Introduction

With two states banning the use of individual stalls for gestating sow housing and the announcement from Smithfield Foods that their production systems will SLOWLY move toward group housing of gestating sows, there is much interest in alternative sow housing systems. It should be said though, that sows housed in individual stalls allows for adequate management of the sow and that there is no welfare advantage for sows housed in groups versus those housed individually in stalls (AVMA Task Force Report. 2005). Nonetheless, different forms of group sow housing are being investigated as possible alternatives to individual sow housing. This article summarizes a report (Lammers et al., 2007) that compared sows that were housed individually during gestation to those that were housed in groups in Hoop Buildings during gestation.

Study Design

This study was conducted near Atlantic IA, at the Lauren Christian Swine Research and Demonstration Farm from March, 2001 to September, 2003. Sow genetic background was ½ Yorkshire: ¼ Hampshire: ¼ Landrace. Sows farrowed and lactated in individual conventional stalls in an environmentally controlled building until weaning. After weaning sows were placed into slatted floored pens in an environmentally controlled building and mated in a common breeding facility and then allocated to one of two gestation housing treatments. All females (weaned sows, gilts, recycles, etc) which had been mated within 9 days after a group of sows were weaned constituted a group (up to 32 females). Sows allocated to the gestation stall treatment were kept in 2’ x 7’ ft. stalls, in an environmentally controlled building, after mating and throughout gestation. Sows allocated to the group housing treatment, were placed into stalls after mating and then moved into a hoop structure, within the 9 day span mentioned previously. Sows housed in groups were allocated 37 sq. ft. of space per female, of which 25.4 sq ft. was the bedded area and 11.6 sq. ft. was used for feeding stalls. For the group housing treatment, there was a feeding stall for each sow. Feeding stalls were latched while a sow consumed its feed but remained open during non-feeding times. All gilts were gestated in stalls after mating and then placed into one of the two gestation treatments after weaning their first litter and returning to estrus.

All sows were fed 4.5 lb/day during the first 2/3 of gestation and then increased to 6 lb/day for the final 1/3 of gestation. From November through March, feed fed to sows in gestation stalls was increased 5% while sows in groups in Hoop Barns had their feed increased 25% to offset increased thermal demands for winter.

Results

Sows which gestated in groups in Hoop Barns weighed more at 110 days of gestation (~ 9 lb) and were fatter (~0.05 inch) than sows which gestated in stalls. Sows which gestated in groups in Hoop Barns lost more backfat during lactation (0.02 in) but had similar weight loss while nursing. Though weighing more and being somewhat fatter at the beginning of lactation, sows which gestated in groups in Hoop Barns had similar lactation feed intake to those sows housed in individual stalls.

There were few differences due to gestation housing treatment for reproductive performance. Sows housed in Hoop Barns did have more total pigs born than sows which gestated in stalls (11.7 vs 11.3, respectively) and subsequently had more number born alive (10.9 vs 9.7, respectively). After farrowing, litter size was standardized across treatments and no difference in number weaned was observed between sows which had gestated in group or individual housing (avg. 8.85 pigs weaned). Sows which gestated in Hoop Barns did take longer to return to estrus after weaning than did sows which gestated in individual stalls (6.0 vs 4.3 days, respectively).

Conclusion

Sow which gestated in groups in a Hoop Building did farrow more pigs but took longer to return to estrus that individually housed sows. Sows gestated in groups in Hoop Buildings were offered more feed during the winter but were just slightly fatter and heavier at farrowing. Overall this demonstrated that sows housed in groups can be managed to obtain similar reproductive performance (i.e. littersize) in comparison to sows housed individually in an environmentally controlled building.

Final Thoughts

The results of this study should be taken at face value without further generalization. Sows which are put into groups quickly after mating (2-5 days) can achieve similar reproductive performance as individually housed sows. In addition, gilts were not placed into group housing with sows which does add to the complexity of the interpretation of the results. Bred gilts included into groups with sows can be at a greater risk of being dominated by older and heavier females which can be detrimental to their reproductive performance and welfare. Furthermore, though Hoop Buildings may be cheaper in construction costs than environmentally controlled buildings with individual sow housing, feed costs per sow may be higher, due to increased feed allocation during winter, as was demonstrated in this study. Group housing of gestating sows can be done in a satisfactory manner; however, several factors including, feeding method, day of gestation after mating when grouped, parity distribution, housing type and square footage allocated must be considered when developing a group housing system.

Literature Cited

AVMA Task Force Report. 2005. A comprehensive review of housing for pregnant. 2005. J. Amer. Vet. Med Assoc. 227: 1580-1590.

Lammers, P.J., M.S. Honeyman, J.W. Mabry, and J.D. Harmon. 2007. Performance of gestating sows in bedded hoop barns and confinement stalls. J. Anim. Sci. 85:1311-1317.

September 2007