The main purpose of this legislation is to change the tax treatment of horses by reducing the time they must be held before qualifying as certain types of assets under the tax code. Specifically, it aims to lower the holding period from the current standard to just 12 months. This change is intended to provide tax benefits to those involved in the horse industry, particularly racehorse owners and breeders. The key provision of this legislation is the amendment to the Internal Revenue Code, which alters the definition of what constitutes a section 1231 asset.