Potential for reducing on-farm greenhouse gas and ammonia emissions from dairy cows with prolonged diet alterations

Authors: DUVAL, BENJAMIN - University Of Wisconsin; AGUERRE, MATIAS - University Of Wisconsin; WATTIAUX, MICHEL - University Of Wisconsin; Vadas, Peter; Powell, Joseph

Submitted to: Journal of Water Air and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2016
Publication Date: 8/13/2016
Publication URL: http://handle.nal.usda.gov/10113/5483264
Citation: Duval, B.D., Aguerre, M., Wattiaux, M., Vadas, P.A., Powell, J.M. 2016. Potential for reducing on-farm greenhouse gas and ammonia emissions from dairy cows with prolonged diet alterations. Journal Of Water Air And Soil Pollution. 227:329.

Interpretive Summary: Animal agriculture contributes to global greenhouse gaseous emissions. Dairy cows are responsible for methane emissions, and nitrous oxide and ammonia are emitted from their manure. We explored if the long-term addition of tannins to dairy cow diets can reduce greenhouse gas emissions. We measured greenhouse gas emissions from cows at the beginning of the experiment and 45 days and 90 days after feeding cows diets with tannins or without tannins. On a per-cow basis, feeding tannins lowered methane emissions by 56g per cow per day at a lower tannin concentration (0.45% of dietary dry matter), and by 48g at a higher concentration (1.8% of dietary dry matter). When calculated based on how much milk cows produced, the high-tannin diet lowered the emissions of methane (33%), ammonia (23%), and nitrous oxide (70%) at the end of the experiment, with no significant loss in milk production. These results strengthen the case that relatively low concentrations of tannins in diets help reduce cow methane production as well as nitrogen gas losses from manure. The effect of feeding tannins to cows lasts over time in the lactation cycle, making this a potential long-term strategy for improving the environmental footprint of milk production.

Technical Abstract: Animal agriculture significantly contributes to gaseous emissions that are implicated in global climate change and local environmental problems. Dairy cows specifically are responsible for enteric methane (CH4) emissions, and produce nitrous oxide (N2O) and ammonia (NH3) emissions from manure. Here, we explore the effects of long-term addition of condensed and hydrolysable tannins to dairy cow diets as a means for greenhouse gas abatement. While previous studies have demonstrated that tannins in cow diets reduce methane and ammonia efflux, none have done so over an extended (>1 month) time period. Using a modified barn, CH4, N2O and NH3 flux were measured at the onset of the experiment, and 45 days and 90 days after feeding groups of lactating dairy cows a control diet, or two levels of tannin extract 0.45% and 1.8% of dietary dry matter. On a per-cow basis, diet alteration lowered CH4 emissions by 56g/cow/day at the lower tannin concentration, and by 48 g/cow/day at the higher concentration. Diet additions resulted in lower CH4 (33%), NH3 (23%) and N2O (70%) milk corrected emissions in the high tannin treatment compared to the control at the end of the experiment, with no significant loss in milk production. These results bolster the case that relatively low concentrations of tannin additions reduce enteric ruminant CH4 production as well as gaseous N losses from manure. Furthermore, the effect of tannin additions to cow diets persists over time through the lactation cycle, making this a potential long-term strategy for improving the environmental footprint of milk production.