I can't comment specifically on the 'mare & foal' grain she's getting because you need to tell what exactly it is & the amount(weight) daily would be helpful too.
What's the muscle supp for?
Also 50lb of hay seems like a lot per day. Horses should get approx 2.5-3%bwt daily in roughage. I gather with her eating that much, she's not paddocked at all? I'd be looking to find somewhere that she was turned out 24/7(or close) with other horses, so she can grow up being a horse. This is also for health reasons.
The place I'm moving to does have turn out 24/7. They have access to stalls though, I gather.
She's eating: Blue Seal Mare and Foal feed. BO says she eats 6 pounds a day.
She says Kiera eats 45-50 pounds of hay per day. She's been keeping them inside "due to flies and the heat" during the day, and letting them out to pasture at night. (Kiera is pastured with the majority of the other horses, she's a yearling, and bottom of the totem pole, with some scars to prove it
)The BO has always been that way with any weather she considers too harsh...I'm really glad that Kiera will be out all the time, she seems a LOT(!) happier being outside, and she's seems pissy when she is kept stalled.
Oh and she doesn't need the muscle up, she just hasn't run out yet xD I bought it when I first got my girl, because she was full of worms and probably didn't receive great nutrition the first five months of her life...I figured at the time that she could use all the help she could get TBH.
Also, TY TY TY for replying!!!!!!!!!!!