Cows' carbon hoofprint is smaller than thought

October 3, 2013 by Stacey Shackford & Rebecca Harrison

( —The carbon hoofprint of dairy cows may be smaller than previously thought, report Cornell researchers.

Cows and other ruminants are the ultimate recyclers, and they deserve some credit for helping the environment while providing high-quality nutrients through their dairy products, says Michael Van Amburgh, professor of animal science.

Addressing a Sept. 12 food policy symposium hosted by International Programs in the College of Agriculture and Life Sciences, Van Amburgh explained that cows are often fed byproducts from human food and biofuel production processes that would be costly to dispose of otherwise.

In fact, the alternative – incineration – directly contributes to environmental degradation, so cows actually help reduce the impact of the human and make that food supply affordable.

An example, he said, is the California almond industry that relies on cattle to consume four billion pounds of shelled almond hulls each year.

In addition, cows make use of land not suitable for food crops. And thanks to complex modeling – some of which was developed at Cornell – dairy farmers can precisely calculate the carbon output of their and adjust their diets accordingly.

"We can't change the cow's methane production by much, but we can change efficiencies, milk per unit of gas," Van Amburgh said.

Animal products provide an important source of nutrients, especially for children and older adults, that should not be discounted, he said. Even if we switch to a more plant-based diet, we would need an environmentally sound system of disposal for matter not consumed.

Van Amburgh pointed out that every food has an environmental impact, and that we should consider how many nutrients we get in return for the emissions generated in its production.

For example, a 2010 Swedish study calculated the nutrient density – the nutrient content and number of nutrients per serving – of several beverages in relation to the associated with their production, manufacturing, packaging and transportation. Milk rated very highly, with a high nutrient density index per equivalent carbon emission of 53.8 per 99 grams greenhouse gas emission. Soy drinks and red wine, by comparison, have a nutrient density index of 7.6 per 30 grams and 1.2 per 204 grams of emissions, respectively.

Van Amburgh has also found in a study (not yet published) that carbon dioxide and methane emissions from byproducts included in animal feed are considerably lower when fed to dairy cattle than when incinerated.

Byproducts most often used in the American dairy industry include distillers' grains from ethanol production, citrus pulp from juice production, almond and soybean hulls, soybean meal, cottonseed, extracted canola meal and even baked goods and candy.

Their inclusion in not only helps the environment, but can boost and enhance yield and provide an economic opportunity for the byproducts that in many cases greatly reduces the cost of to the consumer, Van Amburgh said.

"Because of the microbial fermentation digestion process that occurs in the cow's rumen, the are digested in a manner that can positively enhance the nutrient supply," he said. "For example, candy byproduct provides sugar and the end product of the fermentation produces the substrate necessary for milk sugar production, so fed in moderation, candy can enhance milk yield with no ill effects on the composition or quality."

Explore further: Traces of cow’s methane emissions in the milk

Related Stories

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 ...

Wine dregs shown to improve cows' milk

December 8, 2011

Feeding dairy cows the stems, seeds and skins from wine grapes boosts milk production and dramatically cuts the animal's methane emissions, Australian researched published Thursday shows.

Recommended for you

Tracking Antarctic adaptations in diatoms

January 16, 2017

Diatoms are a common type of photosynthetic microorganism, found in many environments from marine to soil; in the oceans, they are responsible for more than a third of the global ocean carbon captured during photosynthesis. ...

Study tracks 'memory' of soil moisture

January 16, 2017

The top 2 inches of topsoil on all of Earth's landmasses contains an infinitesimal fraction of the planet's water—less than one-thousandth of a percent. Yet because of its position at the interface between the land and ...

How the darkness and the cold killed the dinosaurs

January 16, 2017

66 million years ago, the sudden extinction of the dinosaurs started the ascent of the mammals, ultimately resulting in humankind's reign on Earth. Climate scientists have now reconstructed how tiny droplets of sulfuric acid ...

Soil pores, carbon stores, and breathing microbes

January 16, 2017

Researchers at the Pacific Northwest National Laboratory (PNNL) recently studied how moisture influences soil heterotrophic respiration. That's the breathing-like process by which microbes convert dead organic carbon in the ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.