Sun X. Z., Hoskin S. O., Zhang G. G., Molano G., Muetzel S., Pinares-Patiño C. S., Clark H., Pacheco, D. 2012. Sheep fed forage chicory (Cichorium intybus) or perennial ryegrass (Lolium perenne) have similar methane emissions. Animal Feed Science and Technology, 172, 217-225. 
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