He finds the caecotrophs revolting, consisting as they do of semi-digested herbage, discharged through the anus and reswallowed two or three times a week.

The answer appears on the fifty-second page of the book.

Jack was received with a hearty welcome by his uncle, for he came in pudding-time, and was invited to dinner; […]

I asked the doctor if I was long for this world (likely to live a long time)