Thim Sokha, Preston T R and  Khieu Borin 2008 Effect of different protein levels derived from mixtures of water spinach and fresh sweet potato vines in basal diets of broken rice or cassava root meal and rice bran for growing pigs. Proceedings MEKARN Regional Conference 2007: Matching Livestock Systems with Available Resources (Editors: Reg Preston and Brian Ogle), Halong Bay, Vietnam, 25-28 November 2007 http://www.mekarn.org/prohan/sokh.htm