Evaluate the Efficiency of Raising Pastured Egg Layers in a Compost Heated Hoophouse Over Winter and Their Influence on Compost Quality

Final report for FNC22-1325

Project Type: Farmer/Rancher
Funds awarded in 2022: $9,716.00
Projected End Date: 01/15/2024
Grant Recipient: Sleepy Bison Acres
Region: North Central
State: Minnesota
Project Coordinator:
Craig Fischer
Sleepy Bison Acres
Expand All

Project Information

Description of operation:

Sleepy Bison Acres is a family owned operation that raises bison, pork, and eggs with a pasture based rotational system. We also grow a small amount of row crops. The pasture system changes depending on the supply and demand of the herds, which usually follows the seasons of the year. Depending on the time of the year, we may utilize strip grazing, high stock density grazing, rotational grazing, or resting pastures completely. The farm began in 2013, and operates primarily on 100 acres.
Before receiving this grant we were MN Water Quality Certified.


Too often chicken houses are too dark, cold, and smelly during the winter season creating conditions that make egg production expensive and less than optimal for the farmer and hens. 

By utilizing a modern hoopbarn to optimize sunlight, protect the flock from extreme cold weather, and utilize waste heat from compost generated from our bison bedding pack, we can evaluate the profitability of a limited energy inputs egg laying flock. Simultaneously, while reducing potential nutrient runoff into the water cycle. CO2 and NH3 levels will be the key air quality gases monitored. Carbonaceous bedding will be routinely added to ensure air quality for the farm workers and hens as well as proper C:N ratio for compost. The compost will be tested before fall season hoop house piling and before spreading on family farm fields in the spring for nutrient quality.

Quality of life for the farmer will improve in part to the limited inputs and reduced time spent to clean dirtied eggs, increase in saleable unfrozen eggs, and quality of life for chicken flock. The hens will be removed from farm fields in the muddy seasons of spring and fall, potentially avoiding soil health damage during dormant seasons. 

Project Objectives:

Evaluate the Efficiency of Raising Pastured Egg Layers in a Compost Heated Hoopbarn Over Winter and Their Influence on Compost Quality through:

  1. Evaluating compost heat as an energy source to maintain a chicken flock profitably through winter.
  2. Evaluating Compost Nutrient Quality before and after hoop house utilization as a salable product for the farm.
  3. Decrease risk of nutrients leaching by stabilizing nutrients through compostable bedding



Materials and methods:

A hoop barn with a tarp roof as clear as possible was chosen in order to allow beneficial light for the poultry, while simultaneously collecting and retaining heat from the sun. The building was built from galvanized metal, wood, and tarps, which is believed to minimize the long term building depreciation as building materials are not as susceptible to corrosion.

The hoop building was constructed in the late fall by hired contractors and sealed with wooden boards. The floor was leveled before the addition of used  hog slats for a stable floor structure that was easy to clean. Due to the timing of the project construction, the majority of the usable bison compost was frozen by the time the building was ready. As a substitute for compost heat, a layer of wood chips, corn stalks, and old hay were gradually applied. Due to the cold temperatures drafting through the cracks in the boards and end walls, the compost pile never achieved proper heating over the winter.  

Silicone and spray foam insulation were applied to help weather seal the structure, mostly to the sidewall boards, and end wall corners that were difficult to seal. Silicone application proved to be a constant battle, as the silicone sealant did not stay in place when the snow melted off the top of the tarp, ran down, and caused moisture to accumulate and sweat in between the side boards of the hoop barn. Several reapplications were applied, on the inside and outside of the building as weather allowed.

Replacement laying hens were added in the early spring of the year. 

Our pig enterprise was added in late spring to turn the compost. The pigs were brought in hopes of creating more sources of heat, the need to find a new home due to piglet supplier demands, and loss of previous pig grower housing.

Temperatures were observed at dawn and in evenings when eggs were picked.

Summer heat and drought caused the cracks between the sidewall boards to expand, causing increased airflow all around the building. Increased airflow proved to be a benefit over the summer heat, as the end doors needed to be open to maintain comfort for the chickens, but was a foreseeable issue going into the cold season.

