Search

International audience; BackgroundShifting towards a more plant-based diet, as promoted in Western countries, will reduce the animal protein contribution to total proteins. Such a reduction may not only impair protein adequacy, but also the adequacy in other nutrients. ObjectivesWe determined, for different adult subpopulations, the minimum total protein level and the minimum animal protein contribution to total proteins that are compatible with the fulfillment of all non-protein nutrient-based recommendations. MethodsMean nutritional content and mean diet cost for 5 French subpopulations were estimated using a French cross-sectional representative survey: Women

A new 5-year Common Agricultural Policy has been in place since January 2023. Like its predecessors, this new policy will fail to deliver significant climatic and environmental benefits. We show how the Green Architecture of the policy relying on the three instruments of conditionality, eco-schemes, and agri-environment and climate measures could have been used more consistently and effectively. Our proposals are based on core principles of public economics and fiscal federalism as well as on research results in agronomy and ecology. Conditionality criteria are the minimal requirements that every agricultural producer must meet. Farmers should be rewarded for efforts that go beyond these basic requirements through eco-schemes for global public goods complemented by agri-environment and climate measures centred on local public goods. Eco-schemes should cover the whole agricultural area by targeting permanent grasslands, crop diversification, and green cover and non-productive agro-ecological infrastructures. We discuss trade-offs that our proposals could generate.

International audience

International audience; Throughout the world, animal production faces huge sustainability challenges. The latter are exacerbated in the European Union (EU) by consumption issues linked, in particular, to the health and environmental impacts of meat consumption, and by the increasing societal concerns linked to animal welfare. Simultaneously, animal production may also provide benefits, notably from an economic and nutritional point of view. Some livestock systems, notably grass-based systems, may also offer positive climatic and environmental effects. Animal production is highly regulated in the EU, whereas the consumption of animal products is not (or very lightly) regulated. Many of the negative and positive effects are public goods that are not well taken into account by private actors and markets. Thus, there is legitimacy and scope for public policies aimed at reducing the damage and increasing the benefits of animal production and consumption. The last part of the paper explains how this could be achieved in the EU through a significantly revised and extended Common Agricultural Policy that more closely follows the principles of public economics. Public regulation principles that are proposed have a more general scope and can be adapted to other livestock contexts.

International audience; Spontaneous lipolysis (SL) impairs the technological and sensory properties of milk and dairy products. Husbandry factors, and especially nutritional factors, are known to modulate SL levels, but the biochemical mechanisms involved remain unclear. We investigated effects of feeding levels and forage types on SL mechanisms. Thirty-two cows were divided into 4 groups according to their diets (corn silage or conserved grass). Two feeding levels were applied: "non-restricted", where cows were fed ad libitum, and "restricted", where cows were fed at 75% of their ad libitum dry matter intake. The trial was conducted in a split-plot design where "forage type" was the main factor and "feeding level" was the sub-factor. Cows were followed for 12.5 weeks: 4 pre-experimental weeks, then a 14-day transition period (to change the forage, and decrease feed intake), a first 3-week experiment period, then a 4-day transition period (to reverse the energy treatment) followed by a second 3-week experiment period. Milk samples were collected from morning and evening milkings at the end of each period to determine milk traits, fat globule size, protein and fatty acid profiles, lipoprotein lipase (LPL) activity, and SL. Data analysis using the SAS-software MIXED procedure found no statistically significant feeding-level x forage-type interactions on SL. Compared to non-restricted cows, feed-restricted cows tended to have higher SL levels in morning milks (0.60 vs 0.52 mEq/100 g fat) and even higher SL levels in evening milks (0.89 vs 0.58 mEq/100 g fat). Cows fed corn silage tended to have higher SL in morning milks (0.72 vs 0.40 mEq/100 g fat) but evening milks showed no forage-type effect. The low feeding level had no effect on milk fat content, fat globule size, LPL activity or protein profile. In both non-feed-restricted and feed-restricted cows, corn silage was associated with lower milk fat content (3.53 vs 3.91%), smaller globule size (d(4,3) : 3.40 vs 3.71 mu m), lower percent proteose peptone 5 and 8 s, but had no effect on LPL activity. Data analysis using the SAS-software REG procedure found that proteose peptone 5 (logarithm-converted) was strongly negatively correlated with SL, suggesting a potential inhibitor effect of proteose peptone 5. Certain milk components are therefore modulators of SL. In morning and evening milks of SL-sensitive cows (defined as SL level up to 0.60 mEq/100 g fat), SL was negatively correlated with C18:0 and fat content and positively correlated with cis9 C18:1/C18:0, suggesting a link between tissue mobilization, mammary metabolism and SL. To sum up, feeding restriction is associated with higher SL, probably due to higher tissue lipid mobilization. Further investigation is needed to determine the impact of corn silage on SL. Variations in proteose peptone 5 levels according to forage type could explain SL levels. These findings could serve for advisory practice and prevention education to farmers.. At a biochemical level, the findings could be used to create tools and tests to detect and monitor lipolysis cow-by-cow.

