This is true. I’ve also been very worried.
We went through a lousy year like this a while back (in that case, the cause was too much rain rather than too little) and it was rough. I did bump up grain feeds to make sure nutritional needs were being met, and supplemented with pellets and cubes, but it certainly wasn’t ideal.
You do have your work cut out for you, OP, starting in with horses in a year like this!