Pigs for Meat Breeding Sows On the Farm In the Slaughterhouse Did you Know?

Life of a Pig on a Factory Farm

Pigs for Meat

In 2022, approximately 27 billion pounds of pork was produced in the U.S. across more than 67,000 pig farms. Annually, around 74 million pigs are raised on farms, at least 93% of them on factory farms.

In pigs, the natural weaning process takes two to three months, but on factory farms, piglets are taken away from their mothers after just three to four weeks. They are then crowded into metal-barred and concrete-floored pens in giant warehouses where they will live until they are separated to be raised for breeding or meat. More than one million pigs die annually just during transport to slaughter, and as many as 10 percent of pigs are “downers,” animals who are so ill or injured that they are unable to stand and walk on their own.

Factory farmed male piglets are frequently castrated without anesthesia or pain relief. Also without anesthesia, notches are also taken out of piglets’ ears for identification and their tails are severed to minimize tail biting, a behavior that occurs when pigs are kept in deprived factory farm environments.

Meat pigs are kept in extreme confinement until they reach a slaughter weight of 250 pounds, usually at 6 to 7 months of age. 

Pigs for Breeding

Of the roughly 74 million hogs and pigs living on farms, roughly 70 million are market hogs, while around 6 million are kept for breeding. Breeding sows are treated like machines, living a continual cycle of impregnation and birth. Each sow is forced to produce more than 20 piglets a year with little time to recover between pregnancies. Many factory farms are now striving for litters of upwards of 40 piglets per sow. During their pregnancies, sows are kept in two-foot wide gestation crates, intended to allow pigs only enough movement necessary to stand up and lie down in place. There are typically 100 or more sows kept in a single warehouse, in gestation crates placed side by side in rows of 20 sows each. These pigs frequently chew on the bars of their crate out of stress and boredom.

At the end of their four-month pregnancies, the sows are moved into farrowing crates, where they spend about a month until their piglets are weaned. Farrowing crates are slightly larger than gestation crates to allow the sows to lie on their side to nurse. The natural weaning process lasts about two to three months, but factory farmed piglets are removed from their mothers to be fattened after just three to four weeks. Sows are re-impregnated and returned to the gestation crates. This cycle continues for a sow’s entire life, about three to five years.

On the Farm

This continuous grueling cycle of moving breeding sows from gestation crate to farrowing crate to gestation crate was developed as an economically efficient method of pork production, requiring less labor and feed than other housing arrangements. Yet researchers have found that outdoor, crate-free systems, and group housing systems are better for sow health and longevity.

Alternative housing exists. An Iowa State University study found that sows housed in group pens produced healthier, larger litters, and were breeding faster after weaning compared to sows in confined housing (link to the study below). Research also supports that group housing allows for better welfare, as sows are more able to express natural behaviors. More technologically advanced forms of group housing, those which allow you to track individual sow food intake, can also help farmers better track the health of their sows and save money. Some studies have stated that group housing can increase lameness and aggression in herds, but this is easily avoidable within farms. Proper flooring (not slatted concrete), with bedding will keep sows from developing lameness. Introducing sows slowly and understanding social dynamics, along with proper feeding methods will keep herd aggression low. Other alternatives to gestation-crate housing systems include “turn-around” stalls, free-range systems, and indoor group housing.

• Turn-around stalls can be slightly larger than customary gestation crates or have a moving wall that allows the sow to turn around inside the crate.
• Free-range systems afford sows access to the outdoors and, optimally, give pigs the freedom and materials to express natural behaviors like nest-building and rooting.
• Indoor group housing systems house pigs in groups of up to several dozen in communal indoor pens, giving them freedom to move and the opportunity to socialize. Group-housed sows can be fed through automated or manual distribution of food. Some stalls are fitted with a back gate or an automated, controlled rate feeder to eliminate competition for food. The electronic sow feeder system allows entry of one sow at a time, identifies her through an electronic tag or collar, and distributes the appropriate ration. When the sow finishes eating, she leaves through a separate exit and the next sow may enter.

The overcrowding and confinement that is typical of pigs in factory farms is unnatural. Pigs are actually very clean animals; if they are given sufficient space, pigs are careful not to soil the areas where they sleep or eat. But in factory farms, they are forced to live in unsanitary conditions—in their own feces, urine, vomit and the corpses of other pigs.

Physical/Behavioral Effects

Scientific evidence suggests that intensive confinement causes physical disorders in sows. Unnatural flooring and lack of exercise leads to obesity and crippling leg disorders. Further, the air in pig factory farms is laden with dust, dander, and noxious gasses, which are produced as the pigs urine and feces builds up inside the warehouses. These problems cause respiratory difficulties and spread infectious diseases amongst the pigs.

Psychological Effects

Scientific evidence also indicates that intensive confinement causes psychological disorders in sows. The lack of environmental stimulation in the stall environment and the sows’ inability to perform normal behaviors (rooting, foraging, nest-building, grazing, wallowing, social behaviors) leads to psychological disorders including chronic stress, depression, and aggression. Sows can also develop abnormal and neurotic coping behaviors, such as bar biting and sham chewing (chewing nothing).

In the Slaughterhouse

In addition to overcrowded housing, pigs also endure extreme crowding during transportation. This crowding often results in rampant suffering and death, even before they arrive at the slaughterhouse. At the slaughterhouse, pigs are first supposed to be “stunned” and rendered unconscious, in accordance with the federal Humane Slaughter Act. The stunning is done prior to being hung upside down by their back legs and having their throats sliced open with a knife so that they may bleed out. However, stunning at slaughterhouses is terribly imprecise. Conscious pigs are often left to hang upside down, kicking and struggling, while a slaughterhouse worker attempts to slice their throats. If the worker is unsuccessful at this first station, the pigs will be carried to the next station on the slaughterhouse assembly line, the scalding tank, and boiled alive fully conscious.

Fortunately, Massachusetts has taken a step in the right direction for animal welfare. In 2016, voters passed a ballot measure that prohibits the inhumane confinement of egg-laying hens, breeding pigs, and veal calves, as well as the sale of products made from animals raised using the production methods.

Learn more:

• Livestock Slaughter, USDA, 2024
• Humane Methods of Slaughter Act, USDA website
• Massachusetts’ 2016 Ballot Question

Did you know?

• In natural settings, pigs live in social groups, often sleeping huddled together.
• Pigs can recognize and remember up to 30 other individuals, and greet each other by making nose-to-nose contact or by grooming.
• Pigs are capable of learning complex tasks, perceiving time, and anticipating future events.
• Mother pigs use a special grunt to tell their piglets it is time to suckle.
• When released from confinement to semi-natural enclosures, sows quickly revert to natural behaviors like rooting, nest-building, and traveling long distances.
• A pregnant sow may walk up to six miles before finding a sufficiently protected area to build her nest, and can take up to ten hours to complete her nest.
• Pig snouts are highly sensitive and help them find a wide variety of foods such as fruits, roots, mushrooms, grasses, earthworms, snakes, and rodents.