Okla. Stat. tit. 66 § 145
Whenever the owner or occupant of any tract of land abutting on any line of railroad within this state shall desire to enclose any such tract of land for the purpose of making a hog, sheep or goat pasture, and shall construct a fence for said purpose about said tract of land on all sides except along the side abutting on such railroad, it shall be the duty of such railroad company to construct a good and sufficient fence not less than four and one-half (4 1/2) feet high, one barbed wire at bottom of such fence immediately above which shall be attached heavy woven wire not less than twenty-eight (28) inches high, and sufficient for the purpose of restraining swine, sheep and goats, with three barbed wires above the same, on the side of such tract, so far as the same extends along the line of such railroad, and maintain the same in good condition, so long as such owner or occupant of such tract may desire to maintain such pasture.
Okla. Stat. tit. 66, § 145