A year in the making, a national veterinary group releases its official policy statement on sows confined in gestation stalls.

The debate over sow stalls vs. group sow housing may never be over, but at least the two camps have developed an official policy that says neither option has an advantage over the other.

The American Veterinary Medical Association (AVMA) recently revised its official policy for pregnant sow housing, which says both systems offer advantages that should be retained, while improvements are made to overcome problems (see sidebar on p. 11).

Managing Sow Comfort

Some pen advocates, such as animal handling and livestock behavior expert Temple Grandin of Colorado State University, have argued that stalls represent very poor housing systems because sows are becoming bigger and crates are becoming narrower, commonly 20 to 24 in. wide.

That situation may exist, says Kansas swine veterinarian Lisa Tokach, but the problem usually is not with the stalls. The problem lies with the management (or lack thereof) of the system.

“The issue is really not about the housing. It's about the people and their level of animal husbandry,” she says. “I have clients who use stalls, and when they use them in the correct manner, they are better able to control the sow's individual environment and their body condition and give them more individual attention.

“But, admittedly, I have had people who have abused the stall. They have used it without applying good animal husbandry and it can be a bad thing, such as letting sows get too big for the crates,” she says.

Tokach says proper sow management starts with doing a good job of body conditioning, “so you don't get this sixth-parity sow that's huge and overconditioned.”

On many of the Kansas farms for which Tokach consults, clients are measuring backfat at each parity, trying to keep within the stated guidelines.

Most of her clients also use a combination of stalls and some pens to accommodate larger sows.

She also points out research showing injury rates for stalls as actually lower than for group sow housing systems.

As with stall housing, Tokach counts a number of producer clients who do a “fabulous job” of running group sow housing systems.

There are good sow stall systems and good sow pen gestation systems — how well they work depends almost entirely on the management expertise, she adds.

Defending Sow Stalls

“Our main argument was that the literature review we conducted for the AVMA supports that there is no data showing putting sows in stalls is detrimental in terms of health, injuries or lameness,” says the Kansas veterinarian.

The animal behavior researchers also argue that stalls produce sow boredom and stereotypical behavior such as bar biting, which indicates that sows in stalls are unhappy. But there is no factual evidence to support either of those contentions, she stresses.

CSU's Grandin also argues that a major issue not being addressed by the pork industry is bossy and aggressive sows.

But Tokach counters that aggression is just a fact of life, whether it be sows, cows or people.

Good management can deal with aggression; for example, grouping females uniformly to reduce size disparity within the group and considering different feeding regimens.

“We are doing some experiments with dropping smaller amounts of feed 10 times a day to reduce the stress of feeding,” explains Tokach. Even if the boss sow “hogs” all of the feed during the first three drops, she likely will eat her fill and provide plenty of opportunity for timid sows to eat during the remaining seven feed drops.

Tokach was one of five members of the American Association of Swine Veterinarians (AASV) serving on the 13-member task force this summer that hammered out the revised AVMA policy on gestation sow housing.

Tokach, who works at the Abilene (KS) Animal Hospital, also sits on the AASV animal welfare committee.

AVMA Revises Sow Housing Policy

The American Veterinary Medical Association (AVMA) has revised its policy on pregnant sow housing. The policy states there is no preferred type of housing and that current advantages should be retained while improvements are developed.

The 13-member, multidiscipline task force conducted an extensive, one-year review of more than 200, peer-reviewed, scientific studies that dealt with the health and welfare of housing breeding sows in gestation stalls. The position statement can be reviewed on the AVMA Web site at www.avma.org/policies/animalwelfare.asp#sowhousing.

A review of the science of animal welfare turned up these key findings:

  • Physiology: Gestation stalls do not induce a physiologic stress response compared to group housing for pregnant sows.

  • Behavior: Sows show different behavior housed in stalls than pens due to restricted movement, reduced caloric intake, reduced opportunities to forage, absence of bedding and restricted social interaction.

  • Production: Sow performance in gestation stalls is no different than sows kept in groups.

  • Health: The rate of sow injury is reduced in gestation stalls vs. group housing.

In addition, the task force offered these considerations for sow housing:

  • Management: This in itself is a major determinant of animal welfare. Some housing systems can be expected to work well at one level of management, but not at another.

  • Feeding system: Limit feeding helps avoid health problems, but it can produce chronic hunger, restlessness, motivation to forage and competition for food. Systems may work well with one feeding system but not another.

  • Environmental features: Certain environmental features allow sows to occupy their time and escape from aggressive group mates. How well a housing system works may depend on the existence of these features.

  • Sow type: Important genetic differences influence how sows function in different housing systems. There are also individual differences; a housing system that is good for more dominant animals may not work with more passive sows.

Clearly, no single sow system fits all situations or animal welfare criteria.

The task force concluded that sow housing systems should:

  • Minimize aggression and competition among sows;

  • Protect sows from detrimental effects associated with environmental extremes, particularly temperature extremes;

  • Reduce exposure to hazards that result in injuries, pain or disease;

  • Provide every animal with daily access to appropriate food and water;

  • Allow observation of individual sow appetite, respiratory rate, urination and defecation, and reproductive status by staff; and

  • Permit sows to express most normal patterns of behavior.

Finally, refinements should be made in current sow housing systems provided technology is sound, the skills needed to operate such systems can be adopted with confidence, and systems are economically viable.