Space Allowance

Ensuring adequate and appropriate space allowance is an important part of planning your group sow housing system. Space allowance is one of the many considerations you must take into account to ensure a proper balance between welfare of the sows, herd productivity and economics associated throughout the conversion process.

The Code of Practice for the Care and Handling of Pigs

Minimum floor-space allowances recommended by the Code for grouped sows

Gilts
15-18 ft2 (1.4-1.7 m2), partially slatted
16-20 ft2 (1.5-1.9 m2), deep bedded

Sows
19-24 ft2 (1.8-2.2 m2), partially slatted
21-26 ft2 (2-2.4 m2), deep bedded

Gilts and Sows
18-23 ft2 (1.7-2.1 m2), partially slatted
20-25 ft2 (1.9-2.3 m2), deep bedded

It is strongly recommended that more floor space be allowed per animal in order to prevent aggressiveness among the sows in the group. This is particularly important in systems where there is competition for feed (floor feeding and shoulder stalls).

Ensuring adequate and appropriate space allowance is an important part of planning your group sow housing system. Space allowance is one of the many considerations you must take into account to ensure a proper balance between welfare of the sows, herd productivity and economics associated throughout the conversion process.

Competitive Feedings Systems

The floor space allowance for floor fed sows should be fairly easy to define in terms of productivity, incidence of injuries and level of aggression. The system is essentially an open pen with the condition that sufficient solid floor area is provided for feeding. However, few studies have examined the question of floor space allowance. One such study, by Sequin et al (2007), reported no advantage in any of these measures among space allowances starting at 2.3 m2/sow (24 ft2) and going up to 3.2 m2/sow (34 ft2). Salak-Johnson and coworkers (2007) reported problems at 1.4 m2/sow (15 ft2) compared to 2.3 m2/sow (24 ft2), but did not examine any intermediate levels. From these studies we know that 1.4 m2/sow is not enough and 2.3 m2/sow is sufficient; but there is a large range in between that has been poorly researched.

Mountain Vista. The sows lie in all directions.
Mountain Vista. Sleeping patterns are different in each group. Note new slat replacement in flooring. Over 10% of the original slats needed to be replaced.

If we look to grower/finisher pigs, who are also housed in open pens, there are detrimental effects on productivity below a space coefficient of k=0.034 (Gonyou et al., 2006) and changes in lying posture (indicative of decreased comfort) when k drops below 0.038 (Averos et al., 2010). Using weights from our facility for females near the end of gestation, gilts are observed at 220 kg and mature sows (3+ parity) at 310 kg. Applying the k values given above, gilts require between 1.24 and 1.39 m2/gilt (13 to 15 ft2) and sows between 1.56 and 1.74 m2/sow (17 to 19 ft2). The European Union specifies increased amounts of floor space for gilts (1.6 m2/gilt; 18 ft2) and sows (2.3 m2/sow; 24ft2) (Mul et al., 2010).

Additional research is required on floor space allowances in the range of 1.4 to 2.3 m2/sow (15 to 24 ft2). Until further research has been conducted, 1.4 – 1.6m2/gilt (15 – 18 ft2) and 1.7 – 2.3 m2/sow (19-24 ft2) is the suggested amount of fl oor space. It is necessary there is suffi cient solid fl oor area to feed sows without excessive aggression.

Non-Competitive Feeding Systems

  • If pen layouts are well designed, ESF systems can operate well at space allowances of 18-20 sq/ft per sow. However, aggression and skin injury scores can be reduced by providing more space (Remience et al., 2008)
  • The shape of the pen may help in allowing sows to avoid one another, and flee from a fight. Rectangular pen shapes appear to be more use than square pens and in allowing sows to avoid one another, pen shape could play a more important role than space allowance (Barnett et al., 1993).
  • One of the most evident to operation managers is that sows in large groups (over 40 animals) require less space per animal than those in smaller groups. The EU recommendations are that the standard recommended space allowance should be increased 10% for groups of 6 or fewer animals, but can be decreased by 10% when group size is of 40 or above, animals. (Council Directive, 2001).
Moffet Farms. One of the bedroom sleeping areas full of sows. Water drinkers are on the outside of the bedroom pens.

