Dairy cow standing in a crowded milking parlor, looking directly into the camera, representing the industrial conditions cows endure during milking.

“Cows love being milked”—a common claim that many have heard. But how true is it? Today's dairy cows produce nearly four times as much milk as they did fifty years ago¹, a result of intensive breeding and industrialized practices. But at what cost to their health and comfort?

This post explores whether milking truly hurts cows. By examining the biology of milk production, the realities of industrial dairy practices, and related health issues, we’ll uncover the truth behind the comforting myth of “happy cows.”

The Science of Milking: How It Works

Milk production in cows is a natural process that, like all mammals, begins after giving birth. When a calf gently suckles, it triggers nerves in the cow’s udder, prompting the release of the hormone oxytocin². Oxytocin then contracts the muscles around the milk-producing alveoli, gently squeezing milk down through the teats—a soothing process known as “milk let-down.”

In natural conditions, calves nurse frequently—up to eight or more times a day³. This ensures the mother cow’s udder is regularly emptied, maintaining optimal udder health and comfortable milk production levels.

Calf Suckling: The Natural Way

Calf suckling naturally evolved as a gentle, frequent, and responsive system. Calves instinctively nurse in a manner that supports excellent udder health. Studies consistently show that cows nursing their calves have lower rates of painful infections like mastitis, compared to cows milked exclusively by humans or machines⁴. Additionally, the natural process strengthens the emotional bond between mother and calf, providing both physical comfort and emotional well-being⁵.

From Natural Process to Industrial Practice: How Dairy Farming Changed Everything

To truly understand if milking hurts cows, we need to consider the entire context of dairy farming, not just the few minutes it takes to extract milk. Dairy farming isn't a rescue operation providing cows with comfort or a spa treatment; it's a carefully managed industry designed solely around maximum milk production. Cows aren’t brought into existence out of compassion but are intentionally bred, housed, and managed to ensure the greatest possible milk yield, often at a significant cost to their health and well-being.

The Impacts of Selective Breeding for High Milk Production

Modern cows kept for dairy, especially breeds like Holstein-Friesians, have been selectively bred to maximize milk output. These breeding practices have dramatically altered cow physiology, creating oversized udders that carry heavy, unnatural burdens⁶.

Oversized Udders: Heavy, pendulous udders cause physical strain, difficulty moving, and increased risk of injury.
Increased Mastitis Risk: Larger udders and higher milk production significantly heighten the risk of mastitis, a painful bacterial infection of the udder⁷.
Shortened Lifespan: High-producing cows typically live shorter lives, frequently culled after only three to four lactations due to health problems or declining milk output⁸.

Industrial Milking Methods: From Hand Milking to Robots

Historically, cows were milked by hand. Hand milking could be gentle, but inconsistency and human error frequently caused teat injuries⁹. As dairy farming industrialized, machines took over, applying vacuum suction to mimic natural calf suckling. While efficient, improper use or equipment malfunction can cause significant teat damage and increase infection risks¹⁰.

More recently, robotic or Automated Milking Systems (AMS) allow cows to be milked without direct human involvement. Despite initial stress during adaptation, cows generally adjust—but research indicates their visits to robotic milkers are driven primarily by feed rewards and relief from udder discomfort, rather than intrinsic enjoyment¹¹.

Regardless of the milking method, cows endure significant physical and emotional burdens as a result of being treated primarily as milk-producing machines rather than sentient animals.

Cow in milking parlor

Cow udder being milked

Milking Parlor

Common Udder and Teat Health Issues in Cows on Dairy Farms

A cow’s teats and udders are extremely delicate, sensitive organs that are prone to suffer in industrial dairy settings. The continuous strain and unnatural size of modern udders frequently lead to chronic, painful conditions:

Teat Injuries and Lesions: Frequent machine milking and high vacuum pressure can cause teat-end hyperkeratosis (callusing and cracking), broken blood vessels, and even open sores¹². These injuries are painful and significantly increase infection risks.
Mastitis: Extremely common in cows used for dairy, mastitis causes swelling, severe pain, and significantly reduced milk production. It is a direct consequence of intensive milking practices and genetic selection for high yield¹³.
Udder Edema and Strain: Oversized udders commonly cause painful swelling, skin abrasions, and impaired mobility¹⁴.

These health issues are not isolated incidents, but inherent to the intensive production methods used in dairy farming today.

Are Cows Really “Happy” to Be Milked?

The industry often portrays cows as contented and eager to be milked—but the reality is more complex. While cows do experience relief when overly full udders are emptied, this relief should not be confused with enjoyment. Behavioral studies and physiological measurements (such as stress hormones like cortisol) consistently show cows experience stress during milking, particularly if conditions are unfamiliar, painful, or stressful¹⁵.

Cows primarily enter milking parlors because of routine, the discomfort of full udders, or the reward of feed—not because they enjoy the process itself¹⁶. Thus, claims that cows are “happy” to be milked greatly oversimplify the realities of their daily experiences.

Rethinking Our Relationship with Dairy

So, does milking cows hurt? Under natural, low-yield conditions with calves nursing regularly, milking does not cause harm. However, industrial dairy farming is anything but natural. Selective breeding, intensive milking practices, and systemic separation of calves transform this natural process into one often followed by chronic pain, physical suffering, and emotional distress for cows.

Increasing awareness about the harsh realities of modern dairy farming has led many to explore plant-based alternatives—choices that not only reduce animal suffering but also provide environmental and health benefits. Each time we reconsider our reliance on dairy products, we take a compassionate step toward reducing the demand that drives these practices.

Sources & Further Reading

¹ U.S. Council on Dairy Cattle Breeding, 2023.
² DairyNZ, "Milk Let-Down Physiology," 2021.
³ Von Keyserlingk & Weary, "Maternal Behavior in Cattle," J. Dairy Sci., 2019.
⁴ González-Sedano et al., "Residual Calf Suckling and Mastitis," 2010.
⁵ Flower & Weary, "Effects of Early Separation on Cow and Calf Behavior," 2001.
⁶ Compassion in World Farming, "Impact of Selective Breeding on Dairy Cow Welfare," 2020.
⁷ Xia et al., "Udder Health in High-Producing Cows," 2022.
⁸ USDA Dairy Report, "Cow Longevity Trends," 2022.
⁹ Gorewit et al., "Endocrine Responses: Hand vs. Machine Milking," J. Dairy Sci., 1992.
¹⁰ Natzke et al., "Effects of Overmilking on Teat Tissue," J. Dairy Sci., 1982.
¹¹ Hopster et al., "Adaptation of Cows to AMS," Applied Animal Behaviour Science, 2002.
¹² National Animal Disease Information Service (NADIS), UK, "Teat-End Hyperkeratosis and Health," 2021.
¹³ Medrano-Galarza et al., "Mastitis in Dairy Herds," Frontiers Vet Sci., 2017.
¹⁴ Green et al., "Lameness and Mobility Issues," Journal of Dairy Sci., 2014.
¹⁵ Wagner et al., "Stress Responses to Milking," Applied Animal Behaviour Sci., 2015.
¹⁶ Prescott et al., "Motivation of Dairy Cows to Be Milked," Animal Welfare, 1998.

Does Milking Hurt Cows?