Sow Gestation Facilities

During the past few years, there has been growing concern expressed by the public over the continued use of individual stalls in gestation or pregnant sow housing systems. In the United States, this has resulted in legislation by a number of states to ban individual stalls or pressure from retailers like McDonalds and Safeway (grocery food chain) to not purchase pork raised in facilities with sows housed in stalls during most of their pregnancy. These laws and policies have resulted in many of the large swine integrators and packers in the U.S. (Smithfield Foods and Hormel Foods) indicating that they intend to phase out stalls in company owned farms by 2017 or 2018.

Smithfield is the largest producers of pigs in the United Stateswith 838,000 sows or 14.4% of the December 1, 2011 breeding herd inventory (Freese, 2011). An estimated 75% of the roughly 6 million sows raised in the U.S. are housed in stalls, so the move from stalls to some type of group sow housing system will have a major impact on the pork industry in the next 5 to 10 years. The pork industry is primarily concerned with maintaining sow productivity or maximum pigs produced per sow per year during this transition. The management requirements of people working in these group sow facilities are also of concern as is the animal well-being or welfare.

The type of group sow housing that will replace the gestation sow stalls in many U.S. facilities is still not known. There are a number of different options of group sow housing systems that are under study and being implemented on farms. Selection of these group sow systems by integrators and individual producers also depends if it is a remodeling or renovation of an existing barn or the construction of the new facilities. Housing decisions will be made based on limited experience and some research although much will be done based on economical rather than biological reasons. 

For many of the group sow housing options being discussed, the general consensus is to keep recently bred sows in individual stalls for approximately the first 30 days to insure embryo implantation. Reproduction failure has been reported in sows that have been placed immediately in groups after being weaned to those that have been kept in individual stalls (Munsterhjelm, et al., 2008). A recent study (Hopgood, et al., 2011) compared sow performance where sows were mixed or placed in groups after 3 to 7, 13 to 17, and 35 to 50 days post weaning to sows kept in individual stalls for the entire gestation period. Once mixed together, grouped sows were housed in a fully slatted floor pen with an electronic sow feeder (ESF). This study was done at a commercial 6,000 sow farm with roughly 400 sows assigned to each of the three different grouped sow sets. The preliminary results revealed the sows in the first two groups, mixed after 3 to 7 and 13 to 17 days post weaning, did have significantly lower conception and farrowing rates compared to the stall sows while the grouped sows mixed after 35 to 50 days post weaning did not have significantly lower conception or farrowing rates than the stall sows. For these reasons, many of the regulations (EU) or agreements with retailers and processers will allow bred sows to remain in stalls for the first 30+ days before being placed in some type of grouped system.

Most studies that have compared sow performance between individual stall and group housing systems have shown that productivity is greater in the stalled systems (McClone, et al., 2004). The reasons why stall systems are more productive are that sows stay in the herd longer and thus produce more and higher quality piglets (Baidoo, 2012). Baidoo (2012) goes on to explain that sows in stalls do not engage in fighting and other dangerous behaviors and therefore do not suffer lameness and are more easily managed for health and nutrition.

A comparison study, by an integrator in Minnesota (Schwartz Farms), reported on production data collected over a three + year (39 months) period from two 5000 sow farms, one housing sows in standard gestation stalls and the other in groups of 135 sows per pen with two electronic sow feeders (ESF) per pen. Sow performance as measured by pigs weaned/mated female/year (PW/MF/Y) were higher in the stall system (25.7) compared to the ESF system (25.0) and sow mortality was higher in the ESF group barn, 7.0 vs. 5.8% (Schwartz, 2011). They also reported over 3 times the number of sows (653 vs. 205) culled for failure to conceive in the ESF group barn compared to the stall barn but failure to express estrus was more common in the stall barn (297 sows) than in the ESF barn (76 sows). Some non-biological differences were also reported;for the year 2010, nearly 1.5 hours more labor (8.29 vs. 7.82) per sow was needed to manage sows in groups compared to stalls. Economically, the ESF system required about 0.2 m² more floor space than the stall system. This translates to nearly400 m² more area for an ESF group sow barn that houses 5,000 sows compared to a conventional stall barn which translates to about 10 to 15 cents/weaned pig of additional costs for the group sow facility.

Another study (Ketchem and Rix, 2012)surveyed a large number of producers (509 farms with nearly 1,000,000 sows total) and compared three basic sow housing options: conventional stalls for the entire gestation period, Electronic Sow Feeding (ESF) where sows are held in stalls for 30+ days post breeding then placed in pens with ESF systems, and pens where the sows are again held in stalls for 30+ days postbreeding than placed in groups with a non-ESF feeding system. They selected farms with at least 3 years of production and prescreened farms to eliminate data variations from startup, repopulation, and disease influenced herds. Also, the distribution of the 509 farms between stalls, pens, and ESF were 368, 133, and 8 farms respectively. As found in previous studies, farms with conventional stalls where slightly more productive than farms with pens or ESF systems. The most commonly reported production metric or parameter is pig weaned/mated female/year, which for the stalls, pens, and ESF farms were 25.75, 24.86, and 25.59 respectively. The article also raised some key practical issues surrounding when buildings are converted from stall to pens or ESF systems, what needs to be done with sows in the transition, biosecurity issues during the move and how to adapt the management including training of current staff from stalls to group housing systems. 

