Livestock farming has recently come under close scrutiny, in response especially to environmental issues. Farmers are encouraged to redesign their livestock farming systems in depth to improve their sustainability. Assuming that modelling can be a relevant tool to address such systemic changes, we sought to answer the following question: 'How can livestock farming systems be modelled to help farmers redesign their whole farming systems?' To this end, we made a literature review of the models of livestock farming systems published from 2000 to mid-2009 (n 5 79). We used an analysis grid based on three considerations: (i) system definition, (ii) the intended use of the model and (iii) the way in which farmers' decision-making processes were represented and how agricultural experts and farmers were involved in the modelling processes. Consistent rationales in approaches to supporting changes in livestock farming were identified in three different groups of models, covering 83% of the whole set. These could be defined according to (i) the way in which farmers' decisions were represented and (ii) the model's type of contribution to supporting changes. The first type gathered models that dynamically simulated the system according to different management options; the farmers' decision-making processes are assumed to consist in choosing certain values for management factors. Such models allow long-term simulations and endorse different disciplinary viewpoints, but the farmers are weakly involved in their design. Models of the second type can indicate the best combination of farm activities under given constraints, provided the farmers' objectives are profit maximisation. However, when used to support redesigning processes, they address neither how to implement the optimal solution nor its long-term consequences. Models of the third type enable users to dynamically simulate different options for the farming system, the management of which is assumed to be planned according to the farmers' general objectives. Although more comprehensive, these models do not easily integrate different disciplinary viewpoints and different subsystems, which limits their usefulness as support tools for redesigning processes. Finally, we concluded about what specific requirements should be for modelling approaches if farmers were to be supported in redesigning their whole livestock farming systems using models.Keywords: livestock farming systems, modelling, support tools, innovative process, redesign ImplicationsThis review analyses the strengths and weaknesses of published models of livestock farming systems to support farmers in redesigning their whole systems. It is a first step towards building more efficient tools to help farmers to switch towards more sustainable livestock farming systems. IntroductionLivestock farming has recently come under close scrutiny, in response especially to environmental issues (Steinfeld et al., 2006). There is increasing societal pressure for more sustainable livestock practices prompting, for example, the E...

To improve sustainability, farmers may want toredesign their livestock farming systems in depth. Systemicmodelling has proved an efficient tool to study complexissues regarding farming systems, but it remains inefficientto support farmers in their system redesign processes. Thispaper describes and discusses a novel method to modellivestock farming systems with groups of farmers to helpthem redesign their own systems. Modelling livestock farmingsystems at the farm scale with farmer groups is anoriginal approach in livestock farming system modelling.Following a constructivist approach, our method involvesworking with farmers already involved in redesign processesand building causal maps according to their own representations,without using models previously created byscientists. Applying the method, we built two causal mapsof livestock farming system operation, each one built with agroup of five farmers including both those converting andconverted to organic farming. Converting to organic farmingwas considered as one example of a redesign process.On the basis of a subjective assessment by both the participatingfarmers and researchers, and an analysis of mapstructures, we assessed the method’s strengths and weaknesses.We considered that one of its main advantages lay inits collective dimension: sharing, comparing and questioninginterested the participating farmers greatly; however, itrequires good facilitation skills and suitable group composition.Furthermore, the formalising process identified, forexample, vicious circles in system operation, which madethe farmers think about solutions for breaking them. Finally,analysis of map structures identified similarities and differencesbetween the two groups that were discussed with bothof them during a final workshop; this activity continuedfarmers’ self-reflection about their systems, which may helplead to innovative and more sustainable livestock farmingsystems