To counter additional cold drafts, self adhering ice and water roofing underlayment was applied prior to winter, in addition to steel siding to protect from the outdoor moisture and wind.

Year 2 winter conditions were abnormally favorable, which allowed for extended grazing for the chickens and optimal airflow through the hoop barn for the birds. The abnormally warm temperatures and inside temperature of the hoop structure allowed us to refrain from using electricity to run the heat box warmers, as the temperatures were high enough to prevent the eggs from freezing before they were picked.

With the warmer temperatures, of year 2, a generous amount of compost was collected and piled. As temperatures decreased, an increasing amount of chicken litter was added to the pile, eventually leading to a lower than desired C:N ratio.

Compost was turned 1-2 times per week. Compost was turned in the dark, as moving equipment operating inside the same building as the chickens tended to be dangerous for the birds. Turning and adding compost tended to be less dangerous for the birds, but was still an issue as headlights were frequently required, and tended to be enough of a light source for chickens to explore the turning process looking for food.


Research results and discussion:

Compared to the cold temperatures outdoors, the temperature inside the hoop barn tended to be 7-11 degrees warmer than outdoors over the first winter season, depending on the sun and wind. Overcast and windy days were prevalent over the first winter, which meant temperatures were less favorable inside and outside.

Increased flock numbers did little for observable temperatures, as body heat is generally contained within a chickens feathered body. 

The addition of the pigs added around 2 degrees to the building. Even though the pigs leveled the compost pile, the increased temperature was likely attributable to the increased body heat, activity, and constant turning of the bedding materials.

As the sun angle increased, so did the observed indoor temperatures, increasing to a pleasant 10-16 degrees warmer than outdoor temperatures.

The addition of the roofing underlayment, steel siding, and further weather proofing inside the building, led to temperatures that typically ranged from 13-22 degrees warmer than outside. Dependent on overcast or sunny conditions.

The pile was large enough that the ammonia levels became an issue. Due to the loss of our wood chip source, which had high C:N and slowed decomposition due to particle size, waste hay became our primary Carbon source. The addition of the hay did not remediate the increased ammonia and methane production as expected, as C:N was typically 7:1-12:1.

The chickens tended to avoid the compost pile, unless enticed by food. Even when enticed by food, the chickens generally grabbed their food and ate away from the compost pile, unless the pile was being turned in the daylight. The presence of concentrated ammonia from the compost seemed to be the main culprit for this behavior.

Conventional barns have plenty of aeration with barn fans and consistent heat for the birds, which help combat ammonia buildup.

In this case, the lack of barn fan ventilation meant the hoop barn end doors needed to be opened to let the chickens range before sunset and let the building aerate before any additional work is done. Since the building does not have running water, this proved a good way to avoid hauling water or stringing garden hoses to fill the chickens waterer every 2-3 days, as the chickens readily ate snow or drank out of the livestock waterer. In a mild winter situation, this is a more realistic option than an abnormally cold or snowy winter, like year 1, as indoor temperatures would decrease whenever doors open due to the increased exposure to outdoor temperatures and conditions.

Worth noting, chickens are perfectly content consuming snow instead of liquid water, at a price of decreased egg production due to the increased calorie energy needed to convert the snow to water.

Due to the increased presence of less than desired air quality, considering deep bedding with high C:N ratio products, such as chopped straw, sawdust, or wood chips in addition to the "clear" colored tarp roof, and weather resistant sidewalls, may be more beneficial for the farm manager and chickens housed inside the building, than an intense compost heated system.  Equipment operation that is not restricted to night use will also decrease the safety risk for the operator, any helpers, as well as equipment or possible building damage. Not to mention the increased safety for the birds, if there is equipment operating less frequently in their presence.

