Cassie, if Suzie looks as good as she did in her pics last week, then you are doing fine!!
I would still get rid of that chaff - to dangerous for foals if they start digging into Momma's food, plus I have no idea how much your 'half biscuit' of hay actually weighs, but wouldn't think it nearly enough to keep Suzie's system ticking over all night?? Plus little Finn must be helping himself by now!
Jenny, I agree with Bree - ditch the chaff! Once she foals you do not want anything in her feed bowl that might cause a problem to the foal (choke etc), which is why we change all our mares on to a very small balancer pellet or a mare and foal feed that is small pellets/or will disolve on contact with water (saliva). Of course my girls are on heavily grassed paddocks all day, but they still get hay ad lib throughout the night - how much hay are you feeding as from your pics, you dont have a lot of grass available?
Not sure why you are feeding a mare and WEANLING feed - or do you mean "foal"? If your stud feed is made up of fairly small pellets and they disolve easily, then I would get rid of your other feeds and just use them and plenty of hay (plus your extra vitamins as you are not feeding enough of the stud feed to provide all these).
I dont agree with your vet when she says you are feeding way to much - yes maybe, if you had access to really good grass all day! But as I said, keep the supply of hay going and perhaps up your mare (stud) feed to 4 cups per day (getting rid of the other food) or find a good mare and foal food and give 4 cups of that. Again, as Bree said - keep it simple!!
Hoping those results come back positive.
ps. Have I spelt disolve correctly? It doesn't look right and my brain just wont work this morning! LOL!!