Wow, what an incredible place to retire. It's gorgeous! Congratulations on your ranch! :mrgreen:
Thanks! In answer to your question on horse size, I think it's both genetics and nutrition. The general attitude on large livestock here is that it should eat grass and reproduce. At the Ag stores here there is a wide variety of wonder feeds for chickens and hogs, animals with a high expected ROI. Sometimes there are feeds for cattle, but no feeds specifically for horses. And few to no people who would spend money on feeding a horse. I have found that many tropical grasses are difficult to digest. Ruminants can do well on them, if they get enough, but horses are another matter.
Natural selection will favor the horse that can survive on coarse fodder. That tends to be smaller bodied animals. I've started one hillside in koronivia grass that I got from the Department of Agriculture research farm. More nutritious than the grasses already on the place. But that will take years to reach full potential. Fortunately for me, I'm a small framed, scrawny hillbilly. I'm shooting for 14 hands, but can get by with slightly smaller. The same can't be said if I want to take my full size American or European friends riding.
But, I knew that going in. It's an adventure I signed up for.