International audience; Lipolysis is an enzymatic reaction, which leads to off-flavor in milk and impairs technological properties of milk. In some regions of France, lipolysis is one of the milk payment criteria. Cow susceptibility to lipolysis affects tank lipolysis variations. “Non-susceptible” cows’ present low and stable lipolysis rates during their life although “susceptible” cows present fluctuating lipolysis rates, varying with husbandry factors, milking systems and milk storage. According to the type of farming system, lipolysis can be reduced by selecting “non-susceptible“ cows, by drying off “susceptible” cows from 6 months of gestation, and by reducing milking frequency to 2 milkings per day. The balance of rations (energy, proteins, lipid supplements) must be considered, especially in early lactation for high merit multiparous cows. Pasture is associated with low lipolysis rates. Careful maintenance of milking systems is important to reduce dysfunctions and their impacts on lipolysis. Lipolysis is on average higher for milking robots than for conventional milking equipment ; however, continuous improvements are being made in the field. The biochemical mechanisms of lipolysis are still being studied.; La lipolyse est une réaction enzymatique qui influence négativement les qualités organoleptiques et technologiques du lait. Dans certaines régions de France, la lipolyse est un critère de paiement du lait. La susceptibilité des vaches à la lipolyse conditionne les fluctuations de la lipolyse dans le tank. Les vaches dites « non susceptibles » présentent un taux de lipolyse individuel faible et stable pendant leur carrièrealors que les vaches dites « susceptibles » présentent un taux de lipolyse fluctuant de faible à très élevé, en fonction des facteurs d’élevage, de l’installation de traite et du stockage. Selon les systèmes d’élevage, plusieurs leviers sont disponibles pour minimiser la lipolyse : sélection de vaches « non susceptibles » à la lipolyse parmi les vaches Holstein ou recours à d’autres races de vaches moins « susceptibles » telles queles vaches de race Normande ou Tarentaise à titre d’exemple, tarissement à 6 mois de gestation pour les vaches « susceptibles », maintien de la fréquence de traite à deux traites par jour. Une attention particulière doit être accordée à l’équilibre des rations (énergie, azote) et à la complémentation (lipides) surtout chez les vaches fortes productrices en début de lactation. Le pâturage semble être associé à des niveaux de lipolyse faibles. Un bon entretien des installations de traite doit être réalisé car la présence de dysfonctionnements multiplie l’impact du circuit de traite sur la lipolyse. Avec les robots de traite, la lipolyse est en moyenne plus élevée qu’en traite conventionnelle, cependant l’amélioration des matériels est continue. Les mécanismes biochimiques, explicatifs de la lipolyse sont toujours à l’étude.

International audience; Grasslands offer many environmental and economic advantages that put them at the heart of future sustainable ruminant production systems. This study aimed to quantify and map the dry matter yield (DMY) and nitrogen yield (NY) of French grasslands resulting from cutting and grazing practices, based on the existing diversity of grassland vegetation, management, soil and climate conditions, using a research version of the STICS crop model called PâturSTICS. This model simulates daily dry matter (DM), nitrogen (N) and water fluxes involved in the functioning of grasslands and crops in response to management and environmental conditions. It was improved to represent deposition of animal waste on grassland soils during grazing and to simulate DM production and N content of grasses and legumes more accurately. Simulations were performed for locations across France on a highresolution grid composed of pedoclimatic units (PCU) obtained by combining the spatial resolutions of climate and soil. The main grassland types and associated management types were determined for each PCU and then simulated over 30 years (1984-2013). Using the simulated values, predictive metamodels of annual grassland DMY and NY were developed from easily accessible explanatory variables using a random forest approach. Annual model predictions were aggregated and averaged at the PCU scale, then compared to regional observations. Predicted DMY agreed with available observations, except in semi-mountainous and mountainous regions, where PâturSTICS tended to overpredict DMY, probably because it ignores effects of snow, frost and slope, and due to how it represents effects of temperature and water stress on plant growth. According to results, three-quarters of French grasslands produce and export at least 7.6 t DM ha-1 yr-1 and 172 kg N ha-1 yr-1, respectively. One-quarter of French grasslands produce and export at least 10.7 t DM ha-1 yr-1 and 254 kg N ha-1 yr-1, respectively. The latter are located mainly in northwestern France, the north-western Massif Central, the French Alps and the western Pyrénées, all of which have environmental conditions favourable for grass growth. The metamodels developed are interesting proxies for PâturSTICS' predictions of grassland DMY and NY. Our results provided valuable knowledge that promotes better use of the potential forage production of French and European grasslands to improve protein selfsufficiency and N fertilisation management in ruminant livestock systems.

National audience

International audience; Milk spontaneous lipolysis (SL) of milk triglycerides is induced by the lipoprotein lipase, a milk native enzyme, and leads to an accumulation of partial glycerides and free fatty acids that are responsible for the deterioration of the taste of milk products. The gene coding for diacylglycerol acyltransferase 1 (DGAT1), an enzyme implicated in triglycerides synthesis, has an important polymorphic site at the K232A locus. This gene is well known to modulate milk composition. No data are available on the effects of DGAT1 on SL. Thus, a trial was carried out to evaluate the effects of DGAT1 K232A polymorphism on milk SL upon milking frequency variations [once- (ODM) and twice-daily milking (TDM)]. Twenty-one cows were divided into 3 groups according their DGAT1 K232A genotype: 8 cows had the KK genotype of DGAT1 (KK cows), 8 had the KA genotype (KA cows), and 5 had the AA genotype (AA cows). The trial consisted in 3 successive periods: 3 wk of TDM, 3 of ODM, and 4 of TDM. Samples were collected for fat and protein contents, SL, fatty acid, and protein profiles determinations. The KK cows presented higher fat and protein contents, lower milk production, and higher κ-casein percentage. No significant difference in fatty acid composition was noted between groups. The SL was twice as high for KK cows in TDM situations (1.13 vs. 0.59 and 0.63 mEq/100 g of fat, respectively, for KK, KA, and AA cows during the first period of TDM, and 0.46 vs. 0.25 and 0.21 mEq/100 g of fat, respectively, for KK, KA, and AA during the second period of TDM). The SL remained sharply lower in TDM2 than in TDM1. During ODM, no difference in SL was found between groups and SL remained below 0.2 mEq/100 g of fat. These results demonstrate the existence of a correlation between DGAT1 genotypes and spontaneous lipolysis, in interaction with an environmental factor, milking frequency, although it has not been possible to clarify the causal mechanism at this stage.

