Dairy Farming: Environmental Impact, Ethics, and Industry Outlook

How much does dairy farming contribute to global warming?

Dairy farm cows indoor in the shed
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Dairy farming is the practice of raising and breeding livestock to produce milk for human consumption. While the industry isn't going away any time soon, plant-based milk alternatives such as soy, almond, and oat milk have created a competitive market, driving down the rate of cow’s milk consumption in recent years. Given the dairy industry's tremendous land and water use and the substantial amount of methane produced from cows, this might be considered a gradual environmental win.

How environmentally taxing is dairy farming? Here, we review the impacts and ethics of this sector of agriculture, the competition between small and large dairy farms, and the future of the industry.

Processes of Dairy Farming

Dairy farmers manage every aspect of a cow’s life—from what they eat and how much space they’re allotted to how much time cows spend with their offspring before they are separated. While approaches and restrictions vary from farm to farm, this imbalanced relationship between farmer and cow is criticized at length by animal rights activists, who believe animals have a right to life outside of human dominance.

Here are the main processes involved in dairy farming.

Breeding and Artificial Insemination

Reproductive management is essential to dairy farming because, like any mammal, cows must be pregnant in order to produce milk.

Dairy farmers often observe cattle for signs of estrus, or heat, which indicate the best time to be impregnated. From there, there are two standard ways in which farmers breed their cattle: natural service, also known as breeding with bulls, and artificial insemination (AI), the manual insertion of stored semen into the cow’s uterus.

Becoming widespread in the 1950s, AI has bred more than 66% of dairy cows in the United States, while natural service has sired about 25%. Reported benefits of AI include reducing the risk of disease and improving genetic predictability and success.

This approach requires multiple steps, including meticulous cleaning of the cow's vulva and insemination supplies, and a specific insertion technique to ensure a successful procedure. Proper insertion is challenging, as concluded by researchers at The Pennsylvania State University who found a varied success rate among professional technicians and owner-inseminators (between zero and 85%).

Cow-Calf Separation

Young calf in stable, Germany
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Cows have a gestation period of about nine months. How long newborn calves stay with and receive milk directly from their mothers depends on the individual farm.

On dairy farms, calves are taken from their mothers early on—sometimes even a few hours after birth—to maximize farmers' milk supply. When calves are separated, they are fed either milk or nutrient-dense milk replacer. Colostrum, the first essential milk produced by a mammal, is also critical to the newborn calf's development.

Female calves are often raised as dairy cows, while male calves are deemed useless to the dairy industry. There are typically three fates for males: Either they are raised and sold for beef production, killed early on to be sold as veal, or slaughtered at birth.


The vast majority of farms use automatic milking machines to milk cows. Before milking, most farmers carry out forestripping, where they remove a small amount of milk manually to stimulate the teats and identify any present infections, such as mastitis. Forestripping may go before or after cleaning and pre-dipping the teats. After these steps, farmers place the milking unit on the cow’s teats. 

The Food and Agriculture Organization recommends milking take place in the utmost hygienic conditions. Farmers must ensure the cows are properly and safely prepped for milking and that equipment is clean and well maintained.

Dairy Farms

Cows grazing in dairy farm
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Any industry contains competition between businesses, and generally, operations that are large, well-resourced, and financially stable have the most success. The same goes for the dairy industry. 

The industry is massive, with approximately 270 million dairy cows worldwide and 226 billion pounds of milk produced in 2021 in the United States alone. Large dairy operations with thousands of cows are more profitable and have lower production costs—and, thus, are more likely to remain in business—than small (under 50 cows) and midsized farms (about 300-400 cows). Smaller farms are also more likely to struggle with having a properly sized land base for their dairy herds.

Dairy cooperatives were formed to aid these struggles. In a cooperative, farmers receive support in the form of equipment, the bargaining of their milk prices, milk testing, and more. Still, cooperative membership may only help farmers so much as the number of farms across the United States continues to decline.

The U.S. lost more than half of its licensed dairy operations between 2003 and 2021—dropping from about 70,000 herds to below 30,000. Widespread drops in milk prices were primarily to blame, along with with a rise in feed prices. Although milk prices rose considerably to an all-time high in 2022, feed expenses and operating costs due to severe drought, increased labor costs, and other factors offset these gains.

Environmental Impacts

Despite a decline in the number of dairy operations, the industry maintains its substantial impact on the environment, contributing enormously to climate change and water pollution.


