My honest opinion....wayyyyy too young for weaning. But that's another story
I would ask the breeder what they are currently feeding.
Weanling, yearling, adult, senior, they need, first and foremost, ROUGHAGE. Hay, grass. Without enough if that, you'll set yourself up for a lot of trouble later.
Depending on the hay and/ or grass available, I would choose a vitamin/ mineral supplement for weanlings, if not feeding alfalfa, some other form of protein and calcium.
Grain or sweetfeed only if absolutely needed, and certainly not as the main feed.