A University of Illinois animal scientist offers support for individual stalls, while a Canadian scientist provides an overview of group sow housing research.

Can the sow gestation stall be saved?

University of Illinois animal scientist Janeen Salak-Johnson thinks so, although she believes a modified version may end up being best suited to meet the needs of today's larger and leaner pregnant female.

Sows in Transition

Back in 1989, Stan Curtis of the University of Illinois documented that the standard, 2×7-ft. sow stall was actually larger than the average gestation sow, but still did not allow for normal postural adjustments that animal activists claim are necessary for animal well-being, she explains.

A “turn-around” stall was developed at the time, but Curtis says the industry chose not to adopt it, perhaps because it was “ahead of its time,” Salak-Johnson relates at the Sow Housing Forum in early June at Des Moines, IA.

Now sows are much larger, which has further fueled the sow welfare debate.

A 2004 paper from John McGlone and colleagues from Texas Tech University indicated that less than 40% of sows studied across several large U.S. farms could fit into a standard gestation stall without touching the sides of the crate, says Salak-Johnson.

“Today, most sows housed in the standard gestation stall cannot turn around or lie down in full recumbence without either touching the feeding trough or stall walls, and social interactions among sows are limited,” she points out.

There are new options available, including the “free access” stall from Germany (Chore-Time acquired U.S. rights), which Salak-Johnson previewed during an industry trip to Europe last November. The system allows the sow to choose whether to stay in an individual stall or move to an adjacent pen area with other sows.

“After watching this system, it is clear that sows choose to lock themselves in the stalls,” she stresses. The use of individual stalls permits individual feed management, reduces aggression and improves animal observation.

Since sows in the free-access stalls seem to habitually return to the same stall, individual feeding management can still be applied. And concerns about sows being too large or stalls being too small are also addressed. The width of the stalls can be adjusted, which would require that all stalls be adjusted, although some sows may not need the additional space, Salak-Johnson says.

But the system works. Sows in groups of 40 with the “free access” stalls she surveyed did not have lesion problems. German producers report most of the time these sows prefer to stay locked in their stalls.

Science-Based Decisions

The challenge for the U.S. pork industry is developing science-based evidence that shows what sows really require for animal well-being, in order to make informed decisions on sow gestation housing, Salak-Johnson observes. “Right now, we don't have guidelines for producers that truly enhance the welfare of that sow. A lot of the decisions made up to this point have been based on economics and not on whether housing improves the well-being of the sow.”

Salak-Johnson clarifies that gestation stalls have not actually been banned in the European Union, despite the ruling they are being phased out by 2013. The fact is, producers will still be permitted to keep bred sows in individual stalls for at least five weeks after breeding.

Moreover, veteran European producers have stressed they plan to stay with individual sow stalls as long as possible, whereas young producers profess to have no problems managing group-housed sow systems.

For the United States, Salak-Johnson sees no reason to move away from individual stalls until the science says otherwise.

Virtually all studies to date indicate stalls vs. pens constitute a tradeoff when performance parameters are compared. She cites recent reports that indicate welfare challenges change over time. During early gestation, group-housed sows showed an increased number of scratches, higher estrus return and higher cortisol concentration vs. sows in individual stalls that showed increased lameness during late gestation.

Those results correspond to findings from Salak-Johnson's research. She found lesion scores for group-housed sows increased at mixing, plateaued during mid-gestation and increased once again during late gestation. She suggests this may mean sows need to be managed differently during different stages of reproduction.

Three Reasons for Stalls

Contrary to the claims of animal rights activists, Salak-Johnson says there are three reasons why individual stalls shouldn't be discarded and can still provide a viable environment for the sow:

  • It is possible to improve and modify the gestation stall and implement management strategies utilizing modified, individual housing equipment that will ensure the well-being of the sow;

  • Today's producers who follow current animal care guidelines are already providing environments that are better for the sow than in the past; and

  • Producers and scientists do have sow welfare as a top priority and are determined to find a better housing environment that enhances the overall well-being of the sow.

Sow Group Housing Systems

There are a variety of group systems for gestating sows using several feeding methods: floor, trickle, stalls and electronic sow feeding, says Harold Gonyou, Prairie Swine Centre, Saskatoon, Canada.

Floor feeding is a simple, inexpensive system, which controls feed intake but doesn't provide for individual control, and encourages competitive behavior favoring dominant animals.

The goal is to sort sows into groups with similar requirements and levels of competitiveness to even out feed intake. However, creating uniform groups in pens will often increase aggression, Gonyou explains.

New concepts in floor feeding at the University of Guelph involve larger group sizes, multiple feedings and providing protection through a series of separating partitions in the room.

Gonyou says the floor feeding system works best when combined with confining sows for four weeks in individual stalls post breeding. Sow uniformity in stalls should precede their move into groups.

Goals of short feeding stalls and trickle feeding systems are to provide protection for head and shoulders of sows while eating and to ensure that each sow has access to equal amounts of feed.

Single-drop feeding systems encourage fast-eating sows to steal feed. Trickle feeding provides feed at the rate of the slowest-eating sow and thus doesn't allow feed to accumulate and to be stolen. There are questions, however, whether improved protection provided by short feeding stalls and trickle feeding are worth the extra cost and space, he says.

In an Australian study, sows were fed in a cafeteria system where several sows “time-share” 14 sq. ft. of feeding space. This system worked well and produced less lameness, provided there was proper management and early treatment of problems.

Electronic sow feeders (ESF) at the Prairie Swine Centre provide control over individual feed intake, Gonyou says. When age groups are mixed, younger sows tend to use the feeders later in the feeding cycle after older sows have eaten. Overcrowding ESF stations will result in subordinate sows eating less often, he cautions.

ESF pens have experienced lost collars or tags and vulva biting when sows exit the feeding stalls. Gonyou stresses for ESF to work, equipment must be properly maintained and animals correctly trained.

In studies of sows in ESF systems at Prairie Swine Centre, keeping sows in individual stalls for five weeks after breeding (before mixing) improved farrowing rate 2-6% in first and second-parity sows, respectively, but produced minimal improvement in farrowing rates in mature sows.

Moving sows into the ESF system post-embryo implantation produced modest improvements in the number of live piglets produced in sows (all parities), based on 100 sows bred.

Gonyou observes when pre-implantation sows were placed into the ESF area, they were more aggressive than post-implantation sows, entered the feeder earlier in the day and avoided sleeping on the slotted floors.

Young sows in the ESF system experienced more scratches, entered the feeder later and slept on slotted floors more than older sows.

A University of Minnesota study in 2005 found 11 sows out of 206 culled for lameness in ESF systems vs. just one sow out of 176 culled for lameness when housed in individual gestation stalls.

The Canadian scientist stresses that feeding systems account for only some of the differences in results between the Minnesota and Australian studies. He says the differences relate more to the floor conditions, fully slotted vs. bedded in the two group housing systems, rather than to the feeding system (ESF vs. cafeteria).

Gonyou presented data on farrowing rates of sows gestated in stalls vs. groups from several researchers in the United States and Canada. The results indicated when group-housed sows were mixed before embryo implantation occurred, farrowing rates favored sows housed in gestation stalls. But group-housed sows mixed post-implantation showed almost no difference in farrowing rates vs. sows gestated in stalls.

Number born alive/litter in that same comparison of studies tended to slightly favor the ESF group-housed system for gestating sows, he reports.

Overall, it appears that both individual stall and group-housed systems for sow gestation can perform equally well, provided management and equipment are optimized to control problems, Gonyou says.