L’élevage est souvent perçu comme inefficient pour produire des denrées alimentaires pour l’Homme car les animaux consomment davantage de végétaux qu’ils ne produisent de viande, de lait ou d’œufs. Le calcul de l’efficience nette de conversion des aliments en ne considérant dans le calcul que la part potentiellement consommable par l’Homme des aliments utilisés par les animaux permet de relativiser ce constat. En effet, une large part des aliments consommés par les animaux d’élevage (fourrages, coproduits…) n’est pas directement consommable par l’Homme. Appliqués à des systèmes d’élevage français, les calculs d’efficience nette montrent que toutes les productions animales (bovins laitiers et à viande, ovins à viande, porcins, poulets de chair, poules pondeuse) peuvent être producteurs nets de protéines à condition de maximiser la part des végétaux non valorisables en alimentation humaine dans les rations. Le calcul de l’efficience nette est très sensible à l’estimation de la part des aliments utilisés en alimentation animale qui peut être directement valorisée par l’Homme. Celle-ci varie fortement d’une matière première à l’autre selon les habitudes alimentaires et les technologies agroalimentaire qui peuvent évoluer dans le temps. Il est donc nécessaire d’analyser les résultats d’efficience nette à travers plusieurs scénarios de valorisation des matières premières végétales. De même le niveau de valorisation du cinquième quartier de la carcasse des animaux d’élevage pour l’alimentation humaine est très variable et influence sensiblement les résultats d’efficience nette. Enfin, la prise en compte du différentiel de qualité entre les protéines végétales permettrait d’affiner les calculs d’efficience protéique., Livestock is often perceived as inefficient in producing food for humans because animals consume more plants than they produce meat, milk or eggs. The calculation of the net feed conversion efficiency by considering in the calculation only the potentially consumable part of the feed used by the animals makes it possible to relativize this observation. Indeed, a large part of the feed consumed by livestock (fodder, coproducts…) is not directly consumable by humans. Applied to French livestock systems, the net efficiency calculations show that all animal production (dairy and beef cattle, meat sheep, swine, broilers, layer hens) can be net producers of protein provided they maximize the use of non-edible feed for human in diets. The calculation of the net efficiency is very sensitive to the estimation of the part of the feed used in animals which can be directly valorized in human feeding. This part varies greatly from one feed to another depending on the food habits and agri-food technologies that can evolve over time. It is therefore necessary to analyze the results of net efficiency across several scenarios for valuing plant raw materials. Similarly, the level of valorisation of offals and byproducts of farm animals’ carcasses for human consumption is highly variable and significantly influences the net efficiency results. Finally, taking into account the difference in quality between plant and animal proteins would make it possible to refine protein net efficiency calculations.

The ambition of the foresight on livestock farming was to rethink the place, the roles of livestock and how it should be transformed to fully contribute to the development of more sustainable agri-food systems. It was also to identify cross-disciplinary research themes that explore promising fronts of science or methodologies to solve knowledge locks. The foresight was managed by a group of 15 researchers and mobilized a hundred researchers. Based on an analysis of the context and the drivers for the evolution of the systems, we propose a new conceptual framework to think about innovations. Livestock farming must be part of circular agri-food systems in which it must contribute, beyond an increased efficiency of production factors, to the preservation of the quality of the resources and to the production of a food at an affordable price. Systems need to be rethought to be climate-smart and to respond to the health and welfare challenges of animals and people, rethink the linkages between livestock, crop production and territories to maximize recycling and rethink livestock linkages, processing and consumption of livestock products. Innovations should be based on the principles of agro-ecology supplemented by those of the circular economy and mobilizing levers of (bio) technologies and organizational innovation. The text describes 4 major scientific priorities with their research issues and produces recommendations for an action plan., L’ambition de l’Atelier de Réflexion Prospective sur l’élevage a été de repenser la place, les rôles de l’élevage et en quoi il doit se transformer pour contribuer pleinement au développement de systèmes agri-alimentaires plus durables ainsi que d’identifier des thématiques de recherches interdisciplinaires permettant d’explorer des fronts de science ou méthodologiques porteurs d’avenir pour lever les verrous de connaissances. La réflexion a été animée par un groupe de 15 chercheurs et en a mobilisé une centaine. À partir d’une analyse du contexte et des drivers d’évolution des systèmes nous proposons un nouveau cadre conceptuel et des voies de progrès pour penser l’élevage de demain. L’élevage doit s’inscrire dans le cadre de systèmes agri-alimentaires circulaires dans lesquels il doit contribuer, au-delà d’une efficience accrue des moyens de production, à la préservation de la qualité des ressources et à la production d’une alimentation à un prix abordable. Il faut repenser les systèmes pour qu’ils soient climato-intelligents et répondent aux enjeux de santé et du bien-être des animaux et des Hommes ; repenser les liens entre élevage, production végétale et territoire pour maximiser les recyclages et repenser les liens entre élevage, transformation et consommation des produits de l’élevage. Les innovations doivent être basées sur les principes de l’agroécologie complétés par ceux de l’économie circulaire et par la mobilisation des leviers des (bio)technologies et de l’innovation organisationnelle. Le texte décrit quatre grandes priorités scientifiques avec leurs enjeux de recherche et produit des recommandations pour un plan d’action.

Increasing rumen-undegraded protein is one challenge of ruminant nutrition to both meet protein requirements of animals and reduce nitrogen excretion in the environment by increasing nitrogen efficiency. Industrial processes using heat or tanning to reduce rumen protein degradation have certain limitations, such as difficulty in balancing low ruminal degradation and high intestinal digestibility. Reducing the mean retention time (MRT) in the rumen by varying the size and density of particles may be another promising way to increase the rumen-undegraded protein proportion of concentrate feeds and improve the effectiveness of industrial processes. Spherical plastic particles of 3 mean diameter sizes (1, 2, and 3 mm) and 4 densities (0.9, 1.1, 1.3, and 1.5) were used to study the combined effect of size and density on the MRT of particles without interactions with microbial fermentations. Dynamics of fecal excretion of particles were monitored over 106 h (17 sampling times) in a Latin square experiment with 4 lactating cows. Cumulative particle excretion curves were fitted to a double exponential model to calculate total MRT in the digestive tract (TMRT), MRT in 2 compartments (MRT1 and MRT2), and retention time in the intestines' tubular section (TT). Differences in density had a quadratic effect, with densities of 1.1 and 1.3 yielding lower TMRT (29.5 and 31.2 h, respectively) than the densities of 0.9 and 1.5 (TMRT = 64.0 and 51.2 h, respectively). Similar responses were observed for MRT1, which was assumed to be the ruminal MRT for densities 1.1 and 1.3 (8.9 and 10.5 h, respectively) compared with densities 0.9 and 1.5 (39.6 and 22.6 h, respectively). Differences in diameter had a linear effect on TMRT (12.9 h longer for 3 mm than for 1 mm) and on TT. A combined effect of size and density was observed and particle size had no effect on TMRT when density was 1.1 to 1.3; however, outside this range, an increase in particle diameter increased TMRT. Consequently, a density of 1.2 to 1.3 is optimal for the escape of particles. As smaller particles of concentrates lose functional specific gravity more rapidly than larger particles due to their higher fermentation rate, our results, obtained with plastic particles, suggest that a diameter slightly greater than 3 mm seems a compromise to delay the start of fermentation and allow for rapid passage through the reticulo-omasal orifice.

