A farrowing crate is a metal enclosure used in pig farming that confines a sow (mother pig) in a fixed position during the birth of her piglets and through the nursing period. The crate is narrow enough to prevent the sow from turning around, with the primary goal of stopping her from accidentally crushing her newborn piglets when she lies down. It’s one of the most debated pieces of equipment in modern livestock farming, sitting at the intersection of piglet survival and animal welfare.
How a Farrowing Crate Is Built
A farrowing crate consists of metal bars arranged in a rectangular frame, placed inside a larger pen. The sow stands or lies within the barred frame, while piglets move freely in the surrounding pen area, called the creep area. The combined crate and creep space must be at least 3.2 square meters with a minimum length of 2 meters. Common pen dimensions are roughly 2.1 meters long by 1.65 to 1.8 meters wide.
The crate itself is sized so the sow can stand, stretch, and lie down, but not turn around. She should be able to stand without touching both sides of the crate simultaneously, and lie down without her snout and hindquarters touching the ends. Floors are typically made of high-tensile steel mesh or plastic tiles, designed to be cleanable and provide grip without being rough on the sow’s skin. Gaps in perforated flooring are kept to 10mm or less so piglet hooves don’t get caught. Between pens, removable dividers made from materials like plywood, fibre cement, or recycled plastic keep litters separated.
Many modern crates are adjustable, and some can swing open once piglets are older and more mobile, giving the sow more room during the later weeks of nursing.
Why Farmers Use Them
The core problem farrowing crates address is piglet crushing. A sow typically weighs 150 to 250 kg or more, and newborn piglets weigh around 1 to 1.5 kg. When a sow lies down in an open space, she can easily roll onto or step on piglets that don’t move out of the way fast enough, particularly in the first few days of life when piglets are weakest and least mobile.
Research comparing farrowing crates to open pens on commercial farms bears this out. A study across three herds found piglet mortality of 11.8% in crates compared to 13.7% in open pens. The gap persisted beyond the first week: in the second week of life, mortality in pens was 1.8% versus 1.0% in crates. In one herd, pen mortality was 8.5 percentage points higher than crate mortality, though the difference was smaller in other herds (4.4 and 1.9 percentage points, respectively). Indoor group housing systems, where multiple sows and litters share a large space, show even higher total piglet mortality at roughly 23.7%, compared to 18.3% in conventional crates.
How Long Sows Stay Confined
In conventional systems, a sow is moved into the farrowing crate about a week before her expected delivery date and remains confined through weaning, which typically happens at 3 to 5 weeks after birth. That means total confinement lasts roughly 4 to 6 weeks per litter. Some welfare codes cap this at 6 weeks maximum. A sow may go through this cycle multiple times per year.
Newer approaches use temporary crating, where the sow is confined only during the first few days after birth, when piglets are most vulnerable to crushing. In research trials, crates have been opened as early as day 2 and as late as day 14, with day 4 to day 7 being common. After the crate opens, the sow can move freely within her pen for the remainder of lactation. California’s Proposition 12 limits pre-farrowing confinement to 5 days and requires that breeding sows have at least 24 square feet of floor space with room to turn around, stand, lie down, and fully extend their limbs.
What the Crate Prevents Sows From Doing
The most significant behavioral restriction is nest-building. In natural or semi-natural settings, a pregnant sow spends the day before giving birth actively searching for a nest site, rooting, pawing at the ground, and gathering materials to build a nest. This behavior is deeply instinctive. Sows in open pens with access to straw or other materials perform significantly more rooting, pawing, and arranging than crated sows, who are physically unable to carry out these behaviors due to the lack of both space and materials.
Research suggests nest-building isn’t just a comfort behavior. It appears to play a role in preparing the sow physiologically for birth and lactation. Restricting it removes a behavioral need that sows are strongly motivated to perform, regardless of whether they’ve ever had access to nesting materials before.
Beyond nesting, crated sows cannot turn around, walk, or interact freely with their piglets. They can only stand, lie down, sit, and shift slightly forward or backward. This level of restriction for 4 to 6 weeks at a time is the central welfare concern.
Stress and Physical Health Effects
The physiological picture is more nuanced than you might expect. One study measuring cortisol (a stress hormone) in saliva found no significant difference between crated sows and sows in pens with temporary crating, either during confinement or 24 hours after crate opening. However, earlier research comparing crates to pens found higher cortisol levels in crated sows, but only at the end of lactation (around days 28 to 35), which may point to chronic stress that builds over time rather than an acute response.
Physical effects are more straightforward. Prolonged confinement on hard flooring contributes to shoulder sores, particularly in thinner sows who lose body condition during lactation. Lameness and teat lesions are also monitored as welfare indicators in crated sows. The limited movement means muscles weaken over the confinement period, though formal research isolating muscle atrophy specifically to farrowing crates is limited.
Alternatives to Conventional Crates
Several alternative systems exist, each balancing piglet safety against sow freedom differently.
- Temporary crating systems confine the sow for only the first week after birth, then swing open to give her free movement. These pens are slightly larger than conventional crates (4.3 to 6.0 square meters) and often include nesting materials. Products like the 360° Freedom Farrower use hinged elements that can be temporarily closed again when farm staff need to handle piglets safely.
- Zero-confinement systems never restrain the sow at all. Designs like PigSAFE use sloping walls, temperature differences between zones, and varied flooring to naturally guide the sow to lie down carefully and give piglets escape routes. These pens range from 4.8 to 7.2 square meters per sow and litter.
- Group systems provide individual open pens for farrowing, then allow sows and litters to mix freely in a shared enclosure. These require the most space, at 7.2 square meters or more per sow, and show the highest piglet mortality.
- Outdoor systems use individual huts or arcs placed in farrowing paddocks with straw bedding. Roughly 40% of British sows are kept outdoors. Total piglet mortality in outdoor systems (17.0%) is actually slightly lower than in conventional crates (18.3%), though conditions vary widely.
Cost Differences
Alternatives cost more, but how much more depends on the system. Purpose-designed pen systems, which offer a middle ground between full confinement and open housing, cost about 17.5% more than conventional crates in capital investment, with piglet mortality around 16.6%. That’s only marginally lower survival than crates, making these pens the most economically viable alternative. Indoor group systems, by contrast, cost 92% more than conventional crates and have substantially higher piglet losses, making them the hardest to justify financially.
Where Farrowing Crates Are Restricted
Legislation on farrowing crates specifically is still limited, though gestation crate bans (which restrict confinement during pregnancy, before the sow moves to a farrowing area) are more widespread. Ten U.S. states have passed laws restricting gestation crates: Arizona, California, Colorado, Florida, Maine, Massachusetts, Michigan, Ohio, Oregon, and Rhode Island. California and Massachusetts go further by banning the retail sale of pork from sows kept in gestation crates, even if the pigs were raised in other states. By 2026, these laws will cover less than 8% of the U.S. breeding hog inventory.
In the EU, conventional farrowing crates face increasing pressure. Several European countries are moving toward requiring temporary crating or free farrowing, though full bans with firm deadlines remain uncommon. Sweden and Switzerland have had restrictions on farrowing crates for years, while other countries are in various stages of transition.