Sheep Barn Odor Control: Ventilation, Bedding, and Manure Management

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Elevated ammonia levels (above 25 ppm) in sheep barns significantly irritate the respiratory tract and eyes, increasing susceptibility to pneumonia and reducing feed intake; monitoring via ammonia test tubes or electronic sensors is crucial.
• Moisture is the primary driver of odor, facilitating bacterial decomposition of manure and urine; maintaining relative humidity below 80% through adequate ventilation and dry bedding is paramount.
• Effective ventilation, both natural (ridge vents and sidewall inlets) and mechanical (fans), is essential for removing ammonia, moisture, and dust, with minimum winter rates of 20-30 cfm/ewe and higher rates for warmer weather.
• Deep bedding systems, when managed with an appropriate carbon-to-nitrogen ratio and regular turning, can create a composting effect that minimizes odor and maintains a dry surface for sheep.
• Bedding material choice impacts moisture absorption and longevity, with wood shavings generally offering superior absorbency and odor control compared to straw, though cost and availability are factors.
• Overstocking, blocked ridge vents, use of wet bedding, and ignoring water leaks are common management errors that exacerbate odor problems and negatively impact flock health.

Strong odors in a sheep barn are more than an inconvenience. They signal that ammonia, moisture, or airborne dust is building up in the air your flock breathes. Poor air quality irritates the respiratory tract, stresses the animals, and can lead to pneumonia, poor weight gain, and reduced wool quality. This guide explains why sheep barns smell, how to measure and fix the problem, and how to keep air quality in a healthy range. It is written for sheep farmers, barn managers, and anyone responsible for the daily care of housed sheep.

At a Glance

The rest of this guide walks through each of these points in detail.

Why Sheep Barns Develop Strong Odors

Odor in a sheep barn comes from the natural breakdown of manure, urine, and bedding. When sheep urinate and defecate indoors, bacteria begin to decompose the organic matter. This process releases gases, including ammonia, hydrogen sulfide, and methane. The most common and most irritating of these is ammonia.

Ammonia forms when urea in urine breaks down. The enzyme urease, produced by bacteria in feces and on barn surfaces, speeds up this reaction. Warm temperatures and high humidity accelerate the process. In a poorly ventilated barn, ammonia gas accumulates in the air. At low levels it produces a sharp, pungent smell. At higher levels it burns the eyes and respiratory tract of both sheep and humans.

Moisture is the main driver of odor problems. Wet bedding and damp manure create ideal conditions for bacterial growth. When bedding stays wet, the bacterial population explodes and gas production increases. A dry barn with good air exchange produces far less odor than a wet barn with stagnant air.

The type of bedding also matters. Straw, wood shavings, sawdust, and recycled paper all absorb moisture differently. Straw is cheap and available in many areas but breaks down quickly. Wood shavings absorb more moisture and last longer. Sawdust is highly absorbent but can be dusty. The right choice depends on your climate, your budget, and how often you clean pens.

The Health Impact of Poor Barn Air

Ammonia is not just a smell problem. It is a respiratory irritant. Sheep exposed to high ammonia levels develop inflammation in the nasal passages and lungs. Over time this makes them more susceptible to bacterial pneumonia and other respiratory infections. The effects are worse in lambs, whose immune systems are still developing.

Studies have shown that ammonia levels above 25 parts per million (ppm) cause measurable irritation to livestock. At 50 ppm, sheep may show signs of eye irritation, coughing, and reduced feed intake. Levels above 100 ppm are dangerous and require immediate action. Your nose is a useful tool, but it is not precise. If you can smell ammonia when you walk into the barn, the level is likely above 10 ppm. If the smell makes your eyes water, the level is probably above 25 ppm.

Carbon dioxide is another concern. Sheep exhale carbon dioxide, and in a tightly sealed winter barn it can build up. High carbon dioxide levels make sheep lethargic and reduce feed intake. Oxygen levels can drop in extreme cases. Good ventilation removes carbon dioxide and brings in fresh oxygen.

Dust and airborne particles also affect air quality. Feed dust, dried manure particles, and dander from the sheep themselves can irritate the respiratory tract. These particles can carry bacteria and viruses. During handling and feeding times, dust levels spike. Good ventilation helps clear these particles from the air.

Measuring Barn Air Quality

You cannot manage what you do not measure. Several tools are available for monitoring sheep barn air quality.

