|Todd, Richard - Rick|
Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2012
Publication Date: N/A
Interpretive Summary: Too much ammonia in the environment can negatively affect air quality and ecosystems. Beef cattle feedyards are a significant source of ammonia lost to the atmosphere. Ammonia loss is sensitive to temperature, with summer loss twice that of winter. Ammonia loss is also sensitive to the crude protein in cattle diets, and increases as diet crude protein increases. Averaged over a year, from 80 to 130 grams of ammonia nitrogen can be lost each day for each head of cattle in a feedyard; that represents about half the nitrogen fed to cattle. Adding substances that keep ammonia in manure rather than going into the atmosphere can effectively control ammonia loss, but these substances are expensive and often hard to apply. Feeding just the right amount of crude protein in cattle diets is probably the best way to control ammonia loss. But new feeds that can increase crude protein in diets, like distillers grains, could make that more difficult.
Technical Abstract: Beef cattle feedyards in the U.S. annually emit about 400 Gg of ammonia-N to the atmosphere. We summarize seven years of field and laboratory research on ammonia emissions from beef cattle feedyards on the Southern High Plains. Daily and annual ammonia emission patterns depended strongly on temperature, with summer emissions consistently twice those during winter. Ammonia emissions were also sensitive to crude protein content of cattle diets. Ammonia emissions increased from 25-50% when crude protein increased above requirements of cattle. Annually, ammonia emissions averaged from 80 to 130 g NH3-N head-1 d**1, which was 52 to 59% of fed N. We tested strategies to reduce ammonia emission including reducing N intake, urease inhibitors, and ammonium binders. Reducing N intake was the most economically and operationally feasible strategy, but a feeding environment that includes higher protein ethanol byproducts like distillers grains challenges efforts to reduce ammonia emissions.