International audience

La Politique agricole commune (PAC) de l’Union européenne (UE) est entrée dans une nouvelle phase de réforme. Après la diffusion d’une première communication de vision en novembre 2017, la Commission européenne a présenté ses propositions législatives le 1er juin 2018. Ces dernières s’inscrivent dans le contexte d’un budget de la PAC ajusté à la baisse d’environ 5% en euros courants, baisse en pourcentage plus marquée pour le deuxième pilier que pour le premier. Cette communication développe, dans un premier temps, une brève analyse des propositions législatives de la Commission européenne pour la PAC de l’après-2020. Dans un second temps, une analyse est proposée sur ce que la recherche peut dire, ou ne peut pas dire, sur quatre thématiques au cœur des débats sur la future PAC, à savoir l’environnement, les risques, l’innovation, et la suralimentation. Les recommandations qui en découlent en matière de politiques publiques et plus spécifiquement d’évolution de la PAC (légitimité et modalités de l’intervention) sont présentées, et en conclusion mises en regard des propositions législatives., The Common Agricultural Policy (CAP) of the European Union (EU) has entered a new phase of reform. After the release of a first vision communication in November 2017, the European Commission presented its legislative proposals on 1 June 2018. These are in the context of a CAP budget adjusted downward by around 5 % in current euros, a percentage decrease more important for the second pillar than for the first. This communication first develops a brief analysis of the European Commission's legislative proposals for the CAP after 2020. In a second step, we propose an analysis on what the research can say or cannot, on four themes at the heart of the debates on the future CAP, namely the environment, risks, innovation, and overnutrition. The resulting recommendations in terms of public policies and notably for the CAP (legitimacy and modalities of measures) are presented, and in conclusion compared to the legislative proposals.

National audience; The Common Agricultural Policy (CAP) of the European Union (EU) has entered a new phase of reform. After the release of a first vision communication in November 2017, the European Commission presented its legislative proposals on 1 June 2018. These are in the context of a CAP budget adjusted downward by around 5 % in current euros, a percentage decrease more important for the second pillar than for the first. This communication first develops a brief analysis of the European Commission's legislative proposals for the CAP after 2020. In a second step, we propose an analysis on what the research can say or cannot, on four themes at the heart of the debates on the future CAP, namely the environment, risks, innovation, and overnutrition. The resulting recommendations in terms of public policies and notably for the CAP (legitimacy and modalities of measures) are presented, and in conclusion compared to the legislative proposals.; La Politique agricole commune (PAC) de l’Union européenne (UE) est entrée dans une nouvelle phase de réforme. Après la diffusion d’une première communication de vision en novembre 2017, la Commission européenne a présenté ses propositions législatives le 1er juin 2018. Ces dernières s’inscrivent dans le contexte d’un budget de la PAC ajusté à la baisse d’environ 5% en euros courants, baisse en pourcentage plus marquée pour le deuxième pilier que pour le premier. Cette communication développe, dans un premier temps, une brève analyse des propositions législatives de la Commission européenne pour la PAC de l’après-2020. Dans un second temps, une analyse est proposée sur ce que la recherche peut dire, ou ne peut pas dire, sur quatre thématiques au cœur des débats sur la future PAC, à savoir l’environnement, les risques, l’innovation, et la suralimentation. Les recommandations qui en découlent en matière de politiques publiques et plus spécifiquement d’évolution de la PAC (légitimité et modalités de l’intervention) sont présentées, et en conclusion mises en regard des propositions législatives.

National audience; This article summarizes the seminar organized by INRA and the consumer association CLCV on the theme “Eating meat: many challenges and impacts” that was held on May 15, 2018 at AgroParisTech. Consumers modify their behavior qualitatively and quantitatively. Attentive to price changes, they seek to be informed about food products and their production methods, and even to influence them. The scientists at INRA, who were present, study the nutritional characteristics of meat products, their impact on health, the cultural aspects and other determining factors for the consumption of meat products, the economy and organization of breeding systems, their environmental impacts, and animal welfare. Due to the scope of these multidisciplinary fields, they were able to answer the questions raised by consumers by highlighting the complexity of agricultural and food issues in a French, but also European and global perspective. The synthesis presented here seeks to report on the researchers' presentations by integrating their answers to the questions asked by the audience.

Partie 2 : Les besoins des animaux et leurs réponses aux rations; National audience

International audience; The effects on milk, butter and hard cooked cheese of new n-3 fatty acid (FA) sources in cows' corn silage-based diets – microalgae DHA Gold® (ALG), sieved extruded linseed (SEL) and their combination (SEL/ALG) – were assessed. Butter processing from ALG and SEL/ALG cream was not possible. Butter from SEL had less yellow colour and tended to be softer, with less rancid flavour and odour but stronger cream flavour. For SEL/ALG, cheese yield before brining was higher, but fat content in dry matter and curd dry matter were lower. For ALG and SEL/ALG, cheeses were evaluated as less coloured, more open, less firm, less elastic, more grainy and spicy. Cheese volatile compounds were affected by cows’ diet; higher concentrations of compounds from FA oxidation and amino acid catabolism were observed with the addition of microalgae DHA Gold®. Flavour profiles of cheeses were slightly affected by this addition, but no off-flavour was perceived.

