Modèle d’estimation des émissions de méthane entérique prenant en compte la diversité des ressources alimentaires et la gestion du système (DREEM): étude de cas du pastoralisme dans le Sud de la France

National audienceRuminant livestock systems are significant sources of greenhouse gases. Herd mobility is a high- ly adaptive strategy to increase food availability and to face annual variability of forage resources in harsh conditions. Herd mobility also gives the opportunity for increasing flock size and also the farm productivity. The present study aims to estimate enteric methane (CH4) of French Mediterranean sheep farming systems, especially those utilising diversified pastoral feed resources, using a simulating model (Diversity of feed REsources and Enteric Methane emissions, DREEM). Four chosen case studies were representative of con- trasted farming system and herd mobility in the French Mediterranean systems, varying from low (sedentary) to high (permanently transhuming) farming systems. First results indicate that CH4emissions (kg/year) of farming systems increase together with herd size and mobility. At individual level, enteric CH4 missions from sedentary system ewes were the highest, mainly due to feed intake and feed characteristics. This methodology requires improvements regarding feeding characterization and a larger farming systems sampling. Finally, these results have to be analyzed at a global level by estimating total GHG emissions of the farm, according to economic and LCA models of farming systems.L’élevage de ruminants est une source importante de gaz à effet de serre (GES). La mobilité du troupeau est une excellente stratégie d’adaptation permettant d’augmenter l’accessibilité et parer à la variabilité annuelle des ressources fourragères en conditions difficiles. L’étude vise à estimer le niveau d’émission de méthane entérique (CH4) de systèmes de production ovine en zone méditerranéenne, en particulier dans le cas d’utilisation des ressources fourragères pastorales diversifiées, ceci en utilisant le modèle de simulation DREEM (de la diversité des ressources fourragères et des émissions de méthane entérique). Quatre cas d’étude ont été choisis représentatifs de systèmes ovin méditerranéens français contrastés et avec différents degrés de mobilité, allant de faible (sédentaire) à très élevé (double transhumant). Les premiers résultats indiquent que les émissions de CH4 (kg/an) des systèmes ont augmenté en même temps que la taille et la mobilité du troupeau. Au niveau animal, les émissions de CH4 entérique des brebis en systèmes sédentaires sont les plus élevées et ceci est principalement dû aux quantités ingérées et à la nature de l’alimentation. Des améliorations méthodologiques sur la caractérisation de l’alimentation et un plus grand échantillon de systèmes sont nécessaires. Enfin, ces résultats doivent être analysés à l’échelle globale en estimant les GES de la ferme grâce à des modèles de bilans économiques et de GES à l’échelle des systèmes de production

DREEM: model on enteric methane emissions in sheep farms

International audienceRuminant livestock systems are significant sources of greenhouse gases. Herd mobility is known as a major adaptation strategy regarding seasonal availability of forage resources. The present study aims at quantifying enteric methane (CH4) emissions from French Mediterranean sheep farming systems, especially the use of diversified pastoral feed resources, using a simulation model (Diversity of feed REsources and Enteric Methane emissions, DREEM). DREEM model was developed to estimate animal enteric CH4 emissions from empirical equations and to be subsequently integrated, as a sub-model, to an economic and GHG balance model (OSTRAL) at the whole farm level. Several equations were chosen from literature data to estimate enteric CH4 emissions. Forage and Feed natures, animal feeding level and performances were referenced according to INRA feeding system and tables. DREEM was applied to the analysis of four case studies covering main contrasted mobility and farming systems situations: from sedentary to highly mobile pastoral systems, in the French Mediterranean area. Overall, equation 1 always gave higher enteric CH4 estimates than the 3 other ones and small variations were observed between the four equations as the standard deviation within each farming system varied from 2.0 to 3.1 g/kg DMI and from 1.1 and 1.6 kg/head/year. At the individual level, enteric CH4 emissions (g / d) of ewes in sedentary system are higher than those of ewes in other systems. These differences are mainly due to differences in animal feeding level and feed resources characteristics in these systems. DREEM model could estimate enteric CH4 emissions at the animal level and be combined to OSTRAL

