I think you need to put more info, the feed may be fine for a poor doer but for a native it could be far too much, a brood mare should not be allowed to get too fat so her condition needs to be taken into account when deciding what to feed, most will need less before foaling than they will afterwards once they are lactating but still shouldn't be getting too much, if they are on decent grass a top up of vits and mins could well be enough.
It’s a balancing act and horse dependant. You want quality not quantity. You don’t want an obese mare trying to give birth to an overdone foal.
None of the mares I’m involved with get stud mixes. They get ad-lib haylage/grass and a stud balancer. If they need topping up from that they get a fibre cube.
Thank you. I asked the vet ( he was down yesterday to check on the foal). He did that the normal groan will be good along with a little it of the lactating mare feed. He did a ultrasound and guessed she had about a month.