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Group Sow Housing: Decisions to Consider

04 July 2014

Michigan Pork Quarterly

Ronald O. Bates (State Swine Specialist at Michigan State University) and Beth Ferry (Extension Educator) address some of the decisions pork producers face when considering the change from individual stalls to housing sows in groups.


Pork producers in multiple states, including Michigan have legislative or regulatory mandates to house gestating sows such that they can turn around freely without impediment, lie down, stand up and fully extend their limbs. The implementation of this mandate will cause producers to house sows in groups during gestation. The change from housing sows in stalls to group housing is not just simply changing the penning. There are critical sow care and welfare, productivity and financial considerations to evaluate.

Pork producers that make this change must evaluate how their animal management and employee training program will change, what productivity differences may occur and how the initial capital costs as well as any changes in cost of production will ultimately affect their farm business.

This article will address some of the decisions pork producers face when considering the change from individual stalls to housing sows in groups.

Issues to Consider

Farms that change from housing gestating sows in individual stalls to housing them in groups have important, complex decisions to make. For the most part they can be categorised by the following:

  • What are the financial resources for the project?
  • What type of feeding/housing system will be used?
  • Will the present building shell be used or will additional space or a new barn be built?
  • Will the present feeding system be maintained?
  • What is the design specification for floor space allocation per sow?
  • What is the design specification for the number of sows per pen?
  • How will animal management and employee training change?
  • Will productivity change and if so, how will this affect subsequent cost of production and long-term profitability and viability?

Under each of these categories are many subcategories that will also have to be addressed. However, these points can provide the framework of putting together a transition plan from individual stalls to group sow housing.

This article will begin to address the first two items in the previous considerations. It must be understood however, that many of these topics are interlinked and as changes occur within one category, other changes must occur across these decision points. Subsequent Pork Quarterly articles will address other areas that must be considered when making the transition from stalls to group sow housing for gestating sows.

Financial Resources

Farms that consider this transition must be realistic in what the initial capital costs will be and productivity changes that may occur which could alter cash flow. As with any project of this type it is realistic to assume that there will be a period of time where cash expenditures will increase and earnings may be reduced. Farms that are in good equity positions should be able to work with their lender and develop a reasonable transition plan that would include cash flow assistance over the time period of remodeling/construction when expenditures could increase as well as some type of sensitivity analysis that would show how earnings could fall. This will help the lender understand how operating loans may need to change while the farm works through this transition.

Farms that are highly leveraged should evaluate their present financial position and determine what type of transition plan they can afford without worsening their position to a point of insolvency. This will be more challenging. There are tools available from the National Pork Board and Michigan State University that can assist in comparing the cost of transition of different housing systems. However, farms will need to have accurate and reliable quotes from companies that will provide the new equipment and complete the installation.

Feeding/Housing Systems

As pork producers consider what type of feeding and housing system to implement, many of the subsequent choices fall into place. This is a critical decision since once the type of system is chosen and installed; it can be difficult to change quickly. Several important topics should be reviewed when considering the available options;

  • Does the farm want sows to consume feed in a competitive or non-competitive system?
  • How much control does the farm want over the amount of feed offered to sows during gestation?
  • Can the system maintain a high level of sow care and welfare?
  • Will the system require more or specialised labour?
  • What is the management capacity of the farm staff to learn and manage the different systems of choice?

Non-competitive vs competitive feeding systems

Feeding/Housing Systems can be classified in multiple ways but typically they are classified as either Non-competitive or Competitive Feeding Systems.

The big difference between the two is that in Non-Competitive Feeding Systems, sows can eat their daily feed allocation without interference from other sows, while in Competitive Feeding Systems sows can interfere with each other while feeding. There are two primary non-competitive feeding systems, Electronic Sow Feeding and Free Access Stalls.

There are many versions of competitive feeding systems and typically they are classified as floor feeding, non-gated feeding stalls or trickle feeding.

Electronic feeding systems

Electronic feeding systems (ESF; Figure 1) is considered a 'big-pen' system with group size ranging from a low of 30 to 40 sows to high of 200 or more sows per pen group. Each ESF station can typically feed 50 to 80 sows and group size is typically a function of how many ESF stations will be placed into a pen. ESF allows management to specify the exact amount of feed to be offered to each sow per day. In addition, each day the ESF system will provide a report listing sows that did not eat their previous daily allocation. This can be an indication that a sow may be ill, injured or has lost her Radio Frequency Identification tag which indicates to the station which sow she is.

The ESF system can also be fitted with features that will mark a sow with a spray livestock marker for particular reasons (e.g. vaccination, pregnancy evaluation, etc.) as well as to sort sows out of the pen when finished eating (e.g. pregnancy evaluation, move to farrowing, etc). The ESF system provides the greatest control for feed allocation on a per sow basis. However, it is also felt that ESF requires a higher skill set to manage properly. This is due to a need for improved stockmanship and the ability to manage the feed station and repair it as needed. Often, support for station repair and maintenance can be supplied by the manufacturer through a service contract.