Free-Access Stalls

There is limited research data on the amount of space required per sow for free access stall systems. Leaving how much space is needed up to estimation, but in this regard the system is more complex than most other group housing. Free access stalls can be considered as having two parts: the feeding stall and the loafing area. Feeding stalls are generally designed to accommodate the animal for both feeding and resting. In order to allow large sows to rest comfortably in the stall, they are provided with a minimum of 0.60m (24 in) width, and 2.10 m (7 ft) length for a total of 1.3 m 2 (14 ft2) per sow (Nielsen, 2008). Comparatively, cafeteria systems, in which the sow only uses the stall only for feeding, a narrower and shorter stall that is wide enough for her to stand in but not wide enough to lie down can be used. The ‘I’ configuration, with only a slatted floor between two rows of stalls, in seen as the minimum loaf ng area. It is generally 3 m (10 ft) across to facilitate sow movement, which provides an additional 0.9 m2 (10 ft2) per sow when using 60 cm (24 in) stalls. This provides sufficient area for approximately 50% of the sows to use at one time (assuming a need for 1.7 m2 or 19 ft2 per mature sow), but it is unlikely that 50% of sows would be in the loafing area at once, in particular as slatted floors are relatively uncomfortable and discourage sows from using the loafing area. For producers who simply want to provide sows the opportunity to leave the stalls, the ‘I’ configuration with about 2.2 m2 (24 ft2) per sow would be sufficient.

HyLife-Rosco Farm Gestation area gilts accessing feeders

There is limited research data on the amount of space required per sow for free access stall systems. Leaving how much space is needed up to estimation, but in this regard the system is more complex than most other group housing. Free access stalls can be considered as having two parts: the feeding stall and the loafing area. Feeding stalls are generally designed to accommodate the animal for both feeding and resting. In order to allow large sows to rest comfortably in the stall, they are provided with a minimum of 0.60m (24 in) width, and 2.10 m (7 ft) length for a total of 1.3 m 2 (14 ft2) per sow (Nielsen, 2008). Comparatively, cafeteria systems, in which the sow only uses the stall only for feeding, a narrower and shorter stall that is wide enough for her to stand in but not wide enough to lie down can be used. The ‘I’ configuration, with only a slatted floor between two rows of stalls, in seen as the minimum loaf ng area. It is generally 3 m (10 ft) across to facilitate sow movement, which provides an additional 0.9 m2 (10 ft2) per sow when using 60 cm (24 in) stalls. This provides sufficient area for approximately 50% of the sows to use at one time (assuming a need for 1.7 m2 or 19 ft2 per mature sow), but it is unlikely that 50% of sows would be in the loafing area at once, in particular as slatted floors are relatively uncomfortable and discourage sows from using the loafing area. For producers who simply want to provide sows the opportunity to leave the stalls, the ‘I’ configuration with about 2.2 m2 (24 ft2) per sow would be sufficient.

However, if the intent is to provide a more comfortable loafing area, in order to encourage sows to use it for an extended period, both quantity and quality of space should be increased. In order to allow all sows to use the loafing area simultaneously, approximately 3.0 m2 (33 ft2) of space is needed for both the stall and loafing. To achieve this level of use, the loafing area would have to be more comfortable than the stall, requiring solid floor and bedding (or rubber mats).

The cafeteria system, in which several groups of sows share a bank of feeding stalls, has the potential to reduce space needs. If six groups of sows share a set of ‘feed only’ stalls, the stall requirement is less than 0.2 m2 (2 ft2) per sow. Providing a loafing area of 1.7 m2 (19 ft2) per sow would result in 1.9 m2 (21 ft2) per animal for the stall and loafing area combined. However, a cafeteria system also includes extensive alleys to move sows to and from the feeding stalls. Some of the space savings would be lost to these alleys.

Even at its minimum, a gated stall system requires more space than most other group housing. Achieving high usage of the loaf ng area would require even more space. The high space requirement is the greatest drawback of gated stalls, and producers should consider using low-cost buildings for this system.