Private property, some bandit tries to steal your cattle on your land you cap it buttox. You can still get hanged in Texas for stealing a horse. (Though that never happens.)
Though in seriousness, a Ranch is a business. So if you go into a ranch and steal then he's taking your cattle, keyword your, in this case the Rancher.
If it were you stealing the cattle then I guess you could make a case for self interest.