Ammonia test tubes are the simplest option. These glass tubes contain a chemical that changes color when exposed to ammonia. You break the ends off a tube, attach it to a hand pump, and draw a measured volume of air through it. The color change indicates the ammonia concentration. These tubes are inexpensive and accurate enough for routine monitoring. They are available from farm supply stores and online retailers.

Electronic ammonia sensors provide continuous monitoring. These devices use an electrochemical sensor to measure ammonia in the air. They are more expensive than test tubes but give you real time data. Some models connect to your phone or computer and send alerts when levels get too high. These are worth the investment for larger barns or barns with a history of respiratory problems.

Carbon dioxide monitors are also useful. Handheld units measure carbon dioxide levels in the barn. Levels above 3000 ppm indicate poor ventilation. Levels above 5000 ppm are dangerous. Many carbon dioxide monitors also show temperature and relative humidity.

Relative humidity is a key indicator of air quality. A barn with relative humidity above 80 percent has too much moisture. This creates conditions for ammonia production and bacterial growth. A simple hygrometer costs less than 20 dollars and should be standard equipment in every sheep barn.

Your senses are also valuable. Walk through the barn at sheep level. If your eyes sting or your throat feels scratchy, the air is unhealthy. Pay attention to how the sheep are behaving. Coughing, nasal discharge, and watery eyes are warning signs.

Ventilation: The Foundation of Odor Control

Ventilation does two jobs. It removes stale air, moisture, ammonia, and dust from the barn. It also brings in fresh air from outside. Both jobs are essential for odor control.

Natural Ventilation

Most sheep barns rely on natural ventilation. This uses the wind and the difference in temperature between inside and outside air to move air through the building. Natural ventilation works well when the barn is designed correctly and the openings are managed properly.

The key to natural ventilation is having both inlet and outlet openings. Inlets are openings at the lower part of the barn, usually in the sidewalls. Outlets are openings at the ridge or peak of the roof. Fresh air enters through the inlets, warms up inside the barn, and rises. The warm, moist, odorous air exits through the ridge. This is called the stack effect.

For this to work, the ridge opening must be continuous along the length of the barn. A ridge vent that is blocked, covered, or too small will not allow enough air to escape. The sidewall inlets must also be adjustable. In winter you want to open them just enough to provide fresh air without creating drafts on the sheep. In summer you want them wide open.

The total inlet area should be roughly equal to the ridge outlet area. If the ridge is 12 inches wide, the combined sidewall openings should be about 12 inches wide along the length of the barn. This balance keeps air moving at the right speed.

Mechanical Ventilation

Mechanical ventilation uses fans to move air. It is necessary in barns that are tightly sealed, in cold climates where windows and doors stay closed for long periods, and in barns with high stocking density.

The most common system for sheep barns is negative pressure ventilation. Fans on one wall pull air out of the barn. This creates a slight vacuum that draws fresh air in through inlets on the opposite wall. The key is to have the inlets sized and positioned correctly. If the inlets are too small, the fans create strong drafts near the openings. If the inlets are too large, air movement is sluggish and dead zones form.

A minimum ventilation rate for sheep is about 20 to 30 cubic feet per minute (cfm) per ewe during cold weather. This removes moisture and ammonia while conserving heat. In mild weather, the rate should increase to 50 to 100 cfm per ewe. In hot weather, rates of 200 cfm or more per ewe may be needed.

Variable speed fans are worth the investment. They can run at low speed in winter and higher speed in summer. Thermostats and timers can automate the system. A simple controller that turns fans on when the temperature rises is better than no controller at all.

Seasonal Ventilation Adjustments

Ventilation needs change with the seasons. In summer, the goal is to remove excess heat and keep air moving over the sheep. Open all doors and vents. If the barn has a ridge vent, make sure it is fully open. In hot climates, consider adding circulation fans to keep air moving across the animals.

In winter, the goal is to remove moisture and ammonia while preserving heat. This is the hardest balance to strike. The barn should be warm enough to keep sheep comfortable but ventilated enough to keep air dry and fresh. A good rule of thumb is that the air inside the barn should not be noticeably humid or smelly when you walk in.

In spring and fall, ventilation is easier. Moderate temperatures allow you to open the barn up more. Use these seasons to air out the building thoroughly and dry out any damp areas.

Bedding Management for Odor Control

Bedding serves several purposes in a sheep barn. It provides a soft, dry surface for sheep to lie on. It insulates them from cold floors. And it absorbs moisture from urine and manure. Proper bedding management is one of the most effective ways to control odor.

