I don't buy anything over 21% (21% and 22% are great dairy percents, but can get too hot for horses) and even then I am extremly cautious as I prefer 18/19% as a small supplement now that my horse main food source is bermuda-timothy.
I prefer 3rd and 4th cuttings if there is a good year. I avoid 1st and late cuttings due to the blister bettles here in the south if I don't buy out of state. When I lived in Cali (horses grew up on alfalfa as main feed), I would get the 2nd and third cuttings as a 4th was not common where I lived).
At 30% (which is higher than the 28% I have only heard of), you will have a high risk of health issues such as founder, intestinal stones etc.
Contact your vet and specialize the feed for your horses individually, especially if you change their feed dramatically.