By the end of 2012, 9 states in the United States imposed bans on individual stalls for pregnant sows. As a result, pig producers in those states must develop alternative methods for housing pregnant sows. A report from the West Central Research and Outreach Center of the University of Minnesota, Morris, describes the well-being of sows housed in pens retrofitted from gestation stalls. The study was published in the December issue of the Journal of Animal Science.
The goal for the study was to evaluate the performance of sows housed in retrofitted pens without reducing sow inventory from when gestation stalls were used. The study was conducted on a 5,000-sow commercial breeding-to-weaning farm in North Dakota.
Large and small pens for group housing pregnant sows were retrofitted from individual gestation stalls. Each large pen was 5.5 × 7.3 m in size and housed 26 sows, and each small pen was 5.5 × 1.7 m and housed 6 sows. Floor space allowance was approximately 1.5 m2 per sow in the large and small pens. A total of 338 sows were assigned to large pens, 156 sows to small pens, and 325 sows to individual stalls (2.1 × 0.55 m; approximately 1.2 m2 per sow) that served as controls.
The results of the study indicate that sows housed in pens weighed less at day 109 of gestation than sows housed in stalls. In addition, during the 74-day period of gestation that was studied, sows in large pens gained less weight than sows housed in small pens or stalls. However, sows housed in large pens lost less weight during lactation than sows housed in gestation stalls.
Throughout the study, sows were removed from the housing treatments for reasons including abortion, poor milk production, low body condition, locomotion problems, injuries from fighting, death or euthanasia, prolapse, prematurely weaning the litter, savaging piglets, and sickness that was not responsive to treatments. The sow removal rate was least for individual stalls (9.2%), while removal rate was 15.5% for large pens and 11.7% for small pens. Sows housed in large pens recorded the greatest number of removals for injuries from fighting (10 of 53 removals) and for poor reproduction (13 of 53 removals).
The results of the study reveal that it will be difficult to maintain performance of the same inventory of sows within a barn of fixed size if gestation stalls are converted to pens. In addition, greater space requirements are necessary to group-house sows in pens. As a result, fewer sows can be raised during a period. However, the fact that sows in this study were first raised in a gestation-stall system and farm workers were not experienced with group housing might have affected the results.
The study is titled “Performance and well-being of sows housed in pens retrofitted from gestation stalls.” It can be found at journalofanimalscience.org.
Y. Z. Li
West Central Research and Outreach Center
University of Minnesota, Morris, MN