× Expand AP Images Farm Scene Pitiful Poultry A typical battery cage holding egg-laying chickens.

U.S. factory farms, where an estimated 99 percent of farmed animals are kept, are almost as inaccessible to the public as they are inescapable for the animals locked inside. When I started getting more involved in discussions about animal farming, I knew I had to see the inside of one of these facilities for myself. I finally got my opportunity with a rescue team from a California farmed animal sanctuary.

The sanctuary was able to convince a handful of farmers to allow them to rescue some of the chickens in their spent flocks. The industry term “spent” is used to describe hens whose reproductive systems are too worn out to be profitable, at which time the animals are killed. These hens were bred to lay eggs, not produce meat, so they can’t be sent to the slaughterhouse. Farmers would have to spend money killing the hens and disposing of their bodies; relinquishing them to the rescuers spares the farmers that cost.

The rescue took place at a battery-cage farm in the Central Valley of California in early 2016. Battery cages are thin wire enclosures that are typically so small the hens can’t even spread their wings. They’re named for the way identical units are stacked end to end, like electrical batteries.

In 2008, California residents passed Proposition 2, a ballot measure in California that added this section to the California Health and Safety Code: “In addition to other applicable provisions of law, a person shall not tether or confine any covered animal, on a farm, for all or the majority of any day, in a manner that prevents such animal from: (a) lying down, standing up, and fully extending his or her limbs; and (b) turning around freely.”

More than eight million California residents turned out in favor of Proposition 2, the highest positive turnout for a citizen initiative in the state’s history. Many thought this would end the cruel confinement of egg-laying hens in the state. But despite the overwhelming public support for the bill, reform can be slow, and these dreadful cages are still common.

In order to comply with the new law, the farm I visited had simply taken out the walls separating the batteries. This means that each hen has more total space in her “cell,” but she has more cellmates. Recent investigations have shown that some California farms haven’t even made these changes, and there has been only one recorded enforcement of the law in the entire state, which was home to an estimated twelve million egg-laying hens in 2017.

We entered the farm before sunrise so the sleepy birds would be less anxious and easier to handle. We drove through a large metal gate with signs warning keep out and biohazard, and passed a dozen sheds with metal roofs and walls of plastic netting. The stench of ammonia was burning our mouths and throats, even outside the barns. We unloaded our transport crates, donned our disposable coveralls, sanitized our boots, and entered the designated shed.

From the entrance, we looked down a dozen rows of cages, each approximately 150 feet long. Cages were stacked on each other in two levels, one just above and one just below eye level. On the floor below them was a six-inch-tall, foot-wide mound of feces, which at first looked hard enough to stand on, but the new volunteers got ample warning from veterans that the dry exterior hid a moist, rotting interior. The birds were already agitated from hunger when we came in—the farm didn’t waste any money on feeding them before we arrived—but the lights and our presence stressed them out further.

In the absence of rescue, the spent hens face a cruel fate. In normal circumstances, a farmhand pulls a large wheeled box down each row, grabbing the chickens by whatever body part is accessible and ripping them out through the tiny doors of their cages, breaking limbs and tearing skin in the process. The hens are then thrown into the dark, cramped chamber until it’s full, and the little air that is left in the box is replaced with carbon dioxide.

Injured, confused, and terrified, the chickens die slowly from asphyxiation in a cage of flesh. Hens used for eggs are typically killed at between a year and a half and two years old, a small fraction of their potential lifespan. Of the thousands of birds slated to be killed and discarded on this one farm that day, we could save only a few.

We worked in teams to transfer the hens from the cages to our transport crates. Some of us reached into the cages to pull out the birds—bruising our arms on the edges of the narrow doors as we carefully pulled out one bird at a time, holding her wings against her body so she didn’t flap them and break one on the way out—while other rescuers opened and closed the transport crates.

The hens tried desperately to escape our reach, crowding into the corners of the cages and dodging our hands. Some bit us, others cried out in fear when rescuers picked them up, and many were breathing heavily and with open mouths, an indicator of stress. Many birds had wounds from fighting and climbing over each other in the cramped cages, and injuries from incessant contact with the metal cage. Some were missing eyes and had infected cuts from broken wire.

In each cage, you could tell who the dominant birds were and who had been picked on. All the birds were thin, but those who had been bullied were severely emaciated. They were missing many feathers, which other birds had pecked off in agitation. Anxiety had driven some birds to peck off their own feathers. There were many dead birds, some whose legs and heads hung limp and were beginning to decompose after they had become hopelessly trapped between the wires of their cage walls.

Each rescuer managed the experience differently. Some people’s hands shook while they consoled the hens, promising them that they would soon be free of this hellhole. Some quietly let tears roll down their faces while they worked on the task at hand with solemn tenderness. Others were angry and snapped at fellow rescuers for any misstep.

My focus was on diligence and observation. I hoped to absorb as much as I could from the experience, in particular the perspectives of the hens themselves. I needed to remember these stories, not just of the hens who made it out alive to live happily at the sanctuary, but also those who remained on that farm—dead or alive. This harrowing experience helped me put a face—actually more than seven thousand faces in the shed we visited—on the horrors of animal farming.

In the fall of 2016, dozens of animal advocates descended on Massachusetts from across the country, joining hundreds of in-state activists, to participate in the “Yes on 3” campaign for the November ballot. I was able to join for the last few days leading up to the vote on the referendum. We went door-to-door discussing the measure, which sought to prohibit the most extreme farmed animal confinement, similar to Prop 2 in California.

Most of the conversations were short; the residents just told us they had already voted or were definitely going to vote in favor. In fact, the measure ultimately received an overwhelming 77.7 percent of the vote. Interestingly, almost everyone I spoke to about the initiative brought up how upset and concerned they were by footage they had seen from undercover investigations of animal farms.