As ruminant animals, cows have unique digestive systems with a four-compartment stomach. The rumen is the largest compartment that stores and ferments feed that is consumed. Cows must release the gas they produce during digestion, also known as enteric fermentation, which amounts to 30-50 quarts of gas—predominantly carbon dioxide and methane—per hour. This is how their belches contribute to greenhouse gas emissions.

But cows' digestive processes are not solely responsible for the collective emissions. A frequently cited FAO report states that livestock accounts for 14.5% of human-caused greenhouse gas emissions. In addition to animal-produced methane and carbon dioxide, this statistic includes the footprint of feed for livestock as well as manure decomposition.

Methane contributes approximately half of the dairy industry's total emissions. Over 20 years, the global warming potential of methane is 84 to 86 times that of carbon dioxide. While dairy farms and companies have experimented with tweaking cows' diets in order to reduce their methane-filled belches, these projects are in their early stages.

Water and Land Usage

In addition to being a top emissions contributor, the dairy industry uses an enormous amount of resources. According to Bloomberg's reporting, 41% of U.S. land is designated for livestock. Nearly 160 million acres of that land is specifically for livestock grazing. The scale of animal agriculture has exacerbated the rate of deforestation and a decline in soil health, particularly when coupled with the mismanagement of manure and feed supply.

Water usage is another problem. According to the World Wildlife Fund, it takes about 144 gallons of water to produce just one gallon of milk. Of that water, about 93% goes to growing feed for dairy cows. The amount of water used for dairy milk is between two and 20 times the amount used for plant-based milk alternatives.

Cow Exploitation

Cows waiting
Overcrowded pens is one of the many issues activists have with dairy farming. Auldist / Getty Images

In addition to its environmental repercussions, dairy farming has long been called cruel by animal rights advocates. Along with the standard principle of animal rights—that animals do not exist exclusively to be used by humans—critics point to the many cited instances of cramped cattle quarters, poor nutrition, and disease spreading between cows on dairy farms.

The forced impregnation of cattle is another major issue. Not only are cows raised and bred solely to give birth and produce milk, but this process is also cyclic—cows with adequate fertility rates are repeatedly impregnated year after year, typically via artificial insemination. Once they are no longer fertile, they are either slaughtered or sold to beef farms.

The natural life expectancy of a cow is approximately 20 years. On dairy farms, however, that lifespan is cut to between four and a half to six years.

Early cow-calf separation is also considered cruel by opponents. Critics cite ethical concerns, emotional stress, and physical harm to both the calf and its mother when they are separated so early on in the calf's life. On the other hand, supporters claim it is best to separate the calf and cow as early as possible before they develop a bond—although this would not be a concern in the first place if there were no need to separate at all.

The Future of Dairy

Holstein dairy cows eating grass silage indoors
Automatic feed pushers can improve efficiency on dairy farms. Andrew Linscott / Getty Images

Many key players in the dairy industry seem aware of dairy's substantial environmental footprint and are taking measures to reduce emissions on farms. U.S. Dairy offers ambitious sustainability goals to reach GHG neutrality by 2050, and The Dairy Alliance references modern farming technologies and dairy cow's "upcycled" diets in vowing the industry's commitment to lowering emissions.

Even with eco-friendlier approaches, however, a report published in PLOS Climate argues that nothing would slash emissions and reduce the rate of climate change quite like the gradual phasing out of animal agriculture. The authors state that while strategies like reducing food waste and monitoring emissions can be efficient, a total shift from animal to plant agriculture would have a transformative effect—potentially offsetting 68% of carbon dioxide emissions.

"Phasing out" animal agriculture is not expected to take place on a global scale any time soon. It is also worth noting that this suggestion does not take into account that low-income countries depend on livestock for their income and nutrients, particularly in areas with limited resources.

That said, a gradual shift in milk consumption in the U.S. is already taking place. Americans have been drinking less cow’s milk since the 1940s, according to the USDA’s food availability data. Whereas 31.3 gallons of cow’s milk were consumed per capita in 1970, 17.3 gallons were consumed in 2017—declining almost 45% in those few decades. Competition from plant-based milk alternatives—almond, oat, soy, and other recently popular milks—is a significant cause of this decline.

Large-scale reductions in dairy farming and animal agriculture would accelerate this decline and lessen the impact of future climate catastrophes.

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