Plant-Based Diet
Animal Facts

General:

Trillions of animals are killed every year for our pleasure. Whether you buy free-range, grass-fed or "certified humane", they are forcibly impregnated, their babies are stolen, their lives are cut extremely short and the slaughter process is horrific.
Millions of WILD animals are killed every year for being destructive to the agriculture industry. The US federal wildlife-killing program targets wolves, coyotes, cougars, birds and various other wildlife. They killed 2.3 million animals 2017.
Dehorning, debeaking, castration and tail docking are mutilations performed daily on factory farms without anesthesia and often resulting in infections.

Fish:

Fish FEEL PAIN. Anatomically, physiologically and biologically, the pain system in fish is the same as in birds and mammals.
Farmed fish suffer from severe depression and sometimes “drop out,” or float around lifelessly. They live in filthy, crowded water where infections and parasites spread, often eating their faces down to the bone. They're fed antibiotics and other drugs to keep them alive and growing faster than usual.
Fish suffer excruciatingly painful decompression when dragged from the ocean depths, often resulting in their swim bladders rupturing, their eyes popping out, and their stomachs being pushed up through their mouths. Then, when tossed onto the ship they slowly suffocate or are crushed to death. Others are still alive when they're slit open.
Fish are smart and sensitive. They have individual personalities, talk to one another, form bonds and grieve when their companions die. They are capable of remembering past social interactions they've had with other fish.
Fish use tools: some use leaves to to carry their eggs to safe places, others use a rock as an anvil to crack open clam shells.

A Manta Ray amidst the fish and bycatch caught by a trawler.
Photo Credit: Selene Magnolia / We Animals

Eggs & Chickens:

The egg industry IS the chicken slaughter industry, only worse. The hens are kept alive up to 18 months, rather than just six weeks for the broiler industry, to give humans eggs. Therefore, they suffer horribly for much longer, then are sent to slaughter in the very same manner as the broiler chickens.
Male chicks born in egg-hatching factories are useless to the egg industry, therefore killed immediately - shredded alive, gassed or suffocated.
Chickens raised for eggs naturally lay 12-18 eggs per year, but have been bred to lay them daily. They experience stress and anxiety when their eggs disappear, causing them to lay another. This strain greatly reduces their natural lifespan.
"Backyard chicken" eggs are not humane. The hens purchased from hatcheries still support the brutal killing of newborn male chicks. And hens suffer undue stress and shortened lifespans resulting from taking their eggs.
Certified Humane Cage-Free chickens are not raised humanely. They're raised in a large, dark building with thousands of others, with just over one square foot of space required per chicken. They can barely move and cannot get outside. Beaks are typically seared off with a hot blade. The beak is filled with nerves and debeaking causes serious and sometimes chronic pain. USDA Organic chickens have no space requirements, and treatment is even worse.
Chickens raised for meat are bred to grow so quickly they're often mobilized under their own weight.
Here's a great resource: 17 Chicken Facts The Industry Doesn't Want You To Know

Male chicks, useless to the egg industry, are dropped into a macerator and shredded alive after being hatched.

Dairy:

The dairy industry IS the meat industry, only worse. Dairy cows are slaughtered for meat at around 5 years of age (normal lifespan is 20 years). Male calves are either killed immediately or caged for a few months so they can't develop muscles, then killed for tender veal meat.
The dairy industry restrains and forcibly impregnates cows with sperm taken from males by anally electrocuting them to force ejaculation, or by restraining a female and getting the male to mount her and then manually redirecting the penis to an artificial vagina to collect the semen.
After birth, the babies are taken from their mothers amid cries from both (mothers will cry out for days). Mother and baby would normally share an unbreakable bond for life.
Male calves are killed immediately or sold for veal, females are fed grain or formula for a couple years until they begin the dairy cow cycle where they are milked daily and kept pregnant and nursing. This continues for a few years until they collapse from exhaustion and can no longer continue the cycle. They're then called "downers" and slaughtered for meat, usually around age 5 or 6, when their natural lifespan is 20 or 30 years.
Here are two great videos summarizing the dairy industry: Dairy Is Scary and Why Dairy is Never Humane.

A "downer" cow who can no longer stand from the exhaustive cycle of non-stop impregnation, baby-stealing and milking for years, will be literally dragged off to slaughter.

Wool:

The wool industry IS the meat industry, only worse. After years of bloody and brutal shearing they end up being slaughtered for meat.
In nature sheep grow just the right amount of wool and shed it when it gets warm. They don’t need to be sheared.
Sheep used for wool suffer profoundly. They’ve been bred to not shed and to have wrinkly skin so there’s more space for the wool to grow. This excess wool around their backsides means they remain dirty after defecating, which attracts flies who lay eggs in the dirty wool, resulting in painful maggot infections, called flystrike. To prevent these infections, farmers practice “mulesing” where they cut large areas of skin off around their backside WITHOUT painkillers. These mutilations often get infected and the sheep from this “preventative” measure.
Shearers are paid "by the sheep", not the hour, encouraging them to rush and throw the sheep around and brutalize them during shearing. Because of rushed shearing combined with the way we’ve bred sheep to have extremely wrinkly skin for more profit, sheep are often cut and then sewn up with no pain medicine.
After years of brutal and bloody shearing, when sheep fail to produce enough wool they’re sent to slaughter. Most sheep, from Australia, are packed by the thousands into crowded trucks and then ships for torturous journeys of up to three weeks, through hot and cold weather with no protection, before having their throats slit.
Sources: https://www.climatehealers.org/facts, PlantProof.com, WWF.org, FarmSanctuary.org/learn, CertifiedHumane.org

During brutal, rushed shearing, sheep are often cut and sewn up with no pain medication.

Human Rights:

It's not just an animal rights issue, it's also a human rights issue. Slaughterhouse workers are predominantly black and brown people living in low-income communities, and many are undocumented immigrants due to the extremely high turnover rates.
The psychological toll on slaughterhouse workers is increasingly being studied. Workers who are responsible for killing animals observe them being cut and dismembered will still conscious, as well as being skinned and boiled alive.
A former kill floor manager gave the following account: "The worst thing, worse than the physical danger, is the emotional toll ....Pigs down on the kill floor have come up and nuzzled me like a puppy. Two minutes later I had to kill them - beat them to death with a pipe. I can't care."

At the slaughterhouse, chickens are not stunned, but shackled and dragged upside down, fully conscious, through electrified water that paralyzes their muscles so that their feathers will come off more easily after they are dead.

Source: FreeFromHarm.org