Research reveals cow feed as air pollutant
Researchers and other scientists who have assiduously studied cow manure as an air pollutant might have focused their attention on the wrong end of the cow.
Dairy animal feed, especially corn silage, is now being tagged as a significant cause of ozone creation, the major contributor to air pollution, especially in the San Joaquin Valley. Air quality in the valley, home to one of the highest concentrations of dairy animals in the world, has been identified for years as substandard, even dangerous.
The report from the Department of Civil and Environmental Engineering at the University of California, Davis, reveals that certain animal feeds cause just as much ozone pollution before they are eaten as they do when they are excreted.
Most of the views we see of feed for cattle feature the happy cows munching contentedly on rations spread before them. But feed, especially silage, is stored for months at most dairies. It is often contained in trenches that serve as silos or large plastic bags big enough to drive a pickup through, stretching a hundred feet or more along the ground.
The daily chore of removing feed from the bags releases serious amounts of ozone-causing gasses and chemicals stored in the steaming contents. The odors excite the cows' appetites, but it has been discovered recently that the aroma contributes significantly to smog and other forms of air pollution.
The worst of the seven feed combinations that were evaluated in the Davis experiment is corn silage. A measured amount of it taken from a trench silo was shown to produce more ozone-forming gasses than a light-duty pickup. Alfalfa silage was the next worst, producing slightly less gasses than the pickup.
Almond hulls and almond shells, which were evaluated along with five other common dairy feed mixes, produced the lowest amount of the offending gasses. One or both are usually part of the other popular feed combinations that were studied.
The seven-person research team was directed by Professor Mike Kleeman of the Department of Civil and Environmental Engineering. The team enjoyed the assistance of the Crocker Nuclear Laboratory and the Department of Animal Science at Davis
Measuring the offending reactive organic gasses (ROG) was done with the help of a transportable smog chamber. Ethanol and other alcohol species accounted for more than 50 percent of the ozone formation for most types of feed.
The researchers' report said aldehydes were also significant contributors for cereal silage, high-moisture ground corn and total mixed ration.
"Ozone production calculations based on feed consumption rates, ROG emissions rates and OFP (ozone formation potential) predict that animal feed emissions dominate the ROG contributions to ozone formation in the San Joaquin Valley," the report said.
It also recommends that further study of the effect of the feeds on air pollution be conducted. That is entirely possible since the initial research was supported by the San Joaquin Valley Air Pollution Control District, a USDA grant and the California Air Resources Board.
A major conclusion of the study was stated this way: "Chamber measurements confirm that animal feed ROG emissions are significantly higher than animal waste emissions, and several of the animal feed ROG compounds have potentially high OFP."
Dairymen have applied volumes of data about the methane output of their animals' waste, and have found positive, nonpolluting ways to capture and contain it to create electrical energy. Perhaps their emphasis needs to move to the other end of the cows.
Meanwhile, California's happy cows just keep smiling as they consume all those ROGs and OFPs contained in that 90-proof bovine moonshine called corn silage.
CONTACT Don Curlee at email@example.com