April 19, 2007
AMES, Iowa - Keeping sows in individual stalls during pregnancy is coming under increasing scrutiny. Smithfield Foods plans 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 said it wants to reduce or eliminate the amount of pork it buys from companies that use them. The stalls have been banned in Florida, Arizona and 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.
"We found reproductive performance can be maintained or enhanced in well-managed group housing systems for gestating sows, such as deep-bedded hoop barns, without increasing labor," said Mark Honeyman, animal science professor and coordinator of Iowa State'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 the hoop barns gave birth to more live pigs per litter than sows gestated in confinement stalls.
Peter Lammers, graduate research assistant, said 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 the 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 said. "Because the hoop barns are a lower cost shelter, we can allow each sow more space. Also, the feeding stalls allowed us to 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 agricultural 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.
"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 percent reduction," said Jay Harmon, professor of agricultural and biosystems engineering.
The study found operating costs are similar for both systems. "But total costs per weaned pig are less for the system utilizing hoop gestation," said 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 percent less than the cost of a weaned pig from the individual stall confinement system."
Honeyman said 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 said. "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."
The project was supported by the Iowa Agriculture and Home Economics Experiment Station, the U.S. Department of Agriculture and the Leopold Center for Sustainable Agriculture.