Poultry science: Ventilation and Backyard flock management

[Rangergord]

I am building an insulated winter coop and wondered just what the proper humidity for chickens was. Humidity is always relative to temperature and I live in a cold dry climate. Many others live in warm humid climates so there is no one simple answer to the question. This paper shows the relationship between relative humidity and air quality. The archive is full of other poultry science papers on backyard flock management as well as commercial operations.

https://www.poultryventilation.com/node/4925

 

[Rangergord]

Knowing how much to ventilate during cold weather is crucial to a poultry producer’s bottom line. Ventilating too little can lead to poor air/litter quality, resulting in bird health and performance issues. Ventilating too much can lead to drafty, dusty conditions and high heating costs. To best determine minimum ventilation fan runtime, farm managers should ideally monitor the three most important air quality variables: carbon dioxide, ammonia and relative humidity. Carbon dioxide is produced by both the birds and the house’s heating system. High carbon dioxide concentrations can lead to lethargic chicks and reduced weight gains and therefore should be kept below 5,000 ppm (ideally below 3,500 ppm). High ammonia concentrations can lead to poor feed conversions, reduced weight gains, and increased susceptibility to disease. In order to maximize bird performance and health, ammonia concentrations must be kept below 30 ppm (ideally below than 20 ppm) throughout the flock. Last but not least, relative humidity should be kept between 50 and 70%. Lower relative humidities will tend to result in a dusty house and high heating costs while higher relative humidities can lead to wet litter and high ammonia concentrations. Having meters to measure carbon dioxide, ammonia and relative humidity allows farm managers to set their minimum ventilation fans so they ventilate just enough to maintain proper air quality without over ventilating and driving up heating costs.

As you might suspect the problem with measuring all three air quality variables is cost. A reasonably accurate and reliable carbon dioxide meter typically costs between $300 and $500. Most ammonia meters used in the poultry industry cost between $500 and $1,000. The problem is their accuracy is questionable, require frequent calibration, have sensors that typically have to be replaced yearly and they generally cannot be left in a house for extended periods. On a more positive note, monitoring relative humidity is a fairly simple and inexpensive proposition. A reasonably accurate relative humidity meter that is capable of recording daily maximum and minimum relative humidity typically costs between $50 and $150. A relative humidity sensor can be added to most controllers for less than $300 and enables the controller, if the producer desires, to continually make changes to minimum ventilation rates to ensure the relative humidity stays within a specified range.

Though having access to all three types of meters would be helpful, realistically the only meter farm managers need to assess overall poultry house air quality is one that measures relative humidity. This is because for most of a cold weather flock, ammonia and carbon dioxide concentrations tend to closely follow relative humidity. That is, if the relative humidity is high, carbon dioxide and ammonia levels will tend to be high. If the relative humidity is low, carbon dioxide and ammonia levels will tend to be low as well. The close relationship among ammonia, carbon dioxide and relative humidity tends to be strongest with older birds and weakest during the first week or two of the flock. This is due to the substantial amount of carbon dioxide produced by most heating systems and the use of litter treatments which can result in a situation where the relative humidity is low and carbon dioxide high or the relative humidity is high and ammonia concentrations are low.

 

[3KillerBs]

Interesting.

I'm not sure how managing conditions for an intensively-managed broiler house lines up with a backyard setup, but it should help people understand the critical importance of good ventilation for our birds' health.

 

[U_Stormcrow]

How big a coop are you building, that commercially sized heating and ventilation systems are a concern for you? and why would you try to engineer it yourself, when you can just check out a local commercial producer (or seek guidance from the vendor you are supplying) for what works best in the region. Commercial poultry building ventilation needs (and building design & orientation) vary by region and climate.

For they typical backyard owner, of the typical backyard flock, these considerations are overkill (and except in the most extreme of environments, or the most brittle of birds, insulation isn't recommended either).

Well ventilated, dry, draft free. All season, every season. If you have a naturally dry, cold environment, you are already starting off ahead of most of us.

