off one's feed

prepositional phrase2

1. •
   Not eating normally.

   • "Nothing serious," the veterinarian added. "He was just off his feed a trifle." — 1915
2. •
   Rather unwell, especially with a reduced or altered appetite; somewhat disoriented or disconcerted.

   • “He wos took wery bad one arternoon, arter having been off his feed, and wery shaky on his legs for some veeks.” — 1841