Optimal Flock Size for Pasture Raised Layers

Final report for FNC16-1028

Project Type: Farmer/Rancher
Funds awarded in 2016: $7,394.00
Projected End Date: 01/30/2018
Grant Recipient: Bluestem Farm
Region: North Central
State: Michigan
Project Coordinator:
Aaron Brower
Bluestem Farm
Expand All

Project Information

Description of operation:

Aaron Brower, along with his wife Mary, own and operate Bluestem Farm, a diversified, 4-season farm in Northern lower Michigan. They raise pastured proteins and certified organic vegetables on 80 acres of fields, woods and pastures. Bluestem Farm offers year-round csa shares, hosts community events and supports a food outreach initiative. They raise approximately 1000 layers, 60 pigs and 1500 broilers on pasture each year. They also grow about 10 acres of certified organic produce.


This project compares three sized pastured poultry flocks (100, 250, 450) in order to test what affect the size of the flock has on production and health. It will serve as an example to producers who are considering pasturing their layers and provide insights for raising safe and productive laying hens.

In the first year of the study, the birds went out to pasture when the fields were ready in April. We divided the flock into 3.  The two larger flocks were composed of 250 and 450 birds. For these respective flocks we utilized mobile  coops that we built in previous years. The 100 layer flock used a brand new coop we built in March of 2016.

For the first 2 ½ months they performed similarly. The 100 layer flock did lay a bit better but only by a small margin (less than 3%) and I didn’t want to draw any conclusions from this small difference.

This continued through May and into June, but by the first of July, our summer turned quite hot and dry. It was the hottest July and August we had experienced in N. Michigan and the layers' rate of lay suffered because of it. This was difficult for our farm’s finances but good for our SARE project. At this point, the larger flocks began to decrease significantly, dropping from >75% rate of lay to near 55%. Both of the larger flocks decreased significantly though the 250 layer flock performed slightly better (2-3%).

The 100 layer flock did not struggle nearly as much as the other two flocks in the unusual summer heat. Their rate of lay gradually dropped throughout the summer, but this is normal for us as the birds begin to age. By the summer, the 100 layer flock averaged about 72% which is the lower end of what we expect.

Between the growing seasons of 2016 and 2017, we contacted several farmers who raise pastured layers in hotter climates than ours in order to glean some tips on dealing with the heat. What was most clear is that in the heat, it is very important that the layer's drinking water not be too hot and that they have ample access to their feeders and waterers during this time. They primarily eat and drink during the cooler parts of the day and it is important that there is ample space for them to satiate themselves without competition or stress. 
Throughout 2017, we did not see any significant differences in production between the three sized flocks. There are several potential reasons for this. I believe it is the result of several flock management adjustments we made based on the discussions we had with southern farmers. We increased the amount of feeder and waterer space in the larger flocks. We made adjustments to ensure water did not get too hot. We added extra cover for shade and predator protection. It is also worth noting that 2017 was not an especially hot summer. We had plenty of days in the high 80's and in the 90's but no prolonged periods of extraordinary heat. 
Project Objectives:

There are two issues we wish to address with this proposal.

  1. We will test the efficiency of different size flocks raised on pasture.
  2. We will promote pastured poultry in Northern Michigan and provide a template that other small producers can follow.


Materials and methods:

There are a dizzying array of labels in the poultry world: ‘cage free’, ‘free range’, ‘non-gmo’, ‘corn and/or soy free’, ‘vegetarian’, 'organic'. Why should we consider adding 'pastured raised' to this list?

All the above labels are primarily defined by what they are not. 'Cage-free' and 'free-range' are not confined. 'Non-gmo' is without genetically modified feed. 

'Pasture-raised', on the contrary, is an affirmative label: animals raised on grass. Some people prefer to also include the factor of movement: animals moved from one grass paddock to another. For my purposes, I would prefer to keep it simple. If a chicken lives on grass, it is pastured raise.  There is no certifying agency for this. There is no official definition or group keeping tabs on farmers selling pastured raised animals. However, it is easy to recognize when you see it: Does the chicken have consistent access to grass?

