I was in a commercial broiler chicken farm today.
Those 19 days chickens are suffering respiratory disturbance and leg weakness.
It is not normal to have a respiratory noise in that age.
The farmer will always think that is a form of an microorganism infection.
My suggestion : Before you are suspicious on a disease infection, make sure that your farm management is under good control.
What is happening in this farm :
This farm has a high level of ammonia smell inside the chicken house --> it explains where they gets the respiratory disturbance. Leg weakness is from the ammonia burn from the bedding or litter..
So what makes this ammonia ?
This ammonia is coming from the NH3 of the chicken droppings, the more chicken have watery droppings in the bedding material, it will form Ammonia.
So what makes this watery droppings?
I checked the temperature (HOT), the relative humidity (DRY), and chicken feed (Yes, they switched the feed raw material for a day yesterday). That explains all. Hot temp and dry humidity will makes the chickens open their beak (panting), they will drink more. The feed change will disturb their digestive system balance.
Okay, one case solved today.