An enteric methane emission calculator (DREEM) built to consider feed diversity: Case study of pastoral and sedentary farming systems

International audienceRuminant livestock systems are significant sources of greenhouse gases (GHG). Livestock farming in regions with extreme climatic events have to face both scarcity and variability in feed resources. Herd mobility is a known major adaptation strategy to address seasonal availability of forage resources: it allows an increase in herd size, thereby improving labor productivity. The present study quantifies enteric methane (CH4) emissions from French Mediterranean sheep farming systems, focusing on the use of diversified pastoral feed resources, and developing a calculator (Diversity of feed REsources and Enteric Methane emissions, DREEM). The DREEM calculator was developed to estimate at the animal level enteric CH4 emissions (g/day) from empirical equations and be subsequently integrated, as a sub-table, into an economic and GHG (kg/year) balance model (Outil de Simulation du TRoupeau ovin ALaitant, OSTRAL) at the whole farm level. Several equations were taken from the literature to estimate enteric CH4 emissions in DREEM calculator. Nature of forage and feed, animal feeding levels and performance were referenced according to the animal feeding system and tables in France and taking into account the French Mediterranean area studied. DREEM was used to estimate enteric CH4 emissions from four sheep farming systems covering the main contrasting mobility and situations, from sedentary to highly mobile pastoral systems, in the French Mediterranean area. At the individual level, enteric CH4 emissions (g/ day) of ewes in the sedentary system were slightly higher than those of ewes in other systems. These differences were due mainly to differences in animal feeding level (intake / body weight) and feed resources characteristics. Overall, enteric CH4 emissions of ewes and rams were slightly lower than French national inventory estimates. When enteric CH4 emissions of lambs were expressed in g/kg of carcass, were lower in the less pastoral farming systems than in the other systems, because lambs' average daily gains were higher. In double transhuming farming systems, lambs late slaughtering age led to lamb's CH4 contribution of 15% vs 2-5% in the other systems. Flock management, which depends on land use and ownership, greatly contributed to these results

Evaluating animal mobility in relation to climate change mitigation: Combining models to face methodological challenges

National audiencePastoral farming systems are likely to adapt to climate change through animal mobility and thus the potential of available forage resources depending on the season. However, the role of animal mobility in mitigation strategies is not yet known. To understand its role, we investigated major methodological challenges: (i) we addressed the diversity of grazing areas and forage resources mobilized by these systems to estimate methane enteric emissions; (ii) we analyzed the functioning of farming systems based on various combinations of resources use in relation to the assessment of their GHGs and energy requirements (iii) we assessed the impacts on soil and biomass carbon flows caused by grazing practices (carbon sequestration/emission). We developed a methodology based on existing models (OSTRAL and CASA) that we adapted and used in combination. This method was applied to four French Mediterranean farming systems that used mobility differently. Results from OSTRAL model showed that two systems improved efficiency. In the first system, using great quantities of grazing resources from natural areas reduced GHG emissions. In the second system, high animal productivity balanced the increase in GHG emissions caused by feed production. Moreover, CASA model can simulate scenarios of land cover dynamics in natural environments used for grazing. It will help us to assess the impact of grazing practices and thus carbon flows in systems in natural environments. To conclude, this first application shows that the practice of animal mobility off the structural limits of the farm seems engaging to reduce GHG emissions and to improve energy balance

Enteric methane emission model considering diversity of feed resources and system management (DREEM): Case study of pastoralism in Southern Region of France Methane prediction in sheep production systems in south of France

