I may have another take on these type of situations and I may catch some flack but I will post it anyway. Please don't cull your flock based on what information you get from random posts on the internet. I will acknowledge that there is some valuable information offered on this and other sites on the internet but the vast majority of the information is baseless opinions that was formed by other bad information. I'm not trying to attack anyone, I am just saying to what you need to do with any illness like this is contact your state vet like robin416 suggested and talk the situation through with them before you make any rash decision. There is alot of information on the internet also that is geared or aimed at the production poultry industry regarding these illnesses that take a cull everything approach but that is based on the damage that it can do to a billion dollar industry. The same rules may or may not apply to the backyard poultry keeper.
I called my state vet several months ago just to ask about this situation with MG and coryza as I had seen so many post on here telling everyone that if you have one bird that gets the sniffles that you need to cull your whole flock. He told me that it was insane for anyone to cull for those reasons in a backyard flock. He also told me that in his opinion that 90-95% of all backyard poultry carry MG and Coryza and that if there was ever an effort made to erradicate it in the backyard population that it would basically wipe out 90-95% of the backyard chickens in the U.S..
Now, I'm not telling you to do one or the other...I'm just suggesting that you talk it over with your state vet before you do any major decision making about culling any or all of your birds as this is a costly and often times heartbreaking experience.
Do your research, there may be hope...
I called my state vet several months ago just to ask about this situation with MG and coryza as I had seen so many post on here telling everyone that if you have one bird that gets the sniffles that you need to cull your whole flock. He told me that it was insane for anyone to cull for those reasons in a backyard flock. He also told me that in his opinion that 90-95% of all backyard poultry carry MG and Coryza and that if there was ever an effort made to erradicate it in the backyard population that it would basically wipe out 90-95% of the backyard chickens in the U.S..
Now, I'm not telling you to do one or the other...I'm just suggesting that you talk it over with your state vet before you do any major decision making about culling any or all of your birds as this is a costly and often times heartbreaking experience.
Do your research, there may be hope...