Given the broad scope of the current Horse Ranch rework, all information related to horses that is not recent should be considered obsolete. For upgrade information about horse ranch buildings see the Horse Ranch Building Upgrade Information spreadsheet, or the “New” section of the German Wiki’s Horse Ranch page.
Official guides for Part 1 and Part 2 of the rework can be found on the Community Hub (1, 2), and on Discord (2).
The Tertiary Horse Information spreadsheet contains tables of data about the new functions on the Horse Ranch.