An archaic plural for ‘cows’, used here as Orlando gets carried away on a roller-coaster of metaphors.
‘She likened the hills to ramparts, to the breasts of doves, and the flanks of kine. She compared the flowers to enamel and the turf to Turkey rugs worn thin. Trees were withered hags, and sheep were grey boulders. Everything, in fact, was something else.’
Source: Virginia Woolf, Orlando, ed. Rachel Bowlby, Oxford: World’s Classics, 1992, p. 138