 

[Rangergord]

Interesting.

I'm not sure how managing conditions for an intensively-managed broiler house lines up with a backyard setup, but it should help people understand the critical importance of good ventilation for our birds' health.

This particular paper is not directly applicable to backyard but I am proficient at reading between the lines and figuring it out for myself. The Archive in the menu is packed with paper directed at Backyard flocks.

 

[Rangergord]

How big a coop are you building, that commercially sized heating and ventilation systems are a concern for you? and why would you try to engineer it yourself, when you can just check out a local commercial producer (or seek guidance from the vendor you are supplying) for what works best in the region. Commercial poultry building ventilation needs (and building design & orientation) vary by region and climate.

For they typical backyard owner, of the typical backyard flock, these considerations are overkill (and except in the most extreme of environments, or the most brittle of birds, insulation isn't recommended either).

Well ventilated, dry, draft free. All season, every season. If you have a naturally dry, cold environment, you are already starting off ahead of most of us.

8X8 LoL! I live In the subarctic where there are no poultry experts and I prefer to understand things for myself rather than rely on some engineers opinion. Many people have no idea just how cold it is here. Uninsulated houses from my bitter experience simply are not adequate. Not planning on heating the coop but a water heater, light and probably a small heat pad panel will be included.

 

[U_Stormcrow]

8X8 LoL! I live In the subarctic where there are no poultry experts and I prefer to understand things for myself rather than rely on some engineers opinion. Many people have no idea just how cold it is here. Uninsulated houses from my bitter experience simply are not adequate. Not planning on heating the coop but a water heater, light and probably a small heat pad panel will be included.

I appreciate the desire to understand for oneself. We have posters raising birds in unheated coops at -30F, -40F in Canada and Alaska. I'll let them take it from here, but you may find these links useful (and yes, I can imagine you can't just drive a few miles to see a nearby commercial poultry op in your region!)

This is by the well named @Alaskan https://www.backyardchickens.com/articles/cold-weather-poultry-housing-and-care.72010/

and this may prove reassuring
https://www.backyardchickens.com/threads/how-cold-is-too-cold-check-this-out.1345546/

 

[Rangergord]

I appreciate the desire to understand for oneself. We have posters raising birds in unheated coops at -30F, -40F in Canada and Alaska. I'll let them take it from here, but you may find these links useful (and yes, I can imagine you can't just drive a few miles to see a nearby commercial poultry op in your region!)

This is by the well named @Alaskan https://www.backyardchickens.com/articles/cold-weather-poultry-housing-and-care.72010/

and this may prove reassuring
https://www.backyardchickens.com/threads/how-cold-is-too-cold-check-this-out.1345546/

Thanks I have already read those links TWICE! There are some commercial laying ops two to three hours away from me they use heated insulated barns. I can’t afford to heat mine! There is a big difference between chickens surviving a few cold nights and chickens thriving productively during six months of subarctic winter. I also will have a covered run outside the coop because wind and snow is extreme.

 

[U_Stormcrow]

Thanks I have already read those links TWICE! There are some commercial laying ops two to three hours away from me they use heated insulated barns. I can’t afford to heat mine! There is a big difference between chickens surviving a few cold nights and chickens thriving productively during six months of subarctic winter. I also will have a covered run outside the coop because wind and snow is extreme.

Light will be your issue, so they don't stop laying.

Can you use waste heat/light from your own home to support the birds? EIther by use of a shared wall, or a heat exchange system with your (i assume) wood-burning stove?

 

[Rangergord]

Light will be your issue, so they don't stop laying.

Can you use waste heat/light from your own home to support the birds? EIther by use of a shared wall, or a heat exchange system with your (i assume) wood-burning stove?

For sure it already is. I have three hens in an uninsulated but covered tractor. So I am in a race to build a winter coop. I have had them in the tractor up till mid November some years, end of October in others. No such luck on sharing my house heat. They are getting part of my firewood shed though. I will have the roof and half the walls up by tomorrow.