We do this by keeping chickens in portable houses and surrounded by portable electric fences. Each of our 'chicken ships' is on a trailer that is moved with a tractor or truck. Each of these ships contains roosts, nest boxes, feeders and waterers. 

In the spring of 2016, our first year of a two year project, we built a movable coop and movable nest boxes for a 100 layer flock on pasture.

Unlike the larger pasture structures, we wanted the smaller flock structures to be moved by hand, so we constructed two separate units: A mobile unit for the roosts and a mobile unit for the nests. The water was kept with the nests.

In addition to the construction materials for these, we also purchased a feeder and components for a waterer for this 100 layer flock.  We also purchased 4 movable electric nets for security against land predators and we purchased a portable electric fencer and a deep cycle battery to keep the fence electrified.

Additionally, funds were used to help offset labor costs for the additional time needed to maintain an extra flock, to construct the pasture housing, as well as for the farm tour and talks.

In 2017, we made adjustments to the mobile unit for the roosts for the 100 layer flock. It was clear during the 2016 season that this unit was too heavy and adjustments were needed. It was difficult to move by hand. More durable and wider tires were put on it. The 2x4 roosts were replaced with 2x3's. These made the mobility slightly better, but it remained a challenge. It is clear that a more lightweight design is necessary if this unit is to be moved consistently without the help of a tractor or a truck.  For the purposes of our farm, after our adjustments, we've convinced ourselves that the most efficient way forward is to stick with the larger flocks of 250-400 birds and to move their pasture housing with mechanical help.

Typically on our farm we keep chickens of two different ages. We have some that are born in January and start to lay in June and we have birds born around May 1 and start to lay in October. We primarily cull the flock in the fall when they are coming off the pastures into their winter homes. We live in N. Michigan where we routinely get subzero temperatures and have winter averages of about 150+ inches of snow every year. For this reason, it is not possible to keep them on pasture all year. We also have a bigger market in the summer. We try to keep about 800-1000 layers in the summer and 600-800 in the winter.

We keep our birds laying from 50-75 weeks, depending on when they are born. In the winter, because we only have one large barn for the hens, we keep them all together and we separate them in the spring. If we had enough housing, we would maintain separate flocks in the winter as well, but this remains impractical for us for the time being.

Typically, we would keep the summer flocks separated by age, so that when they joined the flock, they would stay with their hatchling sisters, but for the purposes of this SARE grant, I mixed flocks so there was an equal representation of age groups within each flock. We track this with colored bands around the chickens’ ankles. This was important so that the age of the birds was not the determining rate of lay for each flock. Typically the birds’ peak rate of lay is between the age of 30 and 50 weeks. We often exceed 85% during this period. However, with the mixed ages, we do not average this. We hope to average 80% or above in summer, though we are satisfied with averages between 72%-75%.

Also of note, we typically buy in pullets (16-18 week old layers) around May 1st so that we have a strong proportion of our flock at peak lay during the summer months when we have the most demand for eggs. Presently we do not start these January chicks on our farm because we do not have the infrastructure to maintain their necessary temperature requirements during our harsh winters. We do, however, start day-olds on the farm in early May. These will be at point-of-lay (pol) in the fall and will replace the oldest hens as they are culled.

During the grassy time, we move our layers around the farm to ensure that they always have access to grass. We do not have a set time frame that determines when we move the layers. There are a number of factors, but on average we move each flock approximately twice a week. The key, for us, is that they always have access to grass. 

Each flock has a moveable shelter that is off the ground with a wire mesh floor that allows the manure to fall through onto the pasture but keep predators out. Each shelter is surrounded by portable electric netting that is kept hot by electric fencing. This does a good job at keeping land predators out, though we often struggle with aerial predators.

There are 2 independent waterers. Each has approximately 15' of trough space accessible from both sides. Each of these is kept full with a float valve and a water line gravity fed from a barrel. Each barrel is filled as necessary from waterlines running along the pasture fence lines. The goal is to maintain 2-3" of water trough space per bird, especially in times of extreme heat and cold. 

