Enteric methane emitted by ruminants is a nutritional inefficiency that contributes to global warming. Feeding substantial quantities of wheat grain to dairy cows has been reported to decrease enteric methane emissions compared with other feeds. Feeding methane mitigating agents such as nitrate, fat and 3-nitrooxypropanol (3-NOP) to ruminants have also been reported to decrease enteric methane emissions. This research involved three in vitro experiments that examined the combined effect of wheat grain with nitrate, fat or 3-NOP on in vitro methane mitigation. In each of the experiments, wheat grain or corn grain were incubated in combination with one of the three methane mitigating agents (nitrate, fat or 3-NOP). The fermentation of wheat grain produced 22% less methane than the fermentation of corn grain. All three methane mitigating agents decreased in vitro methane production and methane production expressed per gram of dry matter degraded. The addition of nitrate, fat and 3-NOP decreased in vitro methane production by 21, 19 and 44% respectively. The methane mitigating effect of wheat grain in combination with nitrate, fat or 3-NOP was greater than the individual effects of wheat grain, nitrate, fat or 3-NOP. The feeding of the combination of wheat grain with nitrate, fat or 3-NOP to ruminants may be effective strategies for decreasing their enteric methane emissions.