Pork is one of the most widely consumed proteins in the United States, along with chicken and beef. And it’s big business in the United States, with U.S. pork exports through September 2022 totaling $5.6 billion. Production of this versatile, affordable protein has come under scrutiny in recent years and leaves people asking how pork is raised. Some states have taken steps to protect sows or gilts (female pigs that have not had litters) passing laws banning the use of gestation crates (or stalls). This brings the question, what are the housing alternatives for female pigs throughout their life cycle – specifically, when and why are crates/stalls used?

Types of Sow Housing

The National Pork Board explains that there are two main types of sow housing systems: Individual Housing Systems & Group Housing Systems.

Individual Housing Systems – also known as crates or stalls – allow sows to stand up and lie down. It minimizes sow aggression and injury, reduces competition for resources, provides for individual feeding and nutritional management, helps manage each sow’s body condition, and reduces worker injuries. However, individual housing systems also restrict movement and exercise, the ability to perform foraging behaviors and limit social interaction between sows.

Group Housing Systems can include various systems such as free access stalls, trickle feeding, and electronic sow feeding stations. Group sizes may range from five sows per pen to more than 100 sows per pen. In group sow housing, sows move about more freely and have social interactions with their pen mates. However, farmers may find it challenging to ensure each sow receives the proper individualized nutrition and minimize aggression and injury among sows. Foraging behavior may also be limited in group housing if no manipulable materials are present.

The Difference Between Farrowing and Gestation Systems

Farrowing stalls are specifically used shortly before a gilt or sow gives birth. When farrowing, sows need space to give birth. Farrowing systems are designed to provide sows the room they need to be comfortable during the birthing process while also providing room for their litter to move about freely and safely. A sow or gilt will have 12-13 pigs per litter. These piglets weigh 2-3 pounds at birth. Sows nurse piglets for about 21 days, at which time the piglets weigh 13-15 pounds and are weaned from their mother.

Sows are kept in farrowing stalls for a minimum of twenty-one days and sometimes for as long as thirty days to ensure the safety of her piglets. There is a 14 percent increase in mortality due to crushing and starvation when a sow is housed in a farrowing pen. In such a pen, the sow has more room to move around, but there is a higher risk of piglet mortality. According to the Pork Checkoff, “In general, individual farrowing stalls tend to improve piglet well-being through decreased mortality but limit the sow’s freedom. In loose-farrowing systems, freedom of movement and ability to express nesting behaviors are afforded to the sow, but piglet well-being may be compromised due to increased mortality.”

Farrowing systems should not be confused with gestation systems, as the former focuses on the health and well-being of the sow and her piglets after giving birth. Gestation stalls concentrate primarily on the health of the pregnant sow.

Pregnant sows or gilts may be kept in various gestational housing systems. Each system varies from farm to farm and may range from having all sows in gestation stalls that restrict their movement throughout their pregnancy to having animals in group housing the entire time until moving to a farrowing system to give birth. Of course, every sow-housing system has advantages and disadvantages, and producers consider the health and welfare of the animal very closely when determining the type of system for their farm.

In a hybrid system, sows are in gestation stalls for a short time before, during, and after insemination. Once pregnancy is confirmed, and injury to the fetuses is minimized, sows are put into group housing, ranging from a handful of pigs to 100, depending on the farm size.

Different Types of Farrowing Systems

When considering differences within farrowing systems, it largely comes down to size and how the area is configured. Systems can range from simple pens where there are few, if  any restrictions of movement on the sow and can progress to total confinement for a number of days in what is considered a traditional farrowing stall.

In a simple pen, sows are totally unconfined and do not have properly defined functional areas for defecation, resting, and feeding. While this pen provides shelter for the piglets, there is an increased risk in crushing piglets as the sow does not have a designated nesting area.

Another type of farrowing system is a modified pen. This system defines spaces within the area for resting, feeding, and defecation while also incorporating sloped walls, piglet protection systems, and nests. These systems vary in size depending on the manufacturer but are typically around 65 square feet.

Semi-confined farrowing systems or those with temporary constraints allow for greater sow movement by opening the farrowing crate during lactation. These systems typically use slat flooring and are about 46 square feet. In such a system, sows are confined for a minimum of two days immediately after giving birth to reduce piglet mortality due to crushing.

Finally, traditional farrowing stalls are farrowing stalls are typically 14 sq. feet per sow and may not allow the sow to turn around. These stalls open in the front and back, allowing easy entry and exit for sows. They come equipped with anti-crush bars to protect piglets and some are even adjustable to accommodate the size of the sow.

What Farrowing Systems Should Provide

Regardless of the system a farmer selects, the end goal is always to provide a safe, clean and comfortable environment for the sow and piglets. Unobstructed access to feed and water must be available to the sow and feeding and watering systems should be checked regularly to ensure proper operation.

Adequate space for the sow should be provided within the system. A sow should be able to lie down fully on her side easily. The sow should also be able to lie down entirely without having her head rest on a feeder bar and rear quarters touching the back of the stall simultaneously.

Adequate areas must be provided for the piglets and their unique needs. Each system should provide the following:

• A heat source to provide thermal comfort for the piglets in addition to that of their mother;
• Enough room for piglets to lie down without being on top of one another;
• Protection from the sow to avoid crushing; and
• Unrestricted access to the sow’s udder.

Also known as the creep area, the piglet space should provide supplemental feed for those piglets over 14  days of age and supplemental water as well.

Consumer Concerns About Sow Housing

In recent years, some states have taken steps to protect farm animals by passing laws that ban the use of battery cages for laying hens, gestation stalls for sows, and veal stalls for calves. These new laws threaten to cause shortages and upend the ag industry as producers work to comply with the new measures.

California’s Proposition 12 (Prop. 12), more formally known as the Prevention of Cruelty to Farm Animals Act, could have the most significant impact on the hog industry. Implementation has been delayed due to lawsuits by various groups opposing the law. Given the size of California’s economy, producer groups anticipate the law will be far-reaching as producers who want to market their protein in California need to comply with Prop. 12. This will create increased competition for pork produced compliant with Prop. 12, increasing prices to source products and ultimately increasing consumer prices.

California’s Prop. 12,  requires an allowance of 24 square feet per breeding animal and does not allow for temporary confinement of animals to exceed six hours in 24 hours and more than 24 hours total in any 30-day period. Note that this is a significant difference from the current pork industry housing standards of 16 square feet per pig. Additionally, it bans the sale of any uncooked pork product from a breeding animal that does not meet these specifications, no matter the state in which it originates.

The American Veterinary Medical Association and the American Association of Swine Veterinarians state that there is no one-size-fits-all approach. No animal housing option is perfect, and that’s why pig farmers rely on input from veterinarians and other animal health experts when determining which one will help maintain the highest levels of animal welfare.

Sow Housing Pros & Cons

When producers are selecting the type of housing that best suits their operation, they must take a number of things into consideration. While animal welfare is of utmost concern, the producer must also consider worker safety, ease of use, affordability of the system, space available for the number of sows farrowing, disease and many others.

It is suggested that producers work with their veterinarian to determine the best system for their operation when considering adding or converting systems. It is also suggested a producer discuss the project with their lender to do a cost/benefit allowance to determine the best course of action for all involved.

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The CLEAR Center receives support from the Pork Checkoff, through the National Pork Board.