National audience

International audience

Les facteurs de variation de la composition en Acides Gras (AG) du lait ont été évalués en 2010 dans 1 528 élevages bovins, caprins et ovins laitiers. Le stade de lactation influe sur la proportion d’AG Saturés (AGS) avec une augmentation jusqu’à 4 mois, forte en bovins, plus modérée en caprins et ovins. La part des AG MonoInsaturés (AGMI) évolue inversement, alors que celle des AG PolyInsaturés (AGPI) reste relativement stable tout au long de la lactation. L’âge à la première mise bas affecte peu la composition en AG chez les bovins et les caprins, mais davantage chez les ovins pour lesquels la part des AGS augmente avec l’âge. Chez les bovins, la période de vêlage a peu d’effet sur le profil en AG, mais la saison de production influence notablement le pourcentage des AGS du lait, dans le même sens que le taux butyreux du lait qui est minimal en période de jours longs. Cette saisonnalité est moins importante en caprins, elle est confondue avec la saison de pâturage en ovins. Les régimes alimentaires ont davantage d’influence sur la composition du lait chez les bovins que chez les petits ruminants. Seule la présence du pâturage influence les grandes familles d’AG du lait, dans le même sens pour les 3 espèces, avec une diminution systématique et d’ampleur modérée (petits ruminants) à forte (bovins) de la part des AGS par rapport au régime de référence. En contrepartie, les pourcentages des AGMI et AGPI ont tendance à augmenter avec l’herbe jeune fraîche. L’effet des autres régimes alimentaires, contenant des fourrages conservés, sur les principales familles d’AG du lait est moins net.

Methods to assess the consequences of mitigation scenarios on greenhouse gas (GHG) emissions in the cattle sector have been widely developed. A crucial issue of these methods is handling the co-products in emissions allocation. In the cattle sector, milk and beef production systems are closely interconnected because of the meat obtained from dairy culled cows and fattened surplus calves. To fully evaluate a change in the dairy sector, the change in the meat production induced should also be taken into account. With this objective, a national cattle population model was developed, based on three sub-models. The herd functioning sub-model represents the bunch of cattle trajectories generated by reproductive and finishing processes depending on breeds, production levels and finishing types. Assuming a steady state herd, the demographics sub-model represents the number of animals in age groups depending on trajectories length. The production sub-model represents the number of animals slaughtered or exported, the quantity of carcasses, milk and direct GHG emissions. The model was calibrated on French data. The simulation of a reference scenario reflecting the French situation in 2010 confirmed that the model allowed linking cattle trajectories, demographics and production of milk, meat and direct GHG emissions. Scenarios for the dairy sector were simulated to illustrate the potential of such modelling approach to evaluate direct GHG emission at the national level. The results confirmed that the interconnection between dairy and beef sectors can modify the benefit of strategies such as dairy intensification. Further, the results also demonstrated that the compensation between beef and dairy cattle to achieve production objectives lead to a change in the type of carcass produced due to differences between breeds and finishing strategies. Accounting for such differences allows deepening the evaluation of the consequences of GHG mitigation options.

For many years, we have seen an increasing specialization of agricultural systems and territories, with a clear separation between territories with very high animal densities and those devoted to the growing of annual crops. This development is explained by market and sector economic logic and has been reinforced by the availability of low-cost inputs and animal housing systems based on direct grazing not requiring straw. It has, however, also involved negative environmental impacts and, in some cases, the impoverishment of soil fertility, a loss of biodiversity, and excesses of N and P, leading to eutrophication and hot spots of ammonia emission in livestock-breeding territories. Having recapped the mechanisms behind the specialization of systems and territories, we examined the extent to which the development of innovative mixed-farming systems that reconnect livestock and crop production on various territorial scales (farm, district, region) can reduce the negative impacts of agriculture on the environment, produce valuable ecosystem services and achieve acceptable economic efficiency for farming enterprises. Examples from temperate regions will be used to show that mixed-farming systems increase the possibilities of better recycling of nutrients within systems, limiting recourse to the purchase of increasingly expensive inputs and safeguarding the biodiversity of agricultural ecosystems.

Révision de la directive européenne sur l’expérimentation animale : qu’en est-il pour la recherche agronomique ?

European grassland-based livestock production systems face the challenge of producing more meat and milk to meet increasing world demands and to achieve this using fewer resources. Legumes offer great potential for achieving these objectives. They have numerous features that can act together at different stages in the soil–plant–animal–atmosphere system, and these are most effective in mixed swards with a legume proportion of 30–50%. The resulting benefits include reduced dependence on fossil energy and industrial N-fertilizer, lower quantities of harmful emissions to the environment (greenhouse gases and nitrate), lower production costs, higher productivity and increased protein self-sufficiency. Some legume species offer opportunities for improving animal health with less medication, due to the presence of bioactive secondary metabolites. In addition, legumes may offer an adaptation option to rising atmospheric CO2 concentrations and climate change. Legumes generate these benefits at the level of the managed land-area unit and also at the level of the final product unit. However, legumes suffer from some limitations, and suggestions are made for future research to exploit more fully the opportunities that legumes can offer. In conclusion, the development of legume-based grassland–livestock systems undoubtedly constitutes one of the pillars for more sustainable and competitive ruminant production systems, and it can be expected that forage legumes will become more important in the future.

Les auteurs soulignent dans l’introduction le risque inhérent à un exercice de prospective pour les élevages laitiers et le lait demain qui est tributaire de nombreuses variables peu maîtrisées. Ils rappellent les principaux atouts du lait, de l’élevage laitier et de la filière laitière française au regard des tendances de la demande mondiale, mais soulignent aussi les fragilités auxquelles la filière laitière, dans son ensemble, et la filière française en particulier, devra s’efforcer de répondre. Il s’agit à court terme des questions relatives à sa compétitivité mais également, l’érosion de son image et de son attractivité, son impact sur la santé de la population ou sur l’environnement. Un état des lieux de la situation actuelle est dressé, qui permet de souligner que tant les filières amont qu’aval se sont restructurées, et que cette tendance va se poursuivre, accompagnée d’une forte mutation du modèle social en production laitière. Les auteurs décrivent ensuite les principaux déterminants pour une filière durable, de l’amont à l’aval. Les axes de progrès majeurs pour le développement d’un secteur laitier compétitif et répondant aux attentes sociétales résident dans l’amélioration de l’efficacité de l’animal et du troupeau, l’autonomie et la sécurité de l’alimentation des troupeaux, l’amélioration des conditions de travail des éleveurs, une meilleure intégration des exploitations d’élevage au sein des territoires, une meilleure utilisation des innovations technologiques et organisationnelles, l’amplification des démarches de qualité, une veille et un « benchmarking » avec les pays et les secteurs concurrents notamment en termes d’innovation et un meilleur dialogue entre amont et aval pour l’adaptation du lait aux besoins de la transformation. En complément de ces actions clés pour assurer la durabilité de la filière laitière, d’autres pistes d’actions sont suggérées, dont l’élaboration d’une véritable stratégie de filière à même d’orienter les politiques publiques et de rapprocher les acteurs de la recherche-développement et de l’innovation.

