(来学网)某1000只肉鸡群,4周内发病500只,死亡300只。该病的病死率是
  • A.
    (来学网)20%
  • B.
    (来学网)30%
  • C.
    (来学网)40%
  • D.
    (来学网)50%
  • E.
    (来学网)60%