Choosing Bedding Material

Straw is the most common bedding for sheep. It is affordable, widely available, and provides good insulation. Wheat straw and barley straw are the most common types. Oat straw is softer but more expensive. Straw breaks down relatively quickly, so it needs to be replenished often.

Wood shavings are highly absorbent and last longer than straw. They are a good choice for lambing pens and for barns where you want to reduce the frequency of bedding changes. Pine shavings are the most common type. Avoid shavings from black walnut, which can be toxic to livestock.

Sawdust is the most absorbent option but is dusty. It can be dusty when it is applied and can contribute to respiratory problems in sheep and humans. If you use sawdust, look for coarse sawdust rather than fine dust.

Recycled paper bedding is absorbent and dust free. It is made from shredded newspaper and other paper products. It is more expensive than straw but works well for sheep with respiratory issues.

The Deep Bedding System

The deep bedding system, also called the compost bedded pack, is popular for sheep barns. In this system, you add fresh bedding on top of old bedding without removing the manure. The bedding pack builds up over weeks or months. If managed correctly, the pack stays dry on top and does not smell.

The key to a successful bedding pack is carbon to nitrogen ratio. Bedding provides carbon. Manure and urine provide nitrogen. A ratio of about 30 parts carbon to 1 part nitrogen is ideal for composting. Straw and wood shavings have a high carbon content. Manure has a high nitrogen content.

To maintain the right balance, add fresh bedding regularly. A common schedule is to add a new layer of bedding every few days. The amount depends on the number of sheep and the amount of manure they produce. A good starting point is 1 to 2 pounds of bedding per sheep per day. Adjust based on how wet the pack looks and smells.

The pack should be stirred or turned occasionally to incorporate oxygen and promote composting. This can be done with a tractor and a tiller attachment or with a pitchfork in smaller barns. Turning the pack helps it stay dry and reduces odor.

The Cleanout Schedule

Eventually the bedding pack must be removed. The frequency depends on the size of the barn, the number of sheep, and the type of bedding. A small barn with a few sheep may go several months between cleanouts. A large barn with many sheep may need cleaning every few weeks.

Signs that the pack needs to be removed include:

• The pack is wet and soggy on top
• The pack smells strongly of ammonia
• Sheep are lying in manure rather than on bedding
• The pack has built up so high that sheep cannot stand comfortably

When you clean out the pack, remove all of it down to the floor. This is a good time to inspect the floor for damage and to disinfect the barn. Allow the floor to dry completely before adding fresh bedding.

Manure Management Systems

The way you handle manure from your sheep barn affects odor inside the barn and around your farm. A well designed manure management system removes manure quickly and stores it in a way that minimizes odor.

Scraping Systems

The simplest manure management system is scraping. You use a tractor with a scraper blade to push manure and soiled bedding out of the pens. This works well in barns with solid floors. The manure is pushed to a collection area, then loaded into a spreader or storage pile.

Scraping should be done regularly. Daily scraping is ideal for heavily stocked pens. At minimum, scrape pens every few days. The longer manure sits in the pen, the more ammonia it produces.

Slatted Floors

Slatted floors allow manure to fall through gaps into a pit below. The sheep stand on wooden or concrete slats with gaps of about half an inch to three quarters of an inch. Manure and urine fall through the gaps into a storage pit.

Slatted floors keep the surface of the pen clean and dry. This reduces odor inside the barn significantly. The manure pit below can be emptied with a pump or a vacuum tanker. The main drawback is the cost of installing slatted floors and the need for proper pit management to prevent gas buildup.

Manure Storage

How you store manure affects odor around the barn. A pile of fresh manure produces strong odors as it decomposes. Covered storage reduces odor and prevents rain from running through the pile. If you store manure outside, keep it as far from the barn and neighboring properties as practical.

Composting manure is an effective way to reduce odor and produce a useful soil amendment. A properly managed compost pile heats up and breaks down quickly. The finished compost has little odor and is easier to spread than fresh manure.

Common Mistakes in Odor Control

Several common mistakes cause persistent odor problems in sheep barns. Recognizing these can help you fix the issue quickly.

Blocking the Ridge Vent

The ridge vent is the most important outlet in a naturally ventilated barn. Some farmers close it in winter to keep the barn warm. This traps moisture and ammonia inside. The barn becomes damp and smelly, and the sheep suffer from respiratory irritation.

