score loss and gain. A partial least square regression (PLSr) was fitted over all recorded traits to explain REI variability. Linear multiple regression explained 93.6% of net energy intake phenotypic variation, with 65.5% associated with lactation requirement, 23.2% to maintenance, 4.9% to body reserves change. Overall measured traits contributed to 58.9% of REI phenotypic variability, with activity (26.5%) and feeding behavior (21.3%) being the major contributors. However, the level of contribution of each trait was dependent on the variables included in PLSr because REI variability was comparably explained by rumen temperature variation, body reserves change and digestibility when all traits associated with activity and behavior were excluded from PLSr. Drawing a conclusion on biological traits which explain feed efficiency differences among dairy cows was not possible due to this apparent confusion between traits. Further investigation is needed to characterize the causal relationship of feed efficiency with feeding behavior, digestibility, body reserves change, activity and rumen temperature.