Les systèmes d'élevage de ruminants sont des sources importantes de gaz à effet de serre (GES) (Gerber et al., 2013). La mobilité est une excellent e stratégie d'adaptation concernant la disponibilité et la variabilité annuelle des ressources fourragères, la possibilité d'augmenter la taille du troupeau et donc la productivité de l’activité. L’étude vi se à estimer le méthane entérique (CH 4 ) de systèmes de production ovine en méditerranée, en particulier l'utilisation des re ssources fourragères pastor ales diversifiées, en utilisant un modèle de simulation (de la diversité des ressources fourragères et des émissions de CH 4 , DREEM). Quatre cas ont été choisis représentatifs de systèmes contrastés et de degrés de mobilité, allant de faible (sédentaire) à très élevé (double transhumant ). Les premiers résultats ont montré une relation négative entre la mobilité et les émissions de CH 4 concernant les systèmes les plus contrastés. Au niveau animal, les émissions de CH 4 entérique des brebis en systèmes s édentaires plus élevées. Ceci est principalement dû aux quantités ingérées et à la natu re de l’alimentation. Toutefois, la gestion du troupeau, qui dépend de l’accès aux ressources et de leurs usages module ces résultats. Des améliorations méthodologiques sur la caractérisation de l'alimenta tion et un plus grand échantillon de systèmes sont nécessaires. Enfin, ces résultats doivent être analysés à l’échelle de l’exploitation grâce à des modèles de bilans économiques et de GES des syst èmes agricoles (Benoit et al., 2010).Ruminant livestock systems are significant sources of greenhouse gases (Gerber et al., 2013). Mobility is a highly adaptive strategy regarding av ailability and annual variability of forage resources, opportunity for increasing flock size and thus labor productivity . The present study aims at estimating enteric methane (CH 4 ) of French Mediterranean sheep farming systems, especially the use of diversified pastoral feed resources, using a simulating model (Diversity of feed REsources and Enteric Methane emissions, DREEM). Four case studies were chosen regardi ng contrasting farming and mobility in the French Mediterranean systems, from low (sedentary) to hi gh (permanently transhuming) farming systems. First results showed a negative relationship between mobility and enteric CH 4 emissions as far as contrasting farming systems are concerned. At individual level, enteric CH 4 emissions from sedentary system ewes were the highest. This is mainly due to feed intake and feed characteristics. However, flock management, which depends on land use and owners hip, questions these results. This methodology requires improvements regarding feeding char acterisation and a larger farming systems sampling. Finally, these results have to be analysed at a global level by estima ting total GHG emissions of the farm, according to economic and LCA models of farming systems (Benoit et al., 2010)

Evaluating livestock mobility as a strategy for climate change mitigation: combining models to address the specificities of pastoral systems

Pastoral farming systems have always adapted to the seasonal availability of forage resources and climate variability by moving animals. However, the role of animal mobility as a possible mitigating strategy in response to climate change has not been clearly documented. To understand this role, we investigated (i) the major methodological challenges linked to the diversity of grazing areas and other forage resources exploited by these systems and enteric emissions of methane; (ii) the impacts of grazing practices (carbon sequestration/emission) on soil and biomass carbon fluxes. We developed an approach based on two existing models (Ostral: Outil de Simulation du TRoupeau ovin ALlaitant and Casa: Carnegie Ames Stanford Approach) that we adapted and used in combination. This approach was applied to three French Mediterranean sheep and crop farming systems with different degrees of flock mobility (sedentary, single transhumance and double transhumance). The preliminary results produced by the whole farm model OSTRAL showed that two systems (sedentary and double transhumance) causing low carbon emissions. In the sedentary system, higher animal productivity offsets the increase in GHG emissions (in CO2 eq) caused by feed production. In the pastoral system, grazing reduced total GHG emissions (in CO2 eq). The CASA model proved to be useful to simulate the carbon balance under dynamic land cover in natural environments, whether used for grazing or not. This model can help assess the impact of grazing practices and carbon fluxes in systems linked to natural environments. The results of the first application showed that seasonal mobility of livestock increases the contribution of rangeland to feeding systems and improves the non-renewable energy balance of the system. It is thus extremely important to include the specificities of animals grazing in rangelands outside the structural limits of the farm when evaluating GHG emissions

Combined modelling tools to evaluate the impact of flock mobility on ghg emissions in sheep farms