This is a common experience for advocates of both plant-based eating and farmed animal welfare. Almost everyone who cares about the issue does so because of videotaped investigations of animal farms, and the most dedicated, passionate people in the movement are even more likely to be driven by their knowledge of the suffering farmed animals endure—which they learned about through investigations—than other information such as environmental and health concerns. If I had to choose one strategy that has built the most momentum for the movement, it would be the undercover investigations that have exposed and publicized the implications of the modern “machine in a factory” approach to farming animals.

In the fall of 2016, dozens of animal advocates descended on Massachusetts from across the country, joining hundreds of in-state activists, to participate in the “Yes on 3” campaign for the November ballot.

Undercover investigations of animal farms essentially began in the early 1990s, following investigations of animal testing laboratories in the 1980s. Of course, there were earlier exposés, such as Upton Sinclair’s work leading to the publication of his novel The Jungle in the early 1900s. It seems the first investigation of the modern era was conducted by the pioneering animal rights organization People for the Ethical Treatment of Animals (PETA) in 1983 at a Texas horse exporter, shortly after PETA’s famous lab animal investigation in Silver Spring, Maryland, in 1981. More food-industry investigations followed in 1991, when PETA investigated a cow slaughterhouse, a pig slaughterhouse, and a chicken hatchery.

The first modern animal farm investigation, in 1992, exposed the cruelty at Commonwealth Enterprises, a New York farm producing foie gras, the fattened liver of a duck or goose. The major finding was that, contrary to prior claims by the company, the ducks were force-fed. Three times a day, each worker would shove a long, metal pipe down the throats of around five hundred birds. The pipes caused the birds serious pain and resulted in subsequent health issues such as damaged esophagi and pneumonia.

This research led to the first U.S. police raid of an animal farm, though reports by activists suggest the foie gras industry successfully pressured the district attorney into dropping the charges. Federal law at that time, and today, excludes farmed animals from standard animal-cruelty protections.

These investigations started receiving major media attention in the late 1990s. A 1998 PETA investigation of a pig-breeding farm led to the first felony indictments ever for cruelty to farmed animals. It “revealed shocking, systematic cruelty, from daily beatings of pregnant sows with a wrench and an iron pole to skinning pigs alive and sawing off a conscious animal’s legs.”

PETA’s McCruelty campaign against McDonald’s in 1999 and 2000 led to one of the first major corporate commitments to reducing farmed animal suffering, though PETA has since restarted its campaign after McDonald’s failed to take continued steps to increase welfare.

Since undercover investigations began, one of the biggest contributors to their success came, inadvertently, from animal agriculture lobbyists. The meat, dairy, and egg industries tried to stop investigations by passing laws in state legislatures to limit the ability to document animal farm operations. The first such law, passed in Iowa in 2011, prohibits undercover audio or visual recording of an animal facility, and possessing or distributing any such record.

In essence, animal ag has sought to punish those who expose abuse, rather than those who commit it. The public backlash to these “ag-gag” laws, as they are now widely known, began as soon as they were discussed in the mainstream media. Food columnist Mark Bittman popularized the term in a New York Times article shortly after the Iowa law was passed. He referenced a Texas investigation from earlier that year that showed calves being hammered to death by workers, animals confined in tiny crates with barely enough room to turn around, pervasive health issues, and the standard industry practice of dehorning calves by burning the budding horns out of their skulls with hot metal cutters.

These laws have been passed in numerous U.S. states, though many have failed, and the Idaho and Utah ag-gag laws were struck down in the courts as unconstitutional. Numerous journalists and public figures have denounced the laws, and that coverage has led many to speak out against eating meat and against the animal agriculture industry as a whole. A psychological experiment even corroborated this effect, suggesting that simply learning about the laws led to decreased trust in farmers and increased support for animal welfare regulation.

Since 2013, the industry has quietly continued to push ag-gag laws through state legislatures, despite public opinion. In August 2013, a policy representative from the National Pork Producers Council said, “We did a study of coverage of ‘ag-gag’ laws that found that 99 percent of the stories about it were negative.”

When investigators and other advocates share videos and otherwise engage with the public, they need to include an “ask,” or request—some action an inspired viewer can take if they want to help end the animal cruelty, environmental damage, or other harm they’ve seen. This activism can be very compelling.

A recent advance has been the use of virtual reality headsets to immerse the audience in the life of a farmed animal. This tactic has been pioneered by Animal Equality; one video takes the audience through a chicken slaughterhouse via a camera hanging between two chickens, as a worker sharpens his knives in front of them, ready to slice the throat of each passerby. For the past three decades, the movement’s ask for viewers eager to take action has almost exclusively been for individual diet change, either for the viewer to reduce their meat consumption or leave animals off their plate entirely.

How successful has this been? The data here is limited. The numbers of self-identified vegetarians is growing but still under 10 percent. Survey results indicate around 54 percent of Americans are “currently trying to consume fewer animal-based foods (meat, dairy, and/or eggs) and more plant-based foods (fruits, grains, beans, and/or vegetables).”

Yet a 2014 U.S. survey found that 93 percent of respondents felt it was “very important” to buy their food from humane sources. Eighty-seven percent believe “farmed animals have roughly the same ability to feel pain and discomfort as humans.” And an astounding 47 percent of U.S. adults say in a survey that they support the seemingly radical policy change of “a ban on slaughterhouses.”

Excerpted with permission from The End of Animal Farming: How Scientists, Entrepreneurs, and Activists Are Building an Animal-Free Food System, by Jacy Reese, Beacon Press, 2018.