National audience

Spontaneous lipolysis (SL) is an enzymatic reaction which leads to a release of free fatty acids that can modify technological and sensory properties of milk and milk products. However, few studies have been done to assess the effect of feeding systems (FS) and breed on SL. Most of them were conducted in the 1980s and are not fully representative of cattle today. No previous study investigated the effect of cow breed at the whole-lactation scale. Thus, a trial was carried out to study the effects of 2 FS (high- and low-input FS) with 2 breeds [Holstein (HO) and Normande (NO)] during 1 entire lactation. Sixty-three cows were followed throughout 1 lactation. Cows were divided into 4 groups according to their breed and their FS. The high FS (HFS) consisted of a high-energy diet (in winter, corn silage with 30% concentrate; otherwise, pasture with 4 kg/d of concentrate) and the low FS (LFS) consisted of a low-energy diet (in winter, conserved grass with no concentrate; otherwise, pasture with no concentrate). The cows calved between January and March. Individual milk samples were collected every month from both morning and evening milkings for fat, protein, milk fat globule size, major fatty acids and proteins profiles, and SL determinations. Data were analyzed using the mixed procedure of SAS. The SL was higher in evening milks compared with morning milks. In early lactation, in evening milks, SL was higher in LFS than in HFS. No difference was shown according to the FS in mid and late lactation. Pasture was associated with low SL rate in mid lactation. The NO cows were less susceptible to SL during the entire lactation than HO cows. Finally, early and late lactation periods were identified as being more susceptible to SL, but this depended on breed and FS. During early lactation, HO cows and LFS were associated with higher levels of SL, particularly in evening milks, and, during late lactation, HO cows were associated with higher levels of SL. No intertreatment or intercow correlations (coefficient of determination

Les prairies françaises : production, exportation d'azote et risques de lessivage

The food transition process is now occurring much more quickly in developing countries than in developed nations, where it took over more than a century to achieve it. Two essential consequences of this process are a switch in the domestic utilization of cereals from human consumption to feeding of livestock and a much greater growth rate of meat and milk production today in developing countries than in developed nations. However, many developing countries continue to consume more animal products than they produce, and hence, are still dependent on imports for satisfying their increasing needs. They depend on trade not only directly through imports of animals and animal products, but also indirectly through imports of cereals and oilseeds for animal feed. The prospects are that the developing world will continue to drive world demand for all agricultural products, including animal products, in the next decades, and agricultural trade should increase. Current trends and future prospects raise the issue of how to ensure access to international and regional agricultural markets and stabilize food prices. This is exacerbated by the fact that exports, more specifically exports in animals and animal products, are highly concentrated among a few key players. Animal production does not have to be condemned because of its drawbacks that should urgently be addressed with the aim of reducing their energy and environmental footprint. More specifically, trade issues include international trade rules, food safety, and harmonization of environmental and animal welfare rules.

Providing phenotypic information, which is accurate, reliable, repeatable and comparable across countries or laboratories, is critical to gain a better understanding of the relationship between genes and phenotypes. So far, it is indeed extremely difficult to combine different sources of phenotypic data from multiple origins, partly because of the variability in the methods of phenotyping. The phenotyping program of livestock involves the definition of complex phenotypes obtained from data integration at different levels (from molecules to herds), the implementation of the latest technologies to accurately characterize at high speed and low cost, the greatest number of animals in a better characterized environment, and the development and sharing of large databases for data analysis and modeling. Such a program also involves the construction of a coordinated network of research and professional facilities and a common language with shared definition of unambiguous animal traits and of methods to assess them. To this end, it will build on the ‘Animal Trait Ontology of Livestock’ (ATOL) project with the objective of defining precisely the phenotypes of interest for farm animals. Then, it will be necessary to combine an environmental information system related to animal husbandry and associated methods to capture the phenotypic differences between animals.

The effect of pre-grazing herbage mass (HM) on herbage intake and milk production of strip-grazing dairy cows is usually studied at the same herbage allowance (HA). In the literature, the effect of HM seems to be affected by the cutting height above which HA is estimated. The aim of this 2 · 3 factorial study was to determine whether the effect of HM (low vs high HM) on herbage intake, milk production and grazing behaviour of dairy cows is affected by the HA estimation height (ground level vs 2AE5 vs 5 cm). Two HMs were compared in three different ways: at same HA above ground level (SHA0), at same HA above 2AE5 cm (SHA2) and at same HA above 5 cm (SHA5). During two consecutive years, twentyfour Holstein-Friesian dairy cows in mid-lactation were assigned to one estimation height in an incomplete switchback design, with two 14-d periods. There was an interaction between HM and estimation height for herbage intake and milk production. The effect of HM on herbage intake was positive, null and negative when HMs were compared at SHA0, SHA2 and SHA5, respectively. This study may have practical implications on future research for studying, directly or indirectly, the effect of pre-grazing HM under strip- or rotationalgrazing management, and on modelling herbage intake at grazing.

Following recent publication of data on its environmental impact, beef production is being strongly challenged. However, these data concern global ruminant production, which is highly diverse and does not necessarily correspond to the European and French situations. While it is undeniable that ruminant production contributes to global warming, there are several ways of mitigating greenhouse gas emissions, and permanent pastures serve as carbon sinks. Beef production is also a vital economic sector for many regions, where it would not be possible to produce cereals or to develop intensive animal production systems. Beef production also contributes to many collective services, justifying its continued financial support.