As most people in the pork industry in the U.S. have acknowledged, the industry is slowly moving away from stall housing for sows to some type of group housing system. The question is what type of group system to select.The following group sow housing options were offered by Dr.Yuzhi Li, faculty member in the Department of Animal Science at the University of Minnesota,during one of several talks during a recent (May, 2012) Federation of Animal Science Societies(FASS) webinar which classified the options by the type of feeding systems used:

Floor feeding
Feeding stalls
Electronic Sow
Feeders (ESF)
Free-access stalls
Trickle feeding
Stall feeding station

The advantages and disadvantages for each of the options are discussed below in regards to how they control a sow's feed intake, the floor space needed, and how it deals with sow aggression. 

This is the simplest and lowest cost option available to producers, since it combines the feeding and resting areas for the group housed sows. Since a solid floor is needed this system is not compatible with slatted floors and liquid manure systems. Also, the only way to reduce sow aggression and control individual feed intake in this system is to reduce group size according to age and condition and even then this is limited. 

The use of full length feeding stalls greatly improves the individual feed intake for sows and can reduce sow aggression issues since timid sows can "hide out" in these feeding stalls during fights. Another advantage of this system over a floor feeding system is that this allows managers a place to hold sows if they need treatment or individual care. The largest disadvantage is that more total building space is needed per sow for other activities besides feeding. 

ESF systems have seen limited use in the U.S. during the last 10 to 15 years, but these systems can control individual sow feed intake quite well, assuming the technology works as planned. An ESF designed barn will require slightly more (10%) barn space than stalls and is compatible with both slatted (liquid manure) and solid floor systems. A major disadvantage is that a small percentage of sows/gilts (5 to 10%) cannot be trained to use the ESF units and there still is some sow aggression issues caused when sows must wait to access the feeder and sows making multiple passes through the feeder hoping to get additional feed. Also the investment plus the operating and maintenance costs are high and there is a need for skilled personnel to maintain the feeding unit itself and to keep the identification (ID) tags on the animals. 

The free-access stall system typically uses self-locking stalls where sows can enter and leave for simultaneous (at the same time) feeding. These systems do a reasonable job of controlling feed intake for individual sows and eliminating sow aggression during feeding. These can be used in both slatted and solid floor barns and like the common feeding stall option; sows can hide out in the stalls during fights and can rest there as well. Disadvantages of this system are increased costs of the selflocking stalls over simply feeding stalls and greater floor space per sow than the ESF system. 

A trickle feeding systems tries to match the rate of feed delivery with the eating speed of sows to control individual feed intake and reduce the aggression between sows during feeding. Most of the time, short or partial dividers separate the sows during feeding so there is less cost than systems using full length feeding stalls and less overall space is needed. The major disadvantage with trickle feeding is that sows who eat faster than others can still steal feed from neighboring sows that eat slower. This is especially a problem for large (> 30) groups of sows and/or where there are old and young sows in the same group. 

This system can be compared to a cafeteria where different group of sows are allowed to eat at the same set of feeding stalls. Each group is allowed access to the "cafeteria" over a short time period (generally 20 to 30 minutes) once a day. This can control the feed intake reasonably well for individual sows and is an efficient use of building space. The amount and quality of human labor needed to move sow groups is the largest disadvantage of this option. It is possible for both slatted and solid floor systems but only reduces rather than eliminates sow aggression during feeding. 

Sow housing systems in the United States and in some pig producing areas of the world are changing from stalls to various types of group housing systems due to societal concerns over animal welfare. No clear single alternative system to stalls seems to be emerging, at least in the United States. Feeding stall systems seem to be the single most common option of group housing systems. Choices in the types of group systems seem to depend if producers are remodeling or building new facilities, have staff willing and able to adjust to the management needed in the new systems, and are comfortable with the cost to build and operate the new group housing system. 

Baidoo, S.K., 2012. Image overrides stall's 'service'. Feedstuffs, June 4, 2012 issue. p. 15-16.

Freese, B. 2011. Top 25 U.S. Pork Powerhouses. Successful Farming Magazine, Nov. http://www.agriculture.com/uploads/assets/promo/external/siteimages/PorkPowerhouses2011b.pdf accessed June 19,2012.

Ketchem, R. and Rix, M. 2012 "Studying Gestation Housing Alternatives", National Hog Farmer magazine, May 15, 2012 issue. p. 44-47.

Hopgood, M., Greiner, L., Connor, J., Salak-Johnson, J., Knox, R. 2011. Effect of day of mixing gestating sows on reproductive fertility and animal well-being. Proceedings (CD, Vol 38) of the 2011 Allen D. Leman Swine Conference, University of Minnesota, College of Veterinary Medicine, St. Paul, MN. Sept 18-20, 2011. pp. 199 - 202.

McClone, J.J., von Borell, E. H., Deen, J., Johnson, A.K., Levis, D.G., Meunier-Salaun, M., Morrow, J., Reeves, D., Salvak-Johnson, J.L., Sunberg, P.L. 2004. Review: Compilation of the scientific literature comparing housing systems for gestating sows and gilts using measures of physiology, behavior, performance, and health. The Professional Animal Scientist, p. 105-117.

Munsterhjelm, C.,Valros, A.,Heinonen, M.,HcTlli, O.,Peltoniemi, OAT. 2008. Housing during early pregnancy affects fertility and behavior of sows. Reproduction in Domestic Animals. 43(5): p. 584-591.

Schwartz, M. 2011. A comparison of group-housed gestation and stalled gestation within a system. Proceedings (CD, Vol 38) of the 2011 Allen D. Leman Swine Conference, University of Minnesota, College of Veterinary Medicine, St. Paul, MN. Sept 18-20, 2011. pp. 207 - 210.