Thank you!I posted studies that discuss cold stress in birds because a lot of people don’t feel cold stress is an issue, but I think people are stuck on the 50F temp. Here is Dr. Mozisek discussing it:
I think his perception is badly skewed by the fact that he lives in Texas. It also sounds to me like he is giving advice for people in his climate, not for people in all climates.
For example, he can talk about closing up a coop and compromising ventilation for just one or two cold nights. He says that you would not want to do this for extended lengths of time. But his rare nights of cold temperatures are what some northern climates see for months on end-- he does not say how to address that situation.
He says that 75 degrees is an optimum temperature for a chicken, and he talks about chickens suffering from the heat at 100 degrees (25 degrees warmer) and suffering from the cold at 50 degrees (25 degrees cooler.) He talks about chicken comfort, and about whether egg production is affected, but he does not talk about the death rate at different temperatures.
When I read some other sources, I would say he is badly wrong to compare those temperatures.
Here is one example of a source talking about heat stress in chickens.
https://extension.umn.edu/poultry-care-and-management/preventing-heat-stress-poultry
It says, "When air temperature increases towards 100 F, the birds’ core body temperatures will increase to lethal temperatures unless relief is provided."
Here is another source:
https://extension.psu.edu/hot-weather-management-of-poultry
It has a chart of various temperatures, and it also says that "survival is a concern" at temperatures over 100 F.
I can't recall ever seeing an account of a healthy adult chicken that died of cold at 50F. Adult chickens only die at that temperature if they have some kind of health problem.
I do not see this video claiming that 50 degrees is dangerous to the life of adult chicken either. It only points out reduced egg production and concerns about chicken comfort.
So temperatures of 100F and 50F are not equally dangerous to a chicken. If we want to compare temperatures that are equally dangerous to chickens, as measured by death or visible injury, we have to move the low end quite a lot colder.
Regarding egg production, studies are generally done on high-production layers in confinement housing. Simply changing the style of housing can make a big difference to the comfort of the chickens, and change the temperatures at which egg laying is affected. (Case in point: a book from 1949 that recommended a particular style of unheated poultry house, and said that laying was unaffected down to 10F. Book is "Practical Poultry Management", 5th Edition, by James E. Rice and Harold E Botsford. I'm thinking of a bit on page 82.)
In that video, he said that feathers do not always keep a chicken warm enough, and he compared it to a person wearing a vest with a little bit of down (but not enough to keep them warm.) He says that chickens do not grow more down to keep warm-- but he talks as if all chickens are the same in that regard. Some chickens do have more feathers, including more down, than other chickens. It's easy enough to check: look at chickens in a mixed-breed flock, especially comparing breeds that are traditionally considered cold-hardy with those that are not. I've butchered quite a few chickens of different breeds, and I've noticed quite a difference in the amount of feathers on them.
For the few days of actual cold that he gets in Texas, with chicken breeds that are not selected for cold tolerance, and individuals that are not adapted to the cold because they have been living in warm conditions, he may be right to provide heat for his birds. But that does not mean all chickens need heat at those temperatures to be healthy or even to be comfortable.
As someone who has spent many years in northern climates, and read the experiences of many other people who also live in northern climates, I think he grossly underestimates the ability of chickens to be healthy, productive, and reasonably comfortable in cold weather.
This has been a very interesting discussion.
