Location: Dairy Forage ResearchTitle: Tannin extracts abate ammonia emissions from dairy barn floors Author
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2011
Publication Date: 3/24/2011
Publication URL: http://handle.nal.usda.gov/10113/53752
Citation: Powell, J.M., Aguerre, M.J., Wattiaux, M.A. 2011. Tannin extracts abate ammonia emissions from dairy barn floors. Journal of Environmental Quality. 40:3:907-914. Interpretive Summary: Dairy cows excrete large amounts of urine, so barns are thought to emit large amounts of ammonia which can adversely impact the health of humans and natural ecosystems. We conducted a study to determine if feeding more tannin and less crude protein to dairy cows would reduce urine excretion and ammonia emissions from dairy barns. Study results show that relative reductions in ammonia emission due to tannin feeding were greatest at the low crude protein diet due to lower amounts of urine nitrogen excreted and therefore applied. Tannins reduced ammonia emissions by 30% at the low crude protein diet and 16% at the high crude protein diet. The application of tannin directly to the barn floor also decreased ammonia emission by 20%. Although results of these laboratory studies are encouraging, larger scale studies are required to ascertain effectiveness of tannin extracts in abating ammonia loss from commercial dairy barn floors.
Technical Abstract: Feeding more tannin and less crude protein (CP) to dairy cows may have compound positive impacts on reducing NH3 emissions from dairy barns. Mixtures of feces-urine from lactating Holstein dairy cows (Bos taurus) fed four levels (g kg-1) of dietary tannin extract: 0 (0T), 4.5 (low tannin, LT), 9.0 (medium tannin, MT) and 18.0 (high tannin, HT); each fed at two levels (g kg-1) of dietary CP: 155 (low CP, LCP) and 168 (high CP, HCP) were applied to lab-scale ventilated chambers. Emissions were measured 1, 3, 6, 12, 24, 36 and 48h after treatment applications. Relative reductions in NH3 emission due to tannin feeding tended to be greater at the LCP diet due to lower amounts of urine N applied. At 24-h for LCP, average NH3 emission from LT, MT and HT was 33.3% less than 0T. At 24-h for the HCP diet, average NH3 emission from LT and MT was 20.4% less than 0T, and NH3 emission from HT was 37.0% less than 0T. Average cumulative NH3 loss from LCP-LT and LCP-HT was 30.6% less than 0T, and average cumulative NH3 loss from HCP-LT and HCP-HT was 16.3% less than 0T. Feeding tannin decreased urease activity in feces resulting in 11.5% reduction in cumulative NH3 loss. The application of tannin directly to barn floor (rather than feeding) decreased NH3 emissions resulting in a 20.3% reduction in cumulative NH3 loss. Although study results are encouraging, larger scale trials are required to ascertain effectiveness of tannin extracts in abating NH3 loss from dairy barn floors.