We provide several kinds of feeders. We have large range feeders and smaller hanging feeders along with DIY trough feeders made from 4" pvc. Similar to the water spacing, the goal is to maintain 2-3" of feeder space per bird. This allows for stress-free feeding and drinking. A stress-free chicken is a productive chicken. 

Research results and discussion:

The birds went out to pasture when the fields were ready in April. We divided the flock into 3.

The two larger flocks were composed of 250 and 450 birds. For these respective flocks we utilized mobile coops that we built in previous years. The 100 layer flock used a brand new coop we built in March of 2016.

With the larger flocks, the chicken ships (what we call the pasture housing) include roosts, nests and water and are moved around by a tractor or truck. However, with the smaller flock we wanted to be able to move them by hand so we made two different structures to keep the weight to a minimum. The roosts and the nests were separated and the water was housed with the mobile nests.

For the first 2 ½ months they performed similarly. The 100 layer flock did lay a bit better but only by a small margin (about 3%) and I didn’t want to draw any conclusions from this small difference.

This continued through May and into June, but by the first of July, our summer turned quite hot and dry. It was the hottest July and August we had experienced in N. Michigan and the layer’s efficiency suffered because of it. This was difficult for our farm’s finances but good for our SARE project. At this point, the larger flocks began to decrease significantly, dropping from >75% lay efficiency to near 55%. Both of the larger flocks decreased significantly though the 250 layer flock performed slightly better (3%).

The 100 layer flock did not struggle nearly as much as the other two flocks in the unusual summer heat. Their rate of lay gradually dropped throughout the summer, but this is normal for us as the birds begin to age. As is neared the summer's end, the 100 layer flock averaged about 72% which is what we expect by late summer.

The most troubling part of the decrease in lay rate was that the larger flocks did not rebound from the midsummer heat until deep into fall. Overall, it was a difficult year for the layers but the SARE project enabled us to draw some knowledge from our struggles.

Something we noticed was that the chickens in the smaller flock were eating a greater amount of their ration (per hen) than those in the larger flocks. It is known that one way that heat affects animals is that they do not eat as much and if a layer is not eating enough, they will not ingest enough of their nutritional needs and their rate of lay will suffer because of it. 

When we realized this, we bought additional feeders for the larger flocks. Through research we learned that the birds were all trying to eat in the cooler parts of the day, rather than through the whole day as they do in more mild temperatures. If this was the case, the feeders would be a bottle neck for them during these cooler times of the day to ingest enough feed or drink enough water to meet their laying needs.

An additional possibility for the rate of lay difference is that the larger flocks produced more heat as a whole in the night so that each individual bird did not cool down as much as the birds in the smaller flocks.


We adjusted the roosts on the inside of one of our shelters to make a ‘V’ shape with the roosts, rather than the standard ‘A’ frame. Our thinking is that the ‘V’ frame may allow more airflow at night and help with heat dispersement in the heart of summer. 

Year 2: The 2017 season

During the winter of 2016-17, we joined the American Pasture Poultry Producers Association (APPPA) list serve and connected with a community of like-minded producers eager to share their experience and knowledge. From some of the southern pasture poultry farmers, I learned some techniques used to deal with the hot weather. Above 85 degrees is hard on a layer. It causes stress. They only want to venture out toward their feeders or waterers in the cooler parts of the day. In the heat, they may only eat and drink enough to stay alive, but it takes much more than that to produce an egg with consistency. When this happens, it is imperative that there is plenty of room for most of the birds to eat and drink at once. This not only allows all of them to get their fill in the morning and in the evening, it creates less stress due to competition. This is not a clear issue during a typical day.  In such a situation, it may seem like there is plenty of space for all the birds, however, in the midst of a hot stretch of days, if one was to study a flock in the early morning when they just get off their roosts, one would realize that there was early morning competition for space around the feeders and waterers.

