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From OED online: SHED: ""To separate, divide. Now only dial., chiefly in farming uses: To separate (lambs) from the ewes, or (calves) from the cows; to separate (cattle, sheep) from the herd or flock. to shed the shanks (Sc.): to set the legs apart."" The first date they have for this use is c.1000, but I can't read it.  ."