The Dawn of Proposition 12 – More Questions than Answers!

Jun 7, 2022

I have designed group housing systems and worked with pork producers in the US for more than 20 years. If our industry is ever going to be satisfied with the outcomes from group housing of sows, then, in my opinion, we must continue to seek a better understanding of the challenges that lie ahead.

Millions of dollars have been spent on remodeling existing barns, along with a few new barns, in a noble attempt to meet the January 2022 deadline, even with regulations that have been both vague and a moving target! Today, around 500,000 sow spaces are reported to be in various stages of completion.

In the last 18 to 24 months I have been asked numerous times, “How would you go about designing a barn for Prop 12?” I believe there are 4 key elements that should not be overlooked when making the decision.

The 4P’s to consider with any Group Housing AND Prop 12 designed barn.

  • People

  • Pigs

  • Production

  • Pocketbook

We know that labor has become an Achilles Heel for most every business. The phrase that, “People are your biggest asset!” has never rung truer. It is easy to sit in an office, work with builders, and invite in industry experts as you design a barn. But NEVER FORGET, it’s the people whose feet touch the ground inside that barn every day who will ultimately play one of the biggest roles in the success of the farm. We therefore need to make a balanced decision that covers those 4P’s.

What Prop 12 Group Housing Options  are there?

Most of the Prop 12 layouts for gestation sows that I have been involved with have been considering one of the following combinations of sow housing systems

1. Free Access Stalls (FAS) to 6 weeks of pregnancy, then moved to ESF pens for 10 weeks (6/10)

2. Free Access Stalls (Breeding only) moved to ESF Stage 1 Pens, for  between 4 to 6 weeks (with heat detection), then moved a second time to ESF Stage 2 Pens for 10+ weeks

3. Free Access Stalls (Breeding only) – then moved to Stanchion or Shoulder Stall Pens for 16 weeks

As with most things, there are pros and cons. You can argue a case for each, or any other group housing options I didn’t mention. My list is by no means all-inclusive! In most debates you will get drawn to one side or the other in order to convince yourself that your decision is right. Based on everything I have seen over my time in the US, and working closely with ESF, I believe a balance must be achieved of both simplicity and technology.

I wrote an article in May 2019 called ‘Simplicity is the ultimate sophistication in Group Sow Housing’ –

‘When a group housing system is too simple there is a compromise for the sow but when it becomes too complex then the compromise is with the people. In most cases production is affected either way! I don’t believe that “too simple or too complex” is likely the sustainable answer for group housing in the US! There is a lot to think about and the decision should be carefully evaluated on a case-by-case basis.’

What questions do I need to ask myself?

Deciding on a barn design to comply with Prop 12 is not easy. If we can agree that we use a Free Access Stall system from weaning until post-insemination, then here are a few questions you should answer.

• What’s my budget?

All FAS or all stanchion pens, from this point, will be more expensive than all ESF stations in your gestation pens. Costs will vary; however, once you combine the expense of both the FAS and additional penning that is often associated, I have seen numbers that are significantly higher.
Some additional feed costs are also asssociated in semi-competitive feeding systems such as FAS and Stanchions.


• What can my people manage?

I would strongly advocate doing some ‘production due diligence’, before deciding to try Proposition 12.
Remember that all Prop 12 designs require a group-housed setting for the animals. It means pigs are together at the implantation stage between day 7-14 following insemination. A critical time in a stall, let alone a pen!


• When was the last time you inseminated pigs, mixed them almost immediately, and monitored the results?

It may have been 20 years ago with different genetics, and you did it by yourself. Or maybe never!
Typical farms have a GDU, and that’s a good place to see what your pigs and people can achieve by doing a grouphoused, gilt breeding project. Can they maintain 90+% conception over a 3-to-4-month period, or does it drop to 80%?

New barn or remodel?

On remodels, issues such as slat orientation, areas of solid concrete and positioning of alleyways all should be considered in the design. Dig deep in your thinking ask yourself the question – “What can my labor force manage, both today and in the years to come – am I setting my people up to be successful?”

• Do I have employee buy-in ?

It’s key! Your people must believe that the production results you require are achievable. If they have never done pre-implantation gestation with animals in groups and don’t understand the animal behaviors and physiology
associated – who’s to blame?

If you are still unsure about these answers then a balance of technology and simplicity maybe the best approach, based on what I have seen in ESF barns in the U.S., over the last 20 years. Remember, it’s my opinion from what I call, “the experience behind the eyes!” Training a person to become a good stockperson is a challenge. As I mentioned, we must now help them understand both animal behavior and the physiology. For example, giving a person a clear understanding of why it is not a good idea to add a couple of sows to a pen just because you took a couple of return sows out just to, ‘make up the numbers in the pen!’

How does 6/10 Group Housing work for Prop 12?

I believe that individual feeding of sows and gilts is beneficial at any point in their reproductive cycle. The data over decades is not questioned. Using either FAS or ESF post-insemination checks that box. However, a 6/10 system requires animals to be housed (and fed) in FAS pens from weaning to around 42 days, which goes against most nutritional recommendations.