International audiencePastoral farming systems have always adapted to the seasonal availability of forage resources by moving flocks. However, the role of flock mobility as a possible mitigating strategy in response to climate change has not been clearly documented. Thus, we investigated: (1) the major methodological challenges linked to the diversity of forage resources used and corresponding methane enteric emissions; (2) the functioning of farming systems based on different combinations of natural resources and their GHG emissions; (3) the impacts of grazing practices on soil and biomass carbon flows. We developed an approach combining two existing models (OSTRAL and CASA) enhanced and adapted. This approach was applied to three French Mediterranean sheep farming systems with different degrees of flock mobility: sedentary (SED), single transhumance (ST) and double transhumance (DT). Results produced by OSTRAL whole farm model showed that, considering GHG emissions, DT is the most efficient system with 27,6 kg CO2Eq/kc carcass weight vs 35.1 and 30.9 respectively for ST and SED. Indeed, low inputs and high carcass weight compensate the lower ewe productivity. Non-renewable energy consumption (LCA approach) is very low for DT as there is nearly no inputs: 31 MJ/kg CW vs 82(ST) and 76 (SED). The CASA model allows us to simulate long term carbon balance scenarios according to land cover dynamics in natural environments relatively to grazing intensities, and so to evaluate contribution of livestock to carbon regulations. Combining both models shows that changing the way of using natural grazed areas, and so their capacity of carbon sequestration, could drastically modify hierarchies between these systems concerning mitigation potential. This underlines the potential interest of coupling tools to enlarge the range of analysis

Contribution aux bilans d’émissions de GES de la mobilité de troupeaux ovin sur parcours méditerranéen

International audienceAdaptation of farming activities and contribution to mitigation are at stake. In sheep livestock farming in the Mediterranean, increase in flock mobility and use of rangelands are adaptations of the last decades. We simulate three systems significant of these dynamics (sedentary S, single transhumance ST, double transhumance DT) while combining estimates concerning methane emissions, carbon sequestration on rangelands and whole farm model simulations. Mobility and rangeland food contribution, limiting inputs, contribute in defining efficient systems. GEG emissions are respectively estimated at 33.86; 39.45; 33.75 kg CO2 eq/ kg CW Coupling estimates of direct emissions and simulation of relationship between grazing and carbon cycle in rangelands allows an estimation of mitigation potential of the activity. On methodology, these results underline the interest in considering both emission and sequestrations and the necessity in coupling the analysis of farming systems functioning and ecological systems of grazed areas.L’adaptation des activités d’élevage et l’atténuation du changement climatique sont des enjeux. En élevage ovin méditerranéen, l’accroissement de la mobilité des troupeaux et de l’usage des parcours sont des adaptations des dernières décennies. Nous simulons trois systèmes archétypiques de ces dynamiques (sédentaire [S], simple transhumant [ST], double transhumant [DT]) en combinant estimations des émissions de méthane entérique, séquestration du carbone des parcours et fonctionnement de l’élevage. La mobilité et la contribution de ressources pâturées sur milieux naturels, en limitant les intrants, permet de développer des systèmes efficients. Les émissions de GES sont estimées respectivement à 33.86 ; 39.45 ; 33.75 eq. kg CO2/kg carcasse pour les systèmes Sed, ST, DT. Le couplage entre des simulations d’émissions directes et de l’incidence du pâturage sur le cycle du carbone permet d’évaluer le potentiel d’atténuation de l’activité. Sur un plan méthodologique, ces premiers résultats soulignent l’intérêt de considérer conjointement émission et séquestration, la nécessité de coupler plus étroitement l’analyse des fonctionnements des systèmes d’élevage et des systèmes écologiques des milieux pâturés

La mobilité des systèmes d’élevage ovins utilisateurs d’une grande variété de ressources pâturées en Provence : impacts sur le bilan énergétique et les émissions de méthane

La mobilité des systèmes d’élevage ovins utilisateurs d’une grande variété de ressources pâturées en Provence : impacts sur le bilan énergétique et les émissions de méthane. Réseau prairies – Symposium 201

Rhizome filling seems to be triggered by climatic events in Miscanthus x giganteus

International audienc