Cheese maker Jonathan Crump, from Gloucestershire, noticed the calf was missing on 2 September when it failed to return with its mother.
But he was "totally amazed" when the 10-day-old calf - now named Sinky - was found by ramblers in a metre-deep hole.
He said: "I never imagined a cow could live for those days without any food."
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The rare Gloucester calf was discovered neck deep in "quite a big hole" by walkers Dan Rawlings, 37, and Tom Lewis, 35.
Mr Rawlings said: "We were just cutting across the fields and spotted something in a hole.
"At first we thought it was a badger, but when we looked closer we realised it was a calf."
After rushing to the farmhouse to raise the alarm, they returned to find the young animal "trying to get out".
"All it needed was a little help and it got out. All the cows came running over moo-ing, so we backed off," Mr Rawlings said.
"It was lovely to see the mum and calf reunited."
Mr Crump, who has a milking herd of 35 cows near Standish, said he had searched his farm for the missing animal but had given it up for dead.
"I'm very grateful they found it. They were actually lost, so it's great they found it," he said.
Sinky, now being fed a course of electrolytes in a bid to combat dehydration, looks set to make a full recovery.
It is thought the hole was created by an underground spring.
A farmer who gave up a missing calf for dead said he was astonished when it was found nine days later with its head sticking out of a sink hole.