Wallace's Farmer, IA
04-26-07
ISU Studies Alternatives to Sow Stalls
Compiled By Staff
Keeping sows in individual stalls during pregnancy is coming under increasing
scrutiny by the public, by restaurant chains and by animal welfare organizations.
Smithfield Foods, the nation's largest pork producer and processor, has
announced its plan to phase out the use of gestation stalls. Burger King
announced it will stop buying pork from suppliers who use the stalls, and
McDonald's says it wants to reduce or eliminate the amount of pork it buys from
companies that use them. The use of gestation stalls has been banned by state
law in Florida and Arizona and by the European Union.
Researchers at Iowa State University have been studying group housing in
hoop structures as an alternative to gestation stalls. They say the results are
encouraging, in terms of both sow performance and economics.
Produce pigs at lower total cost
"We found reproductive performance can be maintained or enhanced in wellmanaged group housing systems for gestating sows, such as deep-bedded hoop
barns, without increasing labor," says Mark Honeyman, animal science professor
and coordinator of ISU's Research Farms. "We also found group housing may
produce pigs at a lower cost than individual gestation stalls in confinement
facilities. And the pigs may qualify for expanding niche pork markets."
For two-and-a-half years, the effects of two gestation housing systems on sow
and litter performance were evaluated in a project at an ISU-managed research
farm owned by the Wallace Foundation for Rural Research and Development in
southwest Iowa. One system involved individual gestation stalls in a
mechanically ventilated confinement building with a partially slatted floor and a
manure flush system. The other system involved group pens with individual
feeding stalls in deep-bedded, naturally ventilated hoop barns.
Researchers tracked 957 litters from 353 sows. They found sows in hoop barns
gave birth to more live pigs per litter than sows gestated in confinement stalls.
Why did sows in hoop barns do better?
Peter Lammers, graduate research assistant, says one reason sows in the two
hoop barns may have done better was the bedding and extra space for the sows.
"The presence of bedding and ability to huddle together or maintain distance
between animals may have enabled the sows gestated in hoop barns to have
more control over their thermal environment," he says. "Because the hoop barns
are a lower cost shelter, we can allow each sow more space. Also, the feeding
stalls let us manage the sows as individuals, although they were kept in groups."
A related study compared the economics of the two sow gestation systems.
General contractors familiar with ag construction in the Midwest and suppliers of
equipment and materials were surveyed in January 2006. Those responses were
used to develop cost estimates per sow space.
With more experience, practice will evolve
"The estimated construction cost per gestating sow space for group housing in
hoop barns was $552, compared with $815 for individual confinement stalls - a
32% reduction," says Jay Harmon, professor of ag and biosystems engineering.
The study found operating costs are similar for both systems. "But total costs per
weaned pig are less for the system using hoop gestation," says James
Kliebenstein, economics professor. "And when the increase in the number of live
pigs produced per sow in the hoop barns was taken into account, the group
housing of gestation sows resulted in a weaned pig cost that was 11% less than
the cost of a weaned pig from the individual stall confinement system."
Honeyman says research has shown group housing systems may not require
more labor per animal than individual gestation stalls, and in some cases may
require less.
"But the labor and skill sets needed for successful management of sows housed
in groups may be different," he notes. "Systems with individual gestation stalls in
confinement buildings are the result of decades of experience and refinement. In
the United States, using a bedded system for gestating sows in hoop barns is
relatively unfamiliar. With increased experience, management will evolve and
production may be enhanced." This project was supported financially by ISU,
USDA and the Leopold Center for Sustainable Agriculture at ISU.