It became clear, that even though I may have had plenty of space according to waterer and feeder manufacturers, their information was based on ideal situations. It did not consider the special circumstances when birds are outside in the middle of the summer. 

Armed with this information, I bought additional feeders and manufactured additional trough and waterer space so that there was approximately 2-3" of waterer space per bird and 2-3" of feeder space per bird. I realized that the birds of the smaller flock always had more room at their waterers and feeders, thus allowing less competition and less stress in the early morning and late evening. It meant that the birds in the smaller flock never competed for drinks of fresh water or for their feed. 

Following these changes in 2017, I saw no noticeable difference in the rate of lay between any of the flocks. I averaged between 72-82% rate of lay, depending on the time of year. By early July, each flock was averaging between 78% and 82%. It remained near this level throughout August and tapered off through the rest of summer. As a reminder, these flocks are mixed with birds of varying ages. Some are at peak lay. Some are about a year old with their production beginning to wane. It is worth it to us to have some birds at a lower rate of lay during the summer. We have a much higher demand at this time of year and it works with our rotation. 

I also made a few additional adjustments to our flock management in 2017. As mentioned,I switched the set of roosts for one of the larger flocks from an 'A' shape to 'V' shape. My reasoning is that I believe this would create more airflow and the pasture house would retain less heat in the roosts at night. I intend to convert the remaining chicken ship to a 'V' shape for the summer of 2018. I also added apple cider vinegar to their water during periods of heat. This adjusts the ph of the water and is said to reduce stress. 

Further, I provided additional shade structures to both of the larger flocks. I found some lightweight, used trailers and built a simple flat frame on their top. A large tarp was stretched over this frame. This not only worked to provide additional shade, it also gave the birds additional cover when there were aerial predation issues. 

None of the above gets at the initial question: What is the optimal layer flock size? Is smaller better? My conclusion for the moment is that size does not matter. What matters is that every bird have ample space to eat and drink to reduce stress. There needs to be plenty of shade for every bird and protection from predation to the greatest extent possible. 

One may respond to this: why don't you just put them in a barn at 70 degrees and give them everything they need for optimal performance? Our answer is that we place a great deal of value on raising chickens on pasture. We want them to have a life out of doors with constant access to grass and sunshine as much of the year that our climate allows. Because of this, we open our birds up to a higher degree of predation and stress from the elements. It is our duty as stewards to minimize the dangers and stresses of predation and climate to the greatest degree possible within our systems. 

Our systems are constantly evolving. Going forward, we will limit our flock size to about 350 layers. Not because that is an ideal number for all pastured layer producers, but because, for our moveable houses, it is the size that fits. 

Participation Summary
1 Farmers participating in research

Educational & Outreach Activities

10 Consultations
2 Curricula, factsheets or educational tools
8 Tours
3 Webinars / talks / presentations
1 Workshop field days

Participation Summary:

250 Farmers participated
10 Ag professionals participated
Education/outreach description:

Bluestem gives farm tours through the summer. We gave 4 in 2016 and 4 in 2017. On average we have 25-40 people attend each of these events. The attendees are primarily our customers and the local food consuming public, but there are usually a few local farmers and interns from nearby farms.

In late summer of 2016 we held a field day on the farm. The sole focus was on raising layers on pasture. It was publicized in conjunction with Crosshatch, a non-profit organization that focuses on ecology and farming. It was part of a twilight-farm tour series.

The tour lasted about 2 hours and was attended by about 65 people.

In January 2017, Aaron presented at the Northern Michigan Small Farm conference. It annually has about 1000 attendees. Aaron’s session was entitled “The 100-Layer Flock on Pasture”. There were approximately 100-125 people in this session. The attendees are primarily farmers and aspiring farmers. 

In January 2018, Aaron presented at MOFFA's annual organic intensive conference. Aaron gave two presentations, including a talk on pastured layers. This was part of an intensive workshop entitled "Small to Medium Scale Livestock for the Integrated Farm". This conference was intended for farmers and aspiring farmers with approximately 150 attendees. About 1/3 of these attended the livestock portion of the conference.