International audience; Grazing low-mass pastures is almost inevitable when extending the grazing season into late winter to reduce feed costs, cows' performance being potentially affected. An experiment was carried out to estimate the performance, pasture intake (PI) and behavioural adaptation of dairy cows when grazing low-mass pastures at LOW. MEDIUM and HIGH pasture allowances (PA), corresponding to 19,32 and 46 kg OM/cow per day above ground level, respectively. The study took place in the late winter of 2008 on good quality perennial ryegrass/white clover pastures with a mean pasture mass and a pre-grazing platemeter height of 2.3 t OM/ha above ground level and 5.8 cm, respectively. Each cow was supplemented with 4.4 kg OM of maize silage and 2.0 kg OM of cereal concentrate. Daily time at pasture was restricted to 9 h between the am and pm milkings. Eighteen midlactation Holstein cows (twelve multiparous and six primiparous) were used in a 3 x 3 orthogonal Latin square design with three consecutive periods of 13 days. On average, the cows produced 25.3 kg of milk and total OM intake was 14.4 kg/d. Pasture OM intake averaged 7.9 kg/d and linearly increased from LOW to HIGH (+ 0.04 kg/kg PA). Similarly, milk production per cow ( + 0.09 kg/kg PA) and milk protein concentration (+ 0.04 g/kg per kg increase in PA) linearly increased with increasing PA. Milk fat concentration, on the other hand, decreased by 0.10 g/kg per kg increase in PA. The daily grazing time (430 min) and the proportion of time spent grazing (79%) were not affected by PA. On average, pasture intake rate was low (19 g OM/min) and linearly increased from 16.9 g OM/min in LOW to 20.7 g OM/min in HIGH. In the present study, the PI was limited even at high PA because of the cumulative effect of the low-mass pasture (low intake rate) and the restricted access time (short grazing time). Consequently, the effect of PA on PI was low. However, the milk production response to variations in PI was high because of the low energy balance recorded in all treatments. (C) 2010 Elsevier B.V. All rights reserved.

International audience; The prediction of both food intake and milk production constitutes a major issue in ruminants. This article presents a model predicting voluntary dry matter intake and milk production by lactating cows fed indoors. This model, with an extension to predict herbage intake at grazing presented in a second article, is used in the Grazemore decision support system. The model is largely based on the INRA fill unit system, consisting of predicting separately the intake capacity of the cows and the fill value (ingestibility) of each feed. The intake capacity model considers potential milk production as a key component of voluntary feed intake. This potential milk production represents the energy requirement of the mammary gland, adjusted by protein supply when the protein availability is limiting. Actual milk production is predicted from the potential milk production and from the nutritional status of the cow. The law of response of milk production is a function of the difference between energy demand and actual energy intake, modulated by protein intake level. The simulation of experimental data from different feeding trials illustrates the performance of the model. This new model enables dynamic simulations of intake and milk production sensitive to feeding management during the whole lactation period.

International audience; This study investigated the effects of the forage-to-concentrate (F:C) ratio and the rate of ruminal degradation of carbohydrates from the concentrate on digestion in dairy cows fed corn silage-based diets. Six cows with ruminal cannulas were assigned to 6 treatments in a 6 x 6 Latin square. Treatments were arranged in a 3 x 2 factorial design. Three proportions of neutral detergent fiber from forage [FNDF; 7.6, 13.2, and 18.9% of dry matter (DM)] were obtained by modifying F:C (20:80; 35:65, and 50:50). These F:C were combined with concentrates with either high or low content of rapidly degradable carbohydrates. The dietary content of rapidly degradable carbohydrates from the concentrate was estimated from the DM disappearance of concentrate after 4 h of in sacco incubation (CRDM). Thus, 2 proportions of CRDM were tested (20 and 30% of DM). Wheat and corn grain were used as rapidly and slowly degradable starch sources, respectively. Soybean hulls and citrus pulp were used as slowly and rapidly degradable fiber sources, respectively. Concentrate composition was adjusted to maintain dietary starch and neutral detergent fiber contents at 35.9 and 28.9% of DM, respectively. There was no effect of the interaction between F:C and CRDM on DM intake (DMI), ruminal fermentation, chewing activity, and fibrolytic activity. When F:C decreased, DMI increased, the mean ruminal pH linearly decreased, and the pH range linearly increased from 0.95 to 1.27 pH unit. At the same time, the acetate-to-propionate ratio decreased linearly. Decreasing F:C linearly decreased the average time spent chewing per kilogram of DMI from 35.2 to 19.5 min/kg of DMI and decreased ruminal liquid outflow from 11.6 to 9.2 L/kg of DMI, suggesting a decrease in the salivary flow. Increasing CRDM decreased DMI and increased the time during which pH was below 6.0 (3.1 vs. 4.8 h), the pH range (0.90 vs. 1.33), and the initial rate of pH drop. It also increased the volatile fatty acid range (35 vs. 59 mM), thus suggesting an increased rate of fermentation. It also decreased the acetate-to-propionate ratio (2.9 vs. 1.8). Increasing CRDM barely affected the average time spent chewing per kilogram of DMI and the ruminal liquid outflow. These results suggest that rumen pH is controlled by different mechanisms when F:C is decreased or when CRDM is increased. Consequently, FNDF is a good predictor of the chewing time, whereas CRDM is a good predictor of the pH range and volatile fatty acid profiles. Finally, considering both FNDF and CRDM improves the prediction of mean pH.

International audience; Background: The 2 major dietary sources of trans fatty acids (TFAs) are partially hydrogenated oils and ruminant-derived products. Epidemiologic data suggest that chronic consumption of industrial sources of TFAs could be damaging to insulin sensitivity, but intervention studies on this issue have remained inconclusive. Objective: The trial was designed to compare the effects of dairy compared with industrial sources of TFAs on insulin sensitivity in overweight women. Design: Sixty-three healthy women with abdominal obesity [waist circumference > 88 cm and a body mass index (in kg/m(2)) > 28] were recruited. After a run-in period, the volunteers were randomly assigned to consume 1 of 3 four-week diets: 60 g low-TFA lipids/d (0.54 g/d; n = 21), ruminant TFA-rich lipids (4.86 g/d; n = 21), or industrial TFA-rich lipids (5.58 g/d; n = 21). Changes in peripheral insulin sensitivity were assessed by using hyperinsulinemiceuglycemic clamps. Results: After the intervention period, fasting glycemia and insulinemia and insulin sensitivity were not significantly modified in either group (P > 0.05). Conclusions: These data indicate that consumption of dairy- and industrial-source TFAs for 4 wk at nutritional levels do not impair peripheral insulin sensitivity in insulin-resistant women. Our study may not preassess the effects of TFAs in normal insulin-sensitive individuals. This trial was registered at clinicaltrials.gov as NCT00617435. Am J Clin Nutr 2009;90:88-94.

