System prototyping and impact assessment for sustainable alternatives in mixed farming systems in high potential areas of eastern Africa - Waithaka, M.M.; Thornton, Philip K.; Herrero, Mario; Shepherd, Keith D.; Stoorvogel, J.J.; Salasya, B.; Ndiwa, Nicholas N.; Bekele, N.; Croucher, M.; Karanja, S.; Booltink, H.W.G. (International Livestock Research Institute, 2005)