Greenhouse gas and ammonia emissions from stored manure from beef cattle supplemented 3-nitrooxypropanol and monensin to reduce enteric methane emissions
Owens, J.L., Thomas, B.W., Stoeckli, J.L., Beauchemin, K.A., McAllister, T.A., Larney, F.J., Hao, X. (2020). Greenhouse gas and ammonia emissions from stored manure from beef cattle supplemented 3-nitrooxypropanol and monensin to reduce enteric methane emissions. Scientific Reports, [online] 10(1), http://dx.doi.org/10.1038/s41598-020-75236-w
Plain language summary
3-Nitrooxypropanol (3-NOP) is an investigative material that can reduce enteric methane emissions from ruminants such as beef cattle.
It is unknown whether greenhouse gas (GHG) emissions from manure from cattle supplemented 3-NOP differ from those produced from conventional manure. If so, then the reductions in GHGs from reduced rumen CH4 production that are achieved through dietary supplementation of 3-NOP may be shifted “down stream” to manure handling.
In this study, we composted and stockpiled manure from cattle that had received supplements of 3-NOP, with and without monensin, a drug that is commonly provided to North American beef cattle to improve feed digestibility.
The manure was composted or stockpiled for a total of 202 days. The stockpiled manure was left static for the duration of the trial and the composted manure was turned three times. Greenhouse gases (carbon dioxide, methane, and nitrous oxide) along with ammonia emissions were measured during manure storage.
We also estimated dry matter, total carbon, and total nitrogen mass balances as a way to determine whether there were differences in decomposition between conventional and 3-NOP manure when composted or stockpiled.
The investigative material 3-nitrooxypropanol (3-NOP) can reduce enteric methane emissions from beef cattle. North American beef cattle are often supplemented the drug monensin to improve feed digestibility. Residual and confounding effects of these additives on manure greenhouse gas (GHG) emissions are unknown. This research tested whether manure carbon and nitrogen, and GHG and ammonia emissions, differed from cattle fed a typical finishing diet and 3-NOP [125–200 mg kg−1 dry matter (DM) feed], or both 3-NOP (125–200 mg kg−1 DM) and monensin (33 mg kg−1 DM) together, compared to a control (no supplements) when manure was stockpiled or composted for 202 days. Consistent with other studies, cumulative GHGs (except nitrous oxide) and ammonia emissions were higher from composted compared to stockpiled manure (all P < 0.01). Dry matter, total carbon and total nitrogen mass balance estimates, and cumulative GHG and ammonia emissions, from stored manure were not affected by 3-NOP or monensin. During the current experiment, supplementing beef cattle with 3-NOP did not significantly affect manure GHG or NH3 emissions during storage under the tested management conditions, suggesting supplementing cattle with 3-NOP does not have residual effects on manure decomposition as estimated using total carbon and nitrogen losses and GHG emissions.