The North American horse deal is 25,000 race horses born each year.  Maybe 100 become breeders and money winners.  The rest?

Canada has large horse farms,  hundreds of stalls of mares with foal,  a huge latex bag collecting their urine,  to be made in Premarin,  the menopause drug of efficacy and choice.  Can't do that in U.S.  PETA won't allow it.  So what happens to the offspring?  Most end up in sandwich meat or on the plate in Europe.

And of course,  Mexico,  which has horse slaughter to add to all that dies in that country.  

So wild horses reproduce at 20% per year.  Herds double in size every four years.  There was a decade of wild horse adoption.  BLM managers culled herds to make them stronger and better conformation, color.  The rest went to auction.  The ones that didn't sell end up on one of the several large horse pastures in the Plains states to live,  over 50,000 on pasture today.  Eating at U.S. Govt expense for what purpose?

Wild horses are a budget item.  Red ink.