Yes, your right the total peace time requirement for horses will be roughly the same regardless of who breeds them. A military breeding program might improve the quality but at the expense of breeders producing horses for the wider economy. It might help with bean counting but once a war starts the remounts will be swiftly used up and the overall situation and the need for horse flesh will be the same.The Germans had a subsidised stud system in place before the war.
The big question is if British army wants to have a stud service that's efficient it will probably crowd out civilian horse breeders. Yes the horses may be a little more appropriate for army use but the total capacity will be similar.
It's my understanding that the reason behind the level of strain on the horses was due to railway failures.
I wonder if stockpiles of light rail for the army engineeers would be a more efficient way to do stuff.
A recognition of the need to move supplies from the rail head to he front and as you suggest a stockpile of narrow gauge light railway that could be swiftly layed behind the army be a better investment.
I suppose the big question would this have helped in the Boer war, because if it wouldn't then it's a solution for a need that didn't exist.
I need to remember when looking at numbers of horses just how different 1903 was and the national dependency on the horse for tran and working the land.
Thanks Dave