Effects of oral nitroethane administration on enteric methane emissions and ruminal fermentation in cattle

Methane is a potent greenhouse gas and its release to the atmosphere is widely believed to contribute to global warming. Ruminal enteric CH4 production represents a loss of 2–15% of the animal's gross energy (GE) intake and contributes nearly 20% of US CH4 emissions. Studies have evaluated the CH4 inhibiting potential of select short chain nitrocompounds, such as nitroethane, but results demonstrating their effects on ruminant exhaled CH4 emissions are lacking. Our study determined effects of oral nitroethane administration on CH4 emissions, accumulations of volatile fatty acids (VFA) and on ruminal CH4 producing activity in steers fed a forage based diet containing 8.8MJ/kg of metabolizable energy on a dry matter (DM) basis. Effects of nitroethane administration on ruminal nitroethane reducing activity were also determined. Holstein steers (n=24) of 317±6.5kg body weight (BW) were assigned to 4 treatments that included: 0, 30, 60 and 120mgnitroethane/kgBW/d. Treatments were administered via oral gavage twice daily at 08:00 and 16:00h for 8d. DM intake decreased quadratically as level of nitroethane increased with steers administered 60 and 120mgnitroethane/kgBW consuming 14 and 7% lower DM, respectively, than steers administered 0 or 30mgnitroethane/kgBW. Methane emissions as a proportion of GE intake and ruminal CH4 producing activity both decreased linearly (P