Participation Summary
1 Farmers participating in research

Educational & Outreach Activities

1 Consultations
1 Published press articles, newsletters
2 Tours
3 Workshop field days

Participation Summary:

52 Farmers participated
1 Ag professionals participated
Education/outreach description:

Provided an on farm field day for the South Central MN college Alternative Ag class in the spring of 2023. Approximately 10 individuals attended the farm day with their instructor.

In July of 2023, the National Bison Association hosted a regional regenerative field day on the farm. Approximately 31 farmers attended. This field day was circulated through the NBA website, weekly updates, and magazine.

As a regular contributor to the Minnesota Bison Association newsletter, this allows me to regularly speak with other producers about the challenges and successes of projects like this. Farmers are generally interested in the application of farm concepts they previously didn't understand or could help their own operations.

In September of 2023, Sleepy Bison Acres hosted a regenerative field day on the farm. Approximately 80 people attended, 21 of those were farmers. This event was highly publicized by the farm through farmers markets, deliveries, monthly farm updates, and social media. Farm customers are continually updated about the farm and farm happenings.

Learning Outcomes

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

It is better to build a hoop barn in warmer weather. Ours was finished right before the weather turned cold, so the tarps did not have time to settle into the proper place. After settling into place, we were advised to strap the ratchets tighter when the weather warmed up. Due to the unpredictable weather timing of Minnesota, we endured high winds, snow events, and a 3 day blizzard, and a cod snap immediately after beginning year 1 of the project. This increased the snow load on the building, due to the nature of the storms, as well as the fact that the tarps were not retightened with warm weather. This meant there were places for the snow to collect, and add stress to the structure. Without the aid of warm weather in year 1, we were obligated to help the structure in shedding snow.

Our hoop barn was purchased with a "clear" cover. When free of snow cover, the clear cover lets a noticeable amount of sunlight inside.

With the increased sunlight, warmth, and ease of sanitation, our egg production doubled in year 1, compared to our previous farm building. In year 2, our egg production has taken a substantial leap again, likely due to the influx of younger chickens that are continually producing, and the decrease of age flock members.

If your hoop barn is not sealed tight, it is hard to get or keep the building warm. The cold soil beneath the structure did not help build sustainable warmth in year 1 as the building had to not only warm itself, but the soil below it.

A concrete floor and concrete sidewalls would help seal the building better than wood, but come with a higher cost. To counter the higher costs of a poured concrete floor and sidewalls, used hog slats provide a solid floor that is easily cleaned and maneuvered by machinery.

Utilizing wood for the hoop barns sidewalls is acceptable. It may be best to seal the side walls with some kind of steel, tar paper, wrap, or sealant, or a combination of sealants. This allows for increased comfort in the winter months, but will require increased circulation in the summer months.

A taller building gives the advantage of more flexibility in storing necessary equipment, maintenance equipment, or compost buildup.

Proper ventilation is a must. The amount of gasses produced by more active compost was underestimated. That, coupled with the inability to access higher C:N ratio bedding and abnormally higher temperatures in year 2 caused higher than expected gas production from the compost.

The disadvantages of our building have focused on weather and ventilation. Concrete floors and end walls would help fix weather drafts, but requires extra labor and a higher financial investment.

Taller buildings are a positive for storage, but are more difficult to build and maintain heat from the ground level.

Heat on the inside of a building will help the building shed snow faster. Another consideration to keeping the building warm is the type of animals that are kept inside and how much heat they generate. Other livestock producers that have kept cattle inside report the cattle generate more heat and keep the building warmer than pigs or chickens. Different livestock types need to remain mutually beneficial and need to be able to coexist peacefully. 

Without consistent heat on the inside of the building, plumbed water becomes more of a risk. Hauling water or garden hoses are a cheap remedy if close to a water source, but add more labor.

We have found farmers generally learn better by speaking to other farmers about their experiences. If other farmer or ranchers would like to learn more, we would encourage them to reach out to us directly to speak over the phone or a tour in person to discuss our experiences. 

Project Outcomes

2 Farmers changed or adopted a practice
1 New working collaboration

Would like to see benefits of 12-24" deep bedding system and its effect on livestock health and production.

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.