The compromise with this 6/10 scenario is that animals ideally need to be grouped at weaning into body condition type, as feed levels will all have to be set the same in each pen as we don’t know which animal will choose which FAS! Feed could occasionally be wasted and some sows get either slightly under or over what we would ideally like them to receive.

Through this period, from weaning to around 6 weeks of pregnancy, we know that animals still have some protection during the time they eat if you adopt a % of FAS in your system. If necessary, additional feed could be given to individual animals. ‘That takes labor!’, I hear you say. True, however it may create better individual observation and animal care, which is often lacking in many preimplantation ESF systems.

An advantage of the 6/10 is that when animals are moved to ESF pens (42 days) it provides an opportunity for easier body condition scoring, with animals lined up in FAS, enabling a routine identical to an all-stalled barn. After moving, the ESF can then take over and you can individually tweak body condition on any animal that may need nutritional adjustments. The 6/10 system gives a balance of both simplicity and technology for the people.

The mixing of animals at weaning is one of the least understood challenges of Prop 12 designed barns. Some 25 years ago, I got to mix animals in groups at weaning, outside on the pasture-based farms. I would watch helpless, as sows would fight and tear down my electric fencing. Other ‘boss sows’ would take delight in chasing their timid pen mates, for what seemed like miles, hoping for a little unarmed combat! The 6/10 does provide some refuge in the FAS compared to ESF, in all the post insemination pens – if only for a short period of time!

A few more things to consider!

Remember that during this first 6-week stage, if using just ESF as a feeding strategy, be aware that the following tasks will require suitably trained people with the ability to follow what I call ‘ESF 101 Routines’ –

• Making sure all animals are eating at what is a critical time for conception and subsequent litter performance (the bottom 10% of timid animals are the most vulnerable).

• You will have a ‘no-eat list’ at this important stage that will need dedicated labor daily. This list of non-eaters will typically be less when ESF pens are formed at 42 days. At this time pregnancy is confirmed, therefore if a sow misses a meal for some reason the effects on production are significantly reduced.

• Tracking 3 week returns, where using additional technology (e.g. automated heat detection) requires disciplined, well-rehearsed routines and computer savvy labor!

• Pregnancy checking in an ESF pen v in Free Access Stall pen – both are achievable, but the latter has more control and typically takes less time. Open sows are subsequently easier to remove as they are shut in the FAS for pregnancy check (make sure to follow the Prop 12 ‘rules’ for shutting sows in!)

• Finding and treating animals daily can take more time in ESF pens. The first 10-15 days post-weaning is when the most fall-out from injury will generally occur as hierarchy for the feeders is established. FAS is more like the stalled system and may be easier for your people, giving a built-in temporary hospital – with food and water readily available!

Observation of animals in FAS has so far suggested that a significant amount of time is spent just ‘hanging out’ in the stall. Compared to stanchions, animals’ reproductive organs are better protected in FAS both at feeding and when they are resting. The FAS will often become the animal’s sanctuary from weaning to 6 weeks. She will feel safer, and it provides easy observation for the barn staff.


In my mind it is imperative to take a close look at the 4 key elements before designing a Prop 12 barn. There is no ‘one-size-fits-all’ answer. Even though I believe that ESF works at all stages of gestation, there will be cases  when adding more Free Access Stalls and fewer ESF stations is a better choice. I am saying this with your people, the pigs, production results and your pocketbook all in mind. Remember those 4P’s while you look for a balance of simplicity and technology that fits your farm.





The stall allowed for non-competitive individual feeding. We can still do that with group housing and with Prop 12 designed barns in such a way that we can cater to both the producer and the employee, as well as the animals. We need to reduce animal movements, reduce fighting with minimal mixing, and ultimately reduce stress for both the people and pigs! If we continue to ignore all technology, we will go backwards as an industry. Both Poultry and Dairy are showing us the way. Think of the future.
What will it look like 10 years from now? Will we have the answers to the questions that will undoubtably continue to be asked of us? We must take what mwe know and apply it to the designs of these Prop 12 barns. I truly believe that, as they say, “The ship has left the dock”, and once you make your choice on your feeding system for Prop 12, it will be both costly and difficult to re-do it.

No group housing system is perfect. No matter how acceptable the system may be in principle, without diligent, competent stockmanship the welfare of any livestock is in jeopardy! Group housing is so much more than choosing the way you feed the sow. It’s not just about buying feeding equipment; it’s about finding solutions for all areas of the operation to see our Industry into the next decade and beyond.


You are invited to stop by the Maximus Booth V105 at the 2022 WPX, Des Moines Iowa – June 8th-10th to talk to Robert Drew and Joel Phelps to see how we can help you with your Proposition 12 barn design

About the author

Robert Drew

Robert Drew has well over 3 decades of experience that he brings with him to MAXIMUM AG in both Outdoor and Indoor sow producti on on a large scale.
Along with establishing on-farm Quality Management Programs and Independent Consulti ng roles, Drew’s knowledge on group housing is a great additi on for MAXIMUM AG and its customers. His fi rst exposure to ESF technology was more than 30 years ago in the UK.
More recently he has worked with many of the other group feeding systems in the US as the industry started to adapt to the European way of thinking.

I believe that MAXIMUS can provide a foundation for true animal care through precision monitoring of all the critical areas of the production system.