Water footprint of milk production systems in semi-arid plains of North Africa

Water resources are becoming scarce and must be preserved. The significant use of water is linked to agriculture in general and to livestock in particular. Very little research in semi-arid regions has been devoted to assessing the contribution of ruminants to water scarcity. This contribution explores the relationships between dairy farming and the various water resources available in an ecosystem with climatic constraints. To meet future food demand while sustainably managing the available land and water resources, dairy farm systems in semi-arid regions must adapt in response to climate and socio-economic change. In this study, we focus on the south Mediterranean region to analyze the key factors influencing water productivity in dairy farming, especially in context characterized by water scarcity. In order to characterize the relationship between dairy cattle breeding and water resources, a monitoring of 40 dairy cattle stables has been carried out in a semi-arid region. The technical and economic parameters of each farm were evaluated: the use of water according to their origins to the production of fodder by source, the contribution of virtual water off the farm, the total fodder biomass, feeding system practiced on the farms and the performances achieved. Analysis of the data indicates that productivity of fodder in dry matter differ between the two systems with values of the order of 12520 to 17188 kg/ha (p<0.05) respectively for type extensive and intensive systems. The milk yield per cow did not exceed an average value of 3680 kg (rang 3240 to 4120 kg. The mean gross margin per kilogram of milk was low, not exceeding 0.13?. A significant effect (p<0.05) of the value of the water footprint between the two dairy farm systems with an average of around 2.05m3/kg of milk (range 1.96 to 2.15 respectively for intensive and extensive farms). The contribution of rainfall is estimated at 57% and the rest is represented by the participation of irrigation and virtual water with 18% and 25% respectively. Necessary actions must be taken along the milk production process in order to improve the productivity of water for forage production and the milk which depends in large part on annual rainfall and to a lesser extent on groundwater.