Feeding cows natural plant extracts can reduce dairy farm odors and feed costs

Sep 01, 2011

With citizens' groups seeking government regulation of foul-smelling ammonia emissions from large dairy farms, scientists today reported that adding natural plant extracts to cow feed can reduce levels of the gas by one-third while reducing the need to fortify cow feed with expensive protein supplements. They reported here at the 242nd National Meeting & Exposition of the American Chemical Society (ACS).

J. Mark Powell, Ph.D., described the results of three studies undertaken to determine how adding plant substances called "tannins" to cow feed affects the emission of ammonia from dairy barn floors and farm fields fertilized with mixtures of cow manure and urine.

"For , cow urine is the source of the ammonia emission problem," said Powell, who is with the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS). "Dairy cows excrete large amounts of urine, about 3.5 gallons daily for each cow. That's almost 1,300 gallons per year. And there are about 10 million dairy cows in the United States alone. Cows usually are fed a high-protein diet, and they produce various nitrogen compounds when they digest protein. They release the excess nitrogen mainly in their urine, and enzymes convert it into ammonia."

Ammonia has an acrid, eye-tearing odor and has potential adverse health effects on both cows and humans. Citizens' groups several months ago petitioned the U.S. Environmental Protection Agency (EPA) to begin regulating ammonia under the Clean Air Act, intensifying the search for practical, inexpensive ways to reduce emissions of the noxious gas. Besides its pungent odor, ammonia adds to air pollution, forming particles that travel long distances and contribute to environmental issues such as smog, acid rain and nutrient pollution.

The ammonia problem originates with the nitrogen-rich protein in cow feed. Cows' digestive systems are inefficient, and barely one-third of the nitrogen in their feed ends up in milk. The rest exits in urine and feces. The nitrogen in urine is in the form of urea, and enzymes contained in cow manure on the barn floor quickly convert it into ammonia gas.

Tannins apparently reduce urea production by allowing more protein to escape digestion in the stomach and enter the cow's intestines, where it's used to produce milk protein.

Powell began investigating tannins in animal feed 20 years ago in West African communities where he lived and worked. Tannin-rich shrubs were grown as windbreaks to reduce soil erosion and to feed livestock. Tannins also are a key part of the diets of cattle, sheep and goats in tropical areas where vegetation tends to be naturally higher in the astringent plant chemicals. However, tannins have attracted relatively little attention elsewhere, Powell said.

He hopes the addition of tannins to animal feed will become much more widespread in light of the findings about their potential for curbing . The tannin extracts used in the studies are already approved for animal feed and would cost only a few cents a day, he said. Tannins are perhaps best known for their use in tanning leather, and the quebracho and chestnut trees are sources for both leather tanning and cattle feed. Powell said that it may be possible to produce synthetic tannins at a lower cost.

Next on Powell's agenda is research to determine whether tannins also can reduce emissions of methane gas — a potent greenhouse gas involved in global warming — from cattle production. About 25 percent of methane emissions in the United States are from enteric fermentation (mostly belches) of domestic cattle.

Explore further: How to prevent organic food fraud

add to favorites email to friend print save as pdf

Related Stories

New strategy aims to reduce agricultural ammonia

May 11, 2011

As concerns about air pollution from large dairies and other concentrated animal feeding operations (CAFOs) continue to mount, scientists are reporting a practice that could cut emissions of an exceptionally abundant agricultural ...

Traces of cow’s methane emissions in the milk

May 27, 2011

Wageningen University researchers in the Netherlands are able to determine cows' methane emissions using the composition of fatty acids in their milk. This opens up the prospect of a method for reducing methane production ...

Digging deep for ways to curb ammonia emissions

Sep 28, 2010

Dairy farmers can greatly reduce ammonia emissions from their production facilities by injecting liquid manure into crop fields below the soil surface, according to research by the U.S. Department of Agriculture (USDA).

Put more nitrogen into milk, not manure

May 28, 2010

The more efficient dairy farmers are in managing nitrogen, the more milk their cows will produce and the less nitrogen will be wasted in manure and urine, according a study by Agricultural Research Service (ARS) scientists ...

Researchers study harmful particulates

Feb 26, 2007

Reducing barnyard emissions is one way to help reduce the harmful effects of tiny atmospheric air particles that can cause severe asthma in children, and lung cancer and heart attacks in some adults.

Recommended for you

Team pioneers strategy for creating new materials

Aug 29, 2014

Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn't always work as expected. To create a new strategy for designing materials, ...

Plug n' Play protein crystals

Aug 29, 2014

Almost a hundred years ago in 1929 Linus Pauling presented the famous Pauling's Rules to describe the principles governing the structure of complex ionic crystals. These rules essentially describe how the ...

Protein glue shows potential for use with biomaterials

Aug 28, 2014

Researchers at the University of Milan in Italy have shown that a synthetic protein called AGMA1 has the potential to promote the adhesion of brain cells in a laboratory setting. This could prove helpful ...

User comments : 0