Silivong P, Preston T R and Man N V 2012: Effect of supplements of potassium nitrate or urea as sources of NPN on methane production in an in vitro system using molasses and Paper mulberry or Muntingia foliages as the substrate. Livestock Research for Rural Development. Volume 24, Article #69. Retrieved , from http://www.lrrd.org/lrrd24/4/sili24069.htm