The Collaborative International Dictionary of English v.0.48:

Damage feasant \Dam"age fea`sant\ [OF. damage + F. faisant
   doing, p. pr. See Feasible.] (Law)
   Doing injury; trespassing, as cattle. --Blackstone.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

DAMAGE FEASANT, torts. This is a corruption of the French words faisant
dommage, and signifies doing damage. This term is usually applied to the
injury which animals belonging to one person do upon the land of another, by
feeding there, treading down his grass, corn, or other production of the
earth. 3 Bl. Com. 6; Co. Litt. 142, 161; Com. Dig. Pleader, 3 M 26. By the
common law, a distress of animals or things damage feasant is allowed. Cow.
Inst. 230; Gilb. on Distress and Replevin, 21. It was also allowed by the
ancient customs of France. 11 Toull. 402 Repertoire de Jurisprudence,
Merlin, au mot Fourriere; 1 Fournel, Traits de Voisinage, au mot Abandon.
Vide Animals.