In March of 2018, Aaron will make a presentation on pastured layers at the Indiana Small Farm Conference as part of the NCR-SARE Farmer Forum.

Approximately 10 people contacted Aaron for more information and for consultation on raising layers on pasture. Most of these were either nearby farmers who attended an event at the farm or reached out to Aaron after attending one of the conferences at which Aaron made a presentation.

Attached is the presentation Aaron most recently used at the MOFFA Organic Intensive, which provides a broad overview of many aspects of pastured layers along with lots of photos.


Attached below is an example budget for pastured layers, providing examples for 100, 250, 500, and 1000 layer operations.


Learning Outcomes

6 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Lessons Learned:

In the heat of the 2014 summer, we experienced a serious decline in the production for our flock. We didn't understand what caused the issue. We received some advice from a fellow producer who recommended we split the flock and with this adjustment, the rate of lay began to increase. From this limited experiment, we began to plan for this trial. 

The first year of this trial, 2016, was also quite hot and we also experienced a decline in the production of 2 of the 3 flocks of this experiment. It seemed after that first year that flock size did have a strong influence on rate of lay, but I didn't understand why. I wanted to understand the reasons. I wanted to know if there was an adjustment that I could make in the larger flocks.

That winter I began seeking out the advice from southern producers who deal with heat all the time. The consistent advice that came back was to provide more feeder and waterer space, especially during the peak times of climate stress.

It was explained to me that layers will not eat much in the heat of the day. Because of this, it is imperative that the birds have ample trough space in the heat so more of them can eat freely during the cooler parts of the day. This helps to ensure that they consume enough of a well-balanced ration to lay proficiently. 

Water can become even more of an issue. An egg is said to be 75% water. If a chicken only drinks enough to get by, it will not be able to produce an egg. It is vital that clean water be available at all times and that there is ample space so that most of the birds can drink at once. Also, it is important that the water is not too warm. If the water is unpalatably warm, the birds will not consume it. For this reason, we buried waterlines where this was practical and moved other waterlines into the high grasses for shade. Additionally, on the warmest days, we purged the warmer water from the lines into the pig wallows, thus giving them extra water for their needs and providing cooler water for the chickens' waterers. 

Additionally, we learned that chickens eat for energy not for protein. Energy is heat. Because of this, they eat less in the summer. This means that in the extreme heat, layers often do not consume enough protein. If they do not eat enough protein, they will either produce small eggs or stop producing entirely. For this reason, it can be beneficial to increase the protein and/or decrease the energy in the summer ration for layers. The exact opposite could be beneficial in the winter if the layers are exposed to too many days below freezing. In those circumstances, it would be beneficial to increase the energy and decrease the protein. 

After our first year of this grant, I believed I would need to create a fleet of smaller moveable shelters to maintain a higher rate of lay. The problem with this, I feared, is that it would decrease the  efficiency of the farm and also require a higher cost for infrastructure. However, with the adjustments we've made, we will continue to pasture our layers in flocks of 250-350. We will continue to do research and make adjustments. We will pay extra close attention to the layers performance in the summer heat. 

Project Outcomes


We continuously make efforts to reduce predation, but it remains a consistent problem. It was told to me that red sex links are not especially skilled at avoiding bird predation. I think it would be a worthwhile study to have several flocks with a variety of breeds to track predation rates and also their rates of lay in times of predation stress. Whenever we have an issue, the rate-of-lay dips in our flocks. 

If other breeds are better at avoiding predators they may be more economically viable options for the small farmer. Typically, pasture poultry producers use sex links (primarily red sex links) because they have an excellent rate of lay, they efficiently convert feed, they have a pleasant disposition and they are a good forager. However, they have a relatively short production life (about a year) at a high rate of lay.

Potentially it could make economical sense to keep a breed that was better at evading predators and dealing with the stress of the outdoor life. They may have a slightly lower rate-of-lay than sex links, but they may potentially have a longer active productive life, thus foregoing the need to raise new pullets every year.

I believe this would be a useful economic study for a pasture producer to explore.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.