Bava Batra 36: No Presumption of Ownership for Slaves (or Livestock)
A case of claimants with regard to slaves, for which the Gemara draws a parallel to movable property -- for which a presumption of ownership does not take hold after 3 years. Though it may well apply for slave who is a baby? Also, the abbreviated time or an irrigated field. Plus, plowing your land -- isn't that also chazakah? Shouldn't it be?