WS 3: Adaptive farming systems 8 th European IFSA Symposium, 6 -10 July 2008, Clermont-Ferrand (France) 435 How can farms with beef cattle systems based on permanent pasture cope with extreme climatic years? Results of a study using the whole-farm simulator SEBIEN René Baumont a , Magali Jouven b , Nicolas Deux a , Anne Farruggia a a INRA, Unité de Recherches sur les Herbivores, Saint Genès Champanelle, France; b Supagro, UMR Elevage des Ruminants en Régions Chaudes, Montpellier, France – baumont@clermont.inra.fr Abstract: The farm-scale simulation of grassland production and use allows the farm system to be evaluated for feed self-sufficiency under different management strategies and in different climatic years. We investigated the impact of the frequency of years unfavourable to grassland production, such as the year 2003 that was characterized by a severe spring drought and by heat stress. We used the whole-farm simulation model SEBIEN, which reproduces the steady-state functioning of grassland- based beef suckler systems. The model is based on the interface of animal, vegetation and management sub-models, and was calibrated for suckler farms in the upland areas of the Auvergne region in France. We ran the model with a recent climatic series (1994-2005) and with artificial climatic series consisting of increasing frequencies of unfavourable years (e.g. 2003) or ’normal’ years (e.g. 2000) for grassland production. Simulation results indicated that without changing the management rules, in 2003 the total amount of herbage harvested was reduced by 54% compared to 2000. The grass quality was also markedly reduced in 2003, leading to a dramatic decrease in farm feed self- sufficiency. The frequency of unfavourable climatic years did not affect the average results for 2003 and 2000. Adaptations of the forage system, aimed to cope with frequent climatic incidents as drought and heat stress were tested with the simulation model. Increasing farm area with productive grassland or increasing the productivity of the grassland for the same farm area were found to be efficient to improve feed self-sufficiency. Changing the harvesting system from field-dried hay to earlier cut forage conserved as barn-dried hay or big bale silage, was found to be the most efficient and minimised the loss of harvested herbage to 34% while maintaining grass quality. However, these adaptations have an economic cost and environmental impacts that need to be taken into account. This study highlights the importance of adapting the management rules of the forage system, either tactically or strategically, to cope with extreme climatic events. Keywords: forage system, beef cattle, permanent pasture, drought, climate change, adaptation, simulation Introduction Climate change will probably produce increased frequency of adverse climatic events. A recent example occurred in 2003, when drought and heat stress caused a dramatic decrease in crop and forage yields and, consequently, livestock performance. The impact of such events might be beyond that caused by the normal variability of climatic conditions (Easterling et al., 2007). Beef suckler systems that rely exclusively on permanent pastures such as those found in upland areas of Europe (e.g. Massif Central, France), might be very sensitive to extreme climatic events such as those which occurred in the spring and summer of 2003. The sustainability of such systems depends mainly on their feed self-sufficiency (Lherm and Benoit, 2003). Given the constraints of a continental climate, the production of herbage is concentrated in spring and summer. Thus, the animal production cycle and the forage system are managed to exploit herbage growth for grazing and also for the harvest of hay (Figure 1). During the long (5 to 6 months) winter period, the herd is housed and fed with conserved forage. The amount and quality of the hay harvested should be sufficient to feed the cows during late pregnancy and early lactation, which usually occur in winter. A drought in summer and spring is very harmful to these systems, where farmers depend on high yields for the first hay cut and are not used to sparing standing forage for grazing in summer. We investigated the impact of climatic events on feed self-sufficiency in a beef suckler system typical of the Massif Central. We used the whole-farm simulation model SEBIEN (Jouven and Baumont, 2008) which reproduces the steady-state functioning of grassland-based suckler systems. We