Well I know horse owners in this area that have doubled their numbers in the past year... the mares all foaled
Here in Huntsville I daily drive by about five pastures holding at least fifty horses each. All the horses are owned by the state of Texas, the TDCJ (prisons) to be exact. They have a horse breeding program here as well. Every prison unit has a herd for the guards. When the 'inmates' (not refered to as cons any more) are working the fields (yes Virginia they raise most of their own food at the prisons) mouted armed guards man the perimeter.
They are not suppose to let inmates closer than 30 feet, yet about a year ago one of the guards was pulled from her horse and shanked to death. Still don't understand the 'trustee' status of a lifer in for murder.
I'd say locally there could be a squadron of mounted troops put together in a matter of days. A note on the prison horses. According to my 'source' these horses when broke and trained are trained for gunfire. So all are potential cavalry mounts.