Abstract. From the information provided by the National Farm Accountancy Data Network (FADN), referred to the sheep orientation for years 1987, 1990, 1994, 1999 and 2002 (added information of the sample of the sheep farms), the structural, economic and productive characteristics of representative meat and milk sheep systems of nine Spanish regions are described. Indices of animal productivity are elaborated (livestock capital), assimilable to the technical efficiency. For the considered regions, the differences in productivity, its evolution during the period 1987-2002 and its possible relationship with some characteristics of farms are analyzed. Considering that the productivity is a long term determinant of standard of living for sheep farmer, we try to advance a hypothesis related to sources of knowledge of this sector and role of technological change.

From the concept of sustainability and the multifunctionality role attributed to the European farming systems, a first approach to the analysis and discussion of the relationship between the labour productivity, as partial indicator of the economic sustainability of the livestock farms and its environmental function was made. A sample of 11 sheep farms that use a Natural Park, representative of four farm groups established in a previous study by means of multivariate statistical analysis, was studied. For each farm, economic results and an indicator of family labour productivity, the relative levels of grazing and the relations between the farms and the market and the agro-sylvopastoral systems were calculated . These results show that there is not a clear relationship between the levels of the indicator of economic sustainability of farms and their environmental function.