Improving the efficacy of concentrate usage by smallholder dairy farmers in Kenya - Romney, Dannie L.; Wambugu, M.; Kaitho, R.; Biwott, J.; Chege, L.; Omore, Amos O.; Staal, Steven J.; Wanjohi, P.; Njubi, D.; Thorpe, W.R. (Intermediate Technology Development Group, 2005)