So you are exploring group sow housing. Whether this decision is based on market demand, state legislation or personal preference, there are several things to consider when choosing which system best meets your needs.
The first decision is what type of feeding system to use. Will it be small pens of 8-12 floor drop, small pens of 8-12 stanchion feeding, free access or Electronic Sow Feeding? There are pros and cons to each category of feeding systems.
Retrofitting a barn, particularly if it is partially slatted, can influence these decisions. Small pen floor drop or stanchion feeding can sometimes be easier to adapt than larger pen systems. The floor drop and stanchion systems by design create competition within the pen for feed. Free-access systems enable the sow to be in a stall or in a pen, but free-access systems have a higher price tag and require extra square footage per sow compared to floor drop, stanchion or ESF.
For producers seeking true individual nutrition within a group setting, ESF is the only solution. These systems allow the computer to feed each sow on an individual basis and can paint mark and sort sows out for specific tasks. Generally, pen size is much larger than the stanchion or drop feeding systems, consisting of 60 to 300 sows per pen and single-feeder pens to multiple-feeder pens.
Once you have chosen ESF as your feeding type, the next step is to consider how to mix the sows. One option is to keep the breeding groups intact and establish a static sow flow. This normally consists of medium-sized pens of 60 to 80 with one feeder per pen. The other option is to spread breeding groups out over several pens. This system, called a dynamic flow, usually consists of pens with more than one feeder containing 150 to 250 sows, although single-feeder pens can also be flowed dynamically.
Both systems present pros and cons. The biggest advantage to a static system is the ability to visually evaluate the sows and determine if they are in the right stage of pregnancy and body condition for a particular week of gestation. Also, tasks can be easier to manage in this type of system. In other words, all of the females in a particular pen must have the same tasks performed in the entire pen — for example, the entire pen gets a pre-farrowing vaccination.
The biggest advantage to a dynamic system is utilization of space. In a static system, where the group is commingled one time, you are not able to put one or two more sows back into the pen without negative consequences. Therefore, if you have a sow fall out of the group, you cannot replace her and that space is lost. With a dynamic system, you are continually grouping sows, so if a sow is removed prior to farrowing, another can be added into the pen when you are re-grouping it.
Of course, the opposite is true regarding the disadvantages of each system. In a dynamic system, several breeding groups are housed in one pen. This makes it more difficult to visually assess sow conditions. You will also not treat all the sows in a pen at the same time. Automatic paint markers and sorters can be very beneficial in performing these tasks, but do not aid in the visual assessment of the sows.
Another potential advantage to the dynamic system is the theory that sows actually are in conflict less than in a static pen. Proponents of dynamic systems observe only the sows added to the group establish a pecking order, whereas the sows that are already housed there have established their hierarchy and do not confront the newly penned sows.
There are options for laying out dynamic pens. Some production systems use a more traditional rectangular pen with the feeders along the alley. This design maximizes the throughput of the ESF feeders; some production systems are feeding close to 80 sows on one feeder. The industry is also seeing pens designed with the feeders grouped together. Sows are then funneled through a common aisle that can have a single sorter. This system allows more sows to utilize a sorter and boar station, but limits the number of sows per feeder to about 55.
Finding a design that works for you is important in your decision-making process. Certain feeders perform better in certain designs, while some perform well in any design and are flexible to meet your needs.