Keep the ridge vent open year round. In winter, adjust the sidewall inlets to control air flow. The ridge vent should always be open at least a few inches to allow moisture to escape.

Overstocking the Barn

Too many sheep in a barn means too much manure and moisture. The ventilation system cannot keep up with the load. Overstocked barns are always damp and smelly, no matter how much bedding you add.

Follow recommended stocking rates for your barn. A general guideline is 15 to 20 square feet of floor space per ewe in a bedded barn. Lambing pens need more space. If the barn is crowded, consider moving some sheep to outdoor lots or another building.

Using Wet Bedding

Bedding that is stored outside and gets rained on is wet before it ever reaches the barn. Wet bedding does not absorb moisture from urine and manure. It just adds more moisture to the pack.

Store bedding under cover. Keep straw bales and shavings piles covered with a tarp or in a shed. If bedding gets wet, spread it out to dry before using it, or use it in areas where the pack is dry.

Ignoring Water Leaks

A leaky water trough or pipe adds gallons of water to the bedding every day. This makes the bedding pack wet and increases ammonia production. Check water systems regularly and fix leaks promptly.

Cleaning Too Thoroughly in Winter

It seems counterintuitive, but cleaning a barn too thoroughly in winter can make odor worse. When you remove all the bedding, you expose the cold, damp floor. The next batch of bedding absorbs moisture from the floor and becomes wet quickly.

In winter, leave a thin layer of old bedding on the floor when you clean. This provides a dry base for fresh bedding. Save the deep clean for warmer weather when the barn can dry out quickly.

Decision Thresholds and When to Act

Knowing when to take action is important. Some odor problems can be fixed with simple adjustments. Others require major changes.

Immediate Action Required

Take immediate action if you notice any of these signs:

• Ammonia smell makes your eyes water when you enter the barn
• Sheep are coughing or showing signs of respiratory distress
• Relative humidity stays above 80 percent for more than a day
• The bedding pack is visibly wet and soggy
• Sheep are lying in manure because there is no dry bedding

These signs indicate that the current management system is failing. Increase ventilation immediately. Add fresh bedding to provide a dry surface. If sheep show signs of respiratory illness, move them to fresh air and contact a veterinarian.

Short Term Action

Take action within a few days if you notice:

• A persistent ammonia smell that is noticeable but not overpowering
• Relative humidity between 70 and 80 percent
• The bedding pack is damp but not soggy
• Sheep are coughing occasionally

These signs indicate that the barn needs adjustments. Increase the ventilation rate. Add more bedding. Check for water leaks and fix them. Review your cleaning schedule and make sure it is adequate.

Long Term Planning

Plan for changes over the next few months if you notice:

• Odor problems recur every winter
• The barn feels stuffy even when vents are open
• Sheep have frequent respiratory infections
• Bedding use is much higher than expected

These patterns suggest a design problem with the barn or a systemic management issue. Consider adding mechanical ventilation, redesigning the air inlets, or changing your bedding system. Consult with a local extension agent or agricultural engineer for advice.

Monitoring and Recordkeeping

Keeping records of barn conditions helps you spot problems before they become serious. A simple log of temperature, humidity, ammonia levels, and bedding changes can reveal patterns that you might otherwise miss.

What to Record

Record the following information at least once a week:

• Date and time
• Outside temperature and weather conditions
• Inside temperature
• Relative humidity
• Ammonia level
• Number of sheep in the barn
• Bedding additions
• Any health problems observed

More frequent monitoring is useful during extreme weather or when you notice problems. Daily monitoring is recommended during lambing season when the barn is stocked heavily.

Using Your Records

Review your records monthly. Look for patterns. Does the ammonia level rise when the temperature drops? Does humidity spike after you clean the barn? Do respiratory problems follow periods of high ammonia?

Use your records to make adjustments. If ammonia levels are consistently high in winter, increase the minimum ventilation rate. If humidity stays high, add more bedding or improve drainage. If problems occur at specific times of day, adjust your management schedule.

Digital Tools

Several apps and software programs can help with recordkeeping. Simple spreadsheet programs work well. Some farmers use sensors that log data automatically and send alerts when levels are out of range. These systems are becoming more affordable and are worth considering for larger operations.

When to Call a Veterinarian or Extension Agent

Most odor problems can be solved with management changes. But some situations require professional help.