Improving food practices of high producing animals is required to avoid important economic losses. The dietary anion-cation difference, described as [sodium] + I potassium ]-[ chlorine], should aid in preventing metabolic disorders caused by acid production. From three databases (dairy cows, growing pigs and growing ruminants), performance and acid-base status responses on an increase of dietary cation-anion difference were studied by a covariance analysis. Intake, 4% fat corrected milk and average daily gain increased with increasing dietary cation-anion difference. At the same time, blood pH and blood bicarbonate concentration increased whereas blood chlorine decreased, suggesting that chlorine is the main ion implicated in the acid-base regulation. The urinary pH increased with increasing dietary cation-anion difference and it was highly correlated with the dietary cation-anion difference. Renal excretion was the main way to excrete ions and urinary pH seemed to be a good predictor of dietary cation-anion difference. The results suggest that an increased dietary cation-anion difference could prevent metabolic disorders due to an intense metabolism. Moreover, the results suggest that the main way to improve performances is based on a systemic level, even though a rumen effect could explain the difference between ruminants and pigs., La maîtrise de l’alimentation des animaux à fort niveau de production est nécessaire pour éviter des pertes économiques importantes. Parmi les pistes explorées, le bilan électrolytique, défini comme [sodium] + [potassium]-[chlore], est une voie intéressante pour limiter la production d’acides à l’origine de troubles métaboliques. A partir de trois bases de données (vaches en lactation, porcs en croissance et ruminants en croissance), cette synthèse étudie par analyse de covariance, les réponses zootechniques et celles de l’homéostasie acido-basique en fonction de la valeur du bilan électrolytique de la ration. Les quantités ingérées, la production de lait à 4% et le gain moyen quotidien augmentent avec l’augmentation du bilan électrolytique. Dans le même temps, le pH et les concentrations en bicarbonates du sang suivent la même évolution. La chlorémie diminue fortement avec l’augmentation du bilan électrolytique : le chlore est l’ion le plus impliqué dans la régulation de l’homéostasie acido-basique. Enfin, le pH urinaire augmente avec l’accroissement du bilan électrolytique de la ration, la corrélation obtenue est très forte. La voie urinaire est donc la principale voie d’excrétions des ions, et le pH urinaire pourrait être un bon indicateur de la valeur du bilan électrolytique des rations distribuées. L’augmentation du bilan électrolytique de la ration est donc un moyen efficace de lutter contre la production d’acides liée au métabolisme intense des animaux à fort potentiel de production. L’homogénéité des résultats entre les différents modèles suggère un effet du bilan électrolytique à un niveau systémique, même si quelques différences entre ruminants et monogastriques laissent à penser un effet au niveau du rumen

Thanks to PhenoFinlait program many knowledge and applications were developed regarding fine milk composition analysis, links between milk composition and farming systems, genetic determinism of milk fatty acids and proteins. Those results are based on a large scale data collection covering about 1,500 commercial farms. French dairy cattle, sheep and goat industries have now access to estimation equations for fatty acids and proteins based on mid infra-red spectra (MIR); very precise qualitative and quantitative analyzing method for milk proteins; references and tools to control milk composition by monitoring dairy females and animal feeding; reference populations for genomic selection and knowledge on genetic determinism of milk fatty acids and proteins profiles. Moreover, thanks to PhenoFinlait program, French research and dairy industries get a huge experience on MIR spectral data; large data-base and sample banks (milk and DNA) available for new developments both to go further on fine milk composition, or to investigate new topics (milk production traceability, animal health and reproduction monitoring, enteric methane emission ...). Appropriation and valorization by the different French dairy industries stakeholders is going on, but a lot of work and efforts still has to be done for accompanying field actors in relevant implementation improving competitiveness of their process. Besides, many new research projects come directly from PhenoFinlait program or are partially based on its data, samples and know-how. It is very likely that it will generate new knowledge, references and applications of interest for French researchers, farmers and dairy industries., Le programme PhénoFinlait a permis de nombreux développements en matière d’analyse du lait, de mise en relation des facteurs d’élevage et d’alimentation avec la composition fine du lait, et de déterminisme génétique des acides gras et protéines. Cela a été permis, en particulier, par un suivi de quelques 1500 fermes privées. Les filières laitières françaises, bovines, caprines et ovines, disposent, à l’issu de ce programme d’équations d’estimation en routine à partir des données spectrales MIR de la composition fine du lait en acides gras et protéines ; d’une nouvelle méthode hautement résolutive d’analyse qualitative et quantitative des protéines du lait ; de référentiels sur les liens entre les systèmes d’élevage et d’alimentation et la composition fine du lait, allant jusqu’à un outil de prédiction de sa composition en quelques acides gras d’un mois sur l’autre ; de populations de référence pour l’évaluation génomique et plus généralement d’une connaissance du déterminisme génétique de ces caractères. Au-delà de ces résultats, le programme PhénoFinlait est également à l’origine de méthodologies relatives à l’exploitation des spectres MIR éprouvées ainsi que de bases de données et de banques d’échantillons (lait et ADN) conséquentes, aisément mobilisables pour aller plus loin dans la caractérisation fine du lait ou pour explorer d’autres domaines (traçabilité des modes de production, suivi des animaux - santé, reproduction -, rejets de méthane entérique…). L’appropriation et la valorisation de ces acquis par les différentes filières est en cours, mais elle est encore très partielle car un travail conséquent d’explication et d’analyse cas par cas des modalités de valorisation les plus adaptées est nécessaire. Par ailleurs, plusieurs nouveaux projets sont issus ou s’appuient en partie sur l’investissement initial PhénoFinlait. Gageons que cela génère encore pendant plusieurs années des connaissances, références et outils nouveaux pour la recherche, les éleveurs et les filières françaises.