Pork producers looking to switch from stalls to group housing for sows and gilts should scrutinize their options closely.

Most U.S. pork producers still house sows in individual confinement stalls. And there are many good reasons why stalls are preferred over group housing, says Don Levis, director of the Ohio Pork Industry Center, Columbus.

Individual stalls permit proper management of larger numbers of sows; physical aggression, especially during feeding, can be reduced; environment is controlled; more sows are housed in a smaller area; overall hygiene is improved; and herd reproductive performance is enhanced.

Levis says BanCruelFarms (www.ban cruelfarms.org) released an interpretation of 28 scientific papers alleging gestation stalls cause sow suffering.

But he says his experience suggests sows benefit from stalls.

“When I go on farms where there are both stalls and penned gestation, there is consistently a 3-5% difference in farrowing rate in favor of stalls,” says Levis. “And litter size is always a little bit less in group housing.”

Some group sow housing operations wean sows into stalls for 35-40 days, then turn them out into group pens.

Levis has seen problems with group sow housing systems. “In every group system I've seen, whether it be 20 sows or 300 sows in a pen, I can always find a few sows that are really in a high-risk situation. For group housing to work, I think producers are going to have to rethink a lot of management aspects.”

Group Housing Limitations

Levis, in a presentation for the fall Leman Swine Conference in St. Paul, MN, says producers may not be ready to switch to group sow housing.

“Pork producers who house sows in groups manage their dry sows in a group-penning situation without an abundance of scientific evidence to support their management practices.

“Pork producers need to carefully evaluate whether procedures recommended for the design of facilities and management of group housing systems will work for their operations,” he says.

When switching to group housing, staff must focus on identifying and enhancing the welfare of non-competitive sows.

Aggressiveness in group-housed sows can't be stopped because it stems more from sow personality than housing type.

Also, productivity is unpredictable with different stable or dynamic sow groups, where sows are moved in or out periodically.

Proper space requirements for group systems haven't been adequately researched to take into account physical needs and space to act out normal behavioral patterns, says Levis.

Space/sow varies widely in group systems. Housing systems that feed on the floor average 16-24 sq. ft./sow. Systems with individual stalls for feeding and resting provide 24-40 sq. ft./sow. Systems with electronic sow feeders without bedding have 18-32 sq. ft./sow.

The Danes have developed a system that provides 37.1 sq. ft./sow (Figure 1). The T-pen provides 30 sows/pen with individual, lockable feeding stalls; a 14-in.-wide feed trough; solid slotted feeding stall floor; mechanical feeding system; and solid floor bedded resting area.

Number of sows/pen needs to be researched. Currently, the number is determined by the feeding program; sow numbers to fill all-in, all-out farrowing rooms; breeding group; and pen size.

The number of sows/pen ranges from five to 200 head. “Most likely, the establishment of large social groups of sows in an appropriate size pen allows sows to avoid or flee from physically aggressive sows. But the speculation that large social groups of sows reduce physical aggression has not been scientifically evaluated,” observes Levis.

Five Group Sow-Feeding Systems

  1. Floor feeding has been documented to produce the most aggression in the first 30 minutes of feeding.

  2. Group feeding with non-locking individual feeding stalls allows freedom of movement in a large pen and sows are fed on the floor or in a trough.

  3. Group feeding with or without shoulder barriers is a way to possibly eliminate dominant sow aggression. This system features trickle feeding (about ¼ lb./minute) to keep sows in small groups “biologically fixed” in a feed space.

  4. Group feeding with locked, individual stalls is a European design used for a variety of management practices.

  5. The electronic sow feeding system allows sows to be group-housed but fed individually, says Levis.