https://en.wikipedia.org/wiki/Red_junglefowl

While the ancestors of horses have been hunted to extinction a long time ago, the wild cows that have existed in Europe until a few hundred years ago (a.k.a. aurochs) and the wild pigs that still exist have remained genetically close enough to their domesticated relatives that frequent interbreeding between them has happened, during the many millennia since the domesticated cows and pigs have been brought to Europe.

The chicken breeds that were previously widespread, before their replacement with the optimized modern breeds, had a behavior very similar to their distant South-Asian ancestors and they were quite capable of taking care of themselves, when given an appropriate space.

There is no relationship between vegans and industrial farming.

Nevertheless, nobody could be truly vegan centuries ago, without acquiring serious health problems. Veganism has become possible only after the development of the industrial technologies required for the production of the supplements needed to provide various essential nutrients, vitamins and minerals that either do not exist in plant food or they exist in too small quantities and which either cannot be produced by humans at all or they can be produced, but in too small quantities for ensuring a good health.