Do the effects of dietary greenhouse gas inhibitors persist in beef cattle manure during composting and stockpiling?
Jen Owens, Xiying Hao, Ben W. Thomas, Jessica L. Stoeckli, Francis J. Larney, Karen A. Beauchemin, Tim A. McAllister. 2018. Do the effects of dietary greenhouse gas inhibitors persist in beef cattle manure during composting and stockpiling? 2018 Joint Meeting of the CGU-CSSS-CIG-CSAFM-ESSSA. June 10-14, 2018. Niagara Falls, ON. Canada.
Plain language summary
The inhibitory effects of 3-nitrooxypropanol to methane occur only in cattle rumen, and do not persist in manure.
Dietary supplements 3-nitrooxypropanol and monensin may reduce methane production in ruminants. There has been little research into whether the effects of these inhibitors persist in manure. If they affect manure composition or remain biologically active, they may alter greenhouse gas emissions (GHG; i.e., CO2, CH4, N2O) and NH3 from manure. Furthermore, emission responses may vary depending on manure management practices. The objectives of this research were to test whether manure from beef cattle receiving 3-nitrooxypropanol or monensin in their diets had lower GHG emissions than that from control cattle that did not receive these additives. Emissions were also assessed in manure that was composted or stockpiled in the semiarid climate of southern Alberta. Manure was obtained from beef cattle fed a typical barley grain-based finishing diet with no additives (control), 3-nitrooxypropanol (200 mg kg-1 DM) alone, or 3-nitrooxypropanol (200 mg kg-1 DM) and monensin (33 mg kg-1 DM). Manure was combined within treatments and randomly assigned to either three replicate compost windrows or stockpiles. Compost was turned once a month for the first three months of the trial, and for the following four months, both the compost and stockpile were left in storage. Methane, CO2, N2O and NH3 fluxes were measured once or twice a week for three months, and once a month thereafter. Carbon dioxide, CH4 and NH3 emissions were lower from the stockpile than from compost, with no difference in N2O emissions between storage methods. The results showed no persistent effects of 3-nitrooxypropanol or monensin on CH4, CO2, N2O and NH3 emissions from manure. These results suggest the inhibitory effects of 3-nitrooxypropanol and monensin occur only in the rumen, and do not persist in manure.