Typically a few small pens are maintained throughout the barn for compromised sows that may be lame, sick etc. It is not uncommon that compromised sow pens will make up five per cent, and sometimes more, of the total gestation space. Though the individual feed station is considered costly, often the cost per sow (including all penning, floor space, etc) is comparable to other group housing systems. Static or Dynamic Grouping can be used. In both cases standard operating procedures on putting sows together in pens should be developed to minimise fighting, injuries, lameness and culling.

Michigan State University
Figure 1. An example of sows housed in an ESF

Free access stalls (FAS)

Free access stalls (FAS; Figure 2) are typically considered to be a medium to large group system with the number of sows in a pen often dependent on how many different feed amounts are to be offered to gestating sows. FAS is a non-competitive feeding system that allows the sow to walk into an individual stall and the gate close and lock behind her. When she wishes to leave, she can back up and the gate will open allowing her to back out into the common space. Typically, the alley between the rows of stalls can range from six to 10 feet, but often it is eight feet.

The lay-out can vary. Typically there is a loafing area offset from between the stalls but it is not unusual that the only common area is the isle between the stalls. All sows within a pen are fed the same amount of feed since no one sow will always eat in the same stall. Therefore, if farms wish to have the flexibility to segregate sows by the amount of feed to be offered to each sow,

Allowing more fed to thin sows and less to heavier conditioned sows, sows will have to be sorted into pens dependent on the amount of feed offered. It is not unusual for compromised sows to be 'locked in' and not allowed out while being treated or recovering from an injury, as long as water is available within the stall. If water is not available within the stall, designated stalls within a pen may have water provided to be used for compromised sows, or a designated compromised sow pens should be available elsewhere in the barn.

Static or Dynamic Grouping can be used. In both cases standard operating procedures on putting sows together in pens should be developed to minimise fighting, injuries, lameness and culling. FAS are more expensive than a typical gestation stall due to the extra mechanical devises to allow for the self-closing and opening gate. This along with more space needed on a per sow basis, typically makes this system a higher cost option.

Michigan State University
Figure 2. An example of sows housed in FAS

Floor feeding

Floor feeding sows (Figure 3) in groups is just that, dropping feed on a solid portion of the floor and sows mill about consuming feed. This type of feeding and housing system is often used when sows are penned in small groups, typically no more than 20 sows per pen.

The solid portion of the floor that feed is dropped onto can vary. It can be a solid portion of the floor level with the slatted floor. It can also be a raised pad within the pen, along with other variations. The total amount of feed dropped is typically equal to the amount of feed that should be fed to any sow within the pen, multiplied by the number of sows in the pen.

For example, if you believed that sows within a pen should be fed 5 lbs. of feed per sow per day and there are five sows in the pen, then 25 lbs. of feed per day will be dropped to feed the sows. It is recommended that when floor feeding sows, sows should be penned in static groups. Floor feeding is typically considered an inexpensive system to install. However, feed wastage is a concern as well as increased levels of aggression due to fighting for feed which can lead to increased injuries, lameness and culling.

Michigan State University
Figure 3. An example of sows housed in a Floor Feeding System

Non-gated feeding stalls

Non-gated feeding stalls (Figure 4) , sometimes called 'short stalls' are a hybrid version of typical gestation stalls. The stall is typically 18 to 36 inches in length and separates feeding areas where feed drops are located, similar to what would be seen in a typical gestation stall barn.

The feed is housed in a feed box and dropped onto a solid area under the feed tube or into a feed trough. All the sows within a pen are offered the same amount of feed, since sows will not typically go to the same feeding location each time feed is dropped.

This type of feeding and housing system is often used when sows are penned in small groups, typically no more than 20 sows per pen. Sows should be penned in static groups. The cost of installation can be somewhat less than what a producer would expect when installing typical gestation stalls.

Michigan State University
Figure 4. An example of sows housed in a Non-gated Feeding stall system. Trickle feeding systems will look similar to Non-gated feeding stalls, except for the feed motors and feed delivery lines

Trickle feeding

Trickle feeding (Figure 4), sometimes called 'biofixation feeding', has similar penning and looks similar to Non-gated Feeding stalls. The major difference is in how feed is delivered. Special feed motors are used to deliver feed at a very slow rate so that the quantity of feed dropped is close to what a sow would eat in one bite. The idea is that if you 'dribble' the feed the sow stays 'fixed' in place as the feed drops from the feed tube. This usually takes 15 to 30 minutes.

Similar to non-gated feeding stalls, this is considered a small pen option and sows should be penned in static groups. Typically there is more equipment needed to install this option, compared to non-gated feeding stalls which make it more expensive.

July 2014

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