A method (400), and systems (100) implementing such method, for reducing methane emissions by ruminants. The method (400) includes providing (405) a feed dispenser (120) for feeding ruminants one or more nutrient supplements (126), and the feed dispenser (120) includes a gas analyzer (116) proximate to where the ruminant places its head. The method (400) includes determining (420) a particular ruminant (204) has accessed the feed dispenser (112, 120) such as by reading an identifier from an RFID ear tag (208) and operating (444) the feed dispenser (120) to provide a ration of methane-controlling nutrient supplement (126). The method (400) includes using the gas analyzer (116) to determine (470, 476) levels of carbon dioxide and methane (210, 214) and operating (490) a data analyzing station to determine a ratio of methane to carbon dioxide and modify the type or amount of nutrient supplement (126) for the ruminant (204) for a next feeding to control methane production or achieve an animal production goal, such as by selectively operating a hopper (122) with two or more supplements compartments.
