- Regardless of the housing system, sow barn managers and caretakers should work to optimize their barn’s system.
- Proper design of facilities is an important start, but does not guarantee a successful operation.
- Effective stockmanship is crucial to making the facilities operate properly and ensuring sows are comfortable and productive.
Pork producers are encouraged or mandated to stop using individual gestation stalls and start using group sow housing. Unlike stalled systems, there isn’t a standard, well-understood template for group housing systems. A lot of factors play a role in setting up a system that works best for your farm including:
- Pen layout
- Flooring type
- Feeding system
- Nutrition program
- Grouping strategy
- Timing of grouping
- Pig flow
- Husbandry skills
As a result, it’s hard to accurately predict the success of any one group housing system. There are examples of good and bad transitions. Focus on these key features to increase your chances of success with group sow housing.
- Floor space allocation for sows
- Feeding plans to control changes in sow body condition
- Plans for managing sows in dynamic groups, and knowing how to mix sows
- Stockperson skills and ability to manage groups
Floor space allocation
It’s hard to establish an exact floor space allocation for sows to optimize reproductive performance and welfare. Space allocation depends on size or age of the sows, feeding system, group size and season.
The space occupied by a standard gestation stall and half of the aisle behind the stall is about 16 square feet. Most studies suggest this amount of space is inadequate for group-housed sows. In general, more space decreases aggression between sows and related injuries. It also increases farrowing rate (see Table 1).
Table 1. Effect of floor space allowance during gestation on litter size
|15 sq. ft./ sow
|24 sq. ft. / sow
|35 sq. ft. / sow
Increasing the floor space leads to an increase in building costs. Thus you won’t want to provide sows more space than they need. Increase floor space at least 10 to 20 percent when moving sows from individual stalls to groups. At a bare minimum, you must increase floor space from 16 square feet (stall size) to 18 to 19 square feet.
Group size affects proper floor space allocation. If group size is small (fewer than 10 sows), you should increase floor space allocation by 10 percent because there’s less total free space available in the pen. Free space is the area in a pen that a sow’s body doesn’t physically occupy.
If group size is large (more than 40 sows), you can reduce floor space allocations by 10 percent because there’s more free space.
Feeding to control changes in sow body condition
It can be hard to control sow body condition and weight gain among a group. Selecting a good feeding system is key.
Noncompetitive feeding systems allow sows to eat their daily feed without their penmates impeding. This limits competition and aggression between sows. Noncompetitive feeding systems include electronic sow feeding systems (ESF) and free access stalls.
These systems have higher equipment costs than competitive systems. You also must train your sows how to use ESF feeders or free space stalls.
In ESFs, a computer reads an electronic identification tag on a sow as it stands in the protected feeder. The computer then feeds the sow her respective diet. The feeding station is fairly compact and occupies little floor space.
Free-access stalls allow sows to eat their daily feed allotment without pressure from other sows, but requires a lot of floor space. Feeding various amounts of feed to penmates is harder with this system. Any sow can enter any available once the feed drops.
Competitive feeding systems don’t protect sows from other penmates during feeding. Dominant sows can push other sows away and eat their feed. Because sows are typically limit-fed in gestation, there’s almost always some competition and aggression around feeding time.
Competitive feeding systems have a higher chance of undesired variation in body weight and backfat depth of sows at farrowing. Grouping sows uniform in age and weight is key to success. You may need to provide housing accommodations for fall-out sows that don’t adapt to the feeding system.
Competitive feeding systems have a lower equipment cost than noncompetitive feeding systems.
Competitive feeding systems include
- Floor feeding: requires feed drops and a solid portion of floor
- Partial feeding stalls
- Trickle feeding systems
Partial feeding stalls
The partial stall system is a form of floor feeding. Feed gets dropped in the front of a stall. These stalls have sides that may only extend to the shoulder or mid-body of the sow. This design prevents dominant sows from pushing timid sows away. But dominant sows can still back out of one stall and displace another.
Trickle feeding systems
Trickle feeding systems provide feed in small amounts at the same rate that sows can eat feed. The idea is that sows are more likely to stay in one feeding location because they know more feed will be dispensed shortly. Producers often use trickle feeding in combination with partial stalls.
Managing sows in dynamic groups
Effective competitive feeding systems require grouping sows uniform in age and body weight. Dynamic or static groups are two main approaches to keeping sows in a group housing system.
Dynamic groups have more than one breeding group housed in a pen together. As sows in one breeding group move out for farrowing, a new recently mated sow group moves into the pen. This approach is flexible and uses building space efficiently. But sows are exposed to some aggression throughout pregnancy each time a new group of sows enters.
In static groups, each pen houses only one breeding group of sows. Sows experience one bout of mixing at the start of gestation. If a sow recycles or is removed, no replacement sow is introduced. So efficiency of pen space use may suffer with static groups.
In static and dynamic groups, you’ll have to mix sows that are unfamiliar with each other. Mixing causes fighting that’s needed to establish social rank among sows. Fighting can harm sow performance and welfare. Thus you must properly manage mixing for successful group housing.
When should you mix sows?
If possible, don’t mix sows until at least 30 days after mating, when you have confirmed pregnancy.
Mixing sows creates stress. Ideally you should mix sows after the embryos attach firmly to the uterus. Embryos float inside the uterus for the first 18 days of pregnancy. Afterwards they attach to the uterus (called implantation) and become more robust and resistant to stress.
Mixing sows post implantation compared to preimplantation can improve farrowing rates (Table 2).
Table 2. Effect of mixing before (pre) or after (post) implantation on sow performance
|Farrowing rate, %
Stockperson skills is an important role on sow farms. These skills are slightly different for group housing than individual pens.
Stockpeople must employ an “animal-directed” approach to caring for group-housed sows. They need to understand what’s normal and what’s abnormal sow behavior. Stockpeople must then recognize the cause of abnormal behavior to properly correct it.
Knowing normal sow behavior can help stockpeople perform management tasks more efficiently, and with less stress on sows and workers. For example, recognizing when it works best to vaccinate sows in group housing. Stockpeople may notice after dropping feed, the sows focus on eating. Thus they pay little attention to the stock person or react to the injection.
Likewise, checking for sows in heat may be more efficient and effective when group-housed sows are usually resting and inactive. During this time, the sow in heat is more likely to be up and more active than her penmates, and she will stand out and be easier to identify.
Stockpeople must be open-minded about group housing and be willing to learn new skills or relearn old ones. Moving slowly, deliberately and quietly around sows increases the bond and trust between sows and their caretakers. This trust will make it easier to move sows and work around them.
Research shows trust can also improve reproductive performance of sows. When sows trust their caretakers, tasks like pregnancy diagnosis in pens can be fairly easy, because sows allow workers to approach with the ultrasound unit.
Sows have freedom to move in walking barns with pens. Thus the sows won’t always be in the same place each day as they are in stalled systems. This means workers must walk the barn in the same pattern each day but can start the pattern at a different spot each day. Doing this will allow them to see a given pen of sows at different times of the day. As a result this improves their chances of finding disadvantaged sows that need attention.
Evaluate sows for body condition, health, behavior and attitude.
Ensure the equipment (feeders, feeding stalls, gating, flooring, waterers, etc) in each pen is working properly and will not injure sows.
Monitor the air quality of the room or barn and the capacity of the manure storage system and adjust it as necessary.
Reviewed in 2018