Cows contribute less pollution than once thought
By Dairy Herd news source
| Monday, January 31, 2005
According to a study released last week by the University of California-Davis, dairy cows produce only half the amount of ozone-forming gases that researchers had previously thought.
Frank Mitloehner, air-quality management specialist at the UC Davis, reported that dairy cows and their waste contribute about 6.4 pounds of volatile organic compounds per year — half the previous estimate of 12.8 pounds. The 12.8-pound figure was, by most accounts, based on a faulty science. Back in 1978, a consultant made an erroneous assumption based on a study that was done 40 years prior to that, giving false currency to the 12.8-pound number.
Volatile organic compounds cause ozone or smog to form in the atmosphere. Smog is a big health concern in California's central valley.
Another surprising conclusion from Mitloehner's study: Most of a dairy cow's contribution to smog comes not from her manure, but from her belching. That is very significant, because strategies aimed at capping or aerating manure-storage basins, such as lagoons, may prove less important than feeding or managing a cow correctly.
In a previous trial, Mitloehner found that switching from a 20-percent crude protein ration to a 14-percent protein ration reduced ammonia emissions from cows significantly.
He also has found that certain bedding types, such as rice straw, can help control ammonia and dust emissions.
