These days if they're not fast enough race horses are supposedly not sent to the knackery. Owners and trainers found to have sent ex race horses to the knackery face disqualification and horses can't be sold for less than $700 (from memory) to prevent agents of knackeries buying race horses through commercial sales. That sounds virtuous, except that it doesn't remove demand for meat. Presumably other animals are now killed in place of retired race horses to fill the demand for meat.
