Poultry Sleepy chicks and dual feathers

[Tom]

My chicks start by dropping fethers,looking sleepy,then final stage unable move then die.
The temperatures are okay .
Kindly help

 

[nedward]

Kindly your flock has contacted disease and you must act swifty isolate the sick if possible transfer the healthy to separate unit. Check your feed quality. Administer Esb3 or Tylodoxy.