Call a Veterinarian

Call a veterinarian if you see signs of respiratory illness in your flock. These include:

• Coughing that persists for more than a day
• Nasal discharge
• Rapid or labored breathing
• Loss of appetite
• Lethargy or depression
• Fever

Pneumonia can spread quickly through a flock. Early treatment improves the chances of recovery. Your veterinarian can diagnose the cause and recommend appropriate treatment. They can also help you determine whether the barn environment is contributing to the problem.

Call an Extension Agent

Call your local extension agent if you need help with barn design, ventilation systems, or manure management. Extension agents can provide advice on:

• Designing or modifying a barn for better ventilation
• Choosing the right ventilation system for your climate
• Developing a manure management plan
• Managing bedding packs for composting
• Meeting environmental regulations for manure storage

Extension agents have access to research based information and can connect you with agricultural engineers and other specialists. They can also help you determine whether your barn meets local regulations for air quality and manure management.

Frequently Asked Questions

How much ammonia is too much in a sheep barn?

Ammonia levels above 25 parts per million are unhealthy for sheep. At this level, the ammonia irritates the respiratory tract and eyes. Levels above 50 ppm cause more serious irritation and can reduce feed intake. If you can smell ammonia when you walk into the barn, the level is probably above 10 ppm. If it makes your eyes water, it is above 25 ppm and you need to increase ventilation immediately.

Can I use a fan to control odor in my sheep barn?

Yes. Fans are an effective way to control odor, especially in winter when natural ventilation is limited. Use exhaust fans to pull stale air out of the barn and install inlets on the opposite wall to bring in fresh air. A minimum ventilation rate of 20 to 30 cubic feet per minute per ewe is recommended for winter. Increase the rate as the weather warms.

How often should I add fresh bedding to my sheep barn?

The frequency depends on the number of sheep, the type of bedding, and the season. A good starting point is to add 1 to 2 pounds of bedding per sheep per day. Add more in winter and during wet weather. The top layer of bedding should always be dry. If the bedding is wet or the barn smells of ammonia, add more bedding and increase ventilation.

What is the best bedding for controlling odor in a sheep barn?

Wood shavings are the most effective at controlling odor because they absorb more moisture than straw. Pine shavings are a common choice. Straw is cheaper but breaks down faster and needs to be replenished more often. Recycled paper bedding is also absorbent and dust free. The best choice depends on availability, cost, and your specific barn conditions.

Why does my sheep barn smell worse in winter?

Winter odor problems are caused by reduced ventilation. Farmers close doors and vents to keep the barn warm, which traps moisture and ammonia inside. The solution is to maintain some ventilation even in cold weather. Keep the ridge vent open and adjust sidewall inlets to provide fresh air without creating drafts. A properly ventilated barn can be warm and dry at the same time.

How do I get rid of ammonia smell in my sheep barn fast?

The fastest way to reduce ammonia smell is to increase ventilation. Open doors and vents to bring in fresh air. Add fresh bedding to absorb moisture from the pack. Remove wet bedding and manure from the pens. If the problem is severe, move the sheep to a different area and clean the barn thoroughly. Ammonia levels should drop quickly once air flow improves and moisture is removed.

Should I use lime or other products to control barn odor?

Hydrated lime can be used on barn floors to reduce odor and kill bacteria. Apply a thin layer to the floor before adding bedding. Do not use lime directly on sheep, as it can cause skin irritation. Commercial odor control products are available but vary in effectiveness. The most reliable approach is to manage moisture and ventilation properly. Products that mask odors are not a substitute for good management.

Can poor barn air quality cause pneumonia in sheep?

Yes. Ammonia and dust irritate the respiratory tract and damage the natural defenses of the lungs. This makes sheep more susceptible to bacterial and viral pneumonia. Lambs are especially vulnerable. Maintaining good air quality is one of the most important things you can do to prevent respiratory disease in your flock.

Related Farming Guides

This section will be populated with links to related farming guides on sheep health, barn design, and flock management.

Related Clinical & Scientific Guides

• Sheep Grazing Lease: Terms, Rates, and Legal Considerations
• Sheep Breed Selection for Meat, Wool, Dairy, and Low-Input Systems
• Sheep Barn Flooring for Hoof Health: Best Materials and Practices

References

• American Consortium for Small Ruminant Parasite Control (ACSRPC): https://www.wormx.info/
• USDA APHIS Sheep Health: https://www.aphis.usda.gov/livestock-poultry-disease/sheep-goats
• FAO Sheep and Goat Production: https://www.fao.org/animal-production/en/
• FAO Animal Production and Health: https://www.fao.org/animal-production/en/
• WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.