Ok.
This is a very broad question, with many answers. But ill make a start. Im sure others will have a lot to add.
You need to keep your mare in good condition, not too fat and certainly not too thin. I do actually like to have my mares a little heavier when in foal, but not to the point of being obese or unhealthy. Just an "extra layer".
Keep her feet done, as she puts on weight and gets bigger, it puts more stress on her feet and legs. So make sure you keep up with her trimming.
I like to give a good mare and foal pellet throughout the pregnancy, and lactation. I also keep the mare on a mare and foal supplement. In Australia we have "Cell grow" that i love. Not sure what you have over there, but im sure someone can recommend something.
When the mare gets closer to her foaling date (around day 300 i think is good, but earlier if you think she is progressing quicker), bring her into her own space, a safe foaling yard/paddock/stable so she can start getting immunity to the new surroundings to pass on to her foal.
Most mares foal between 320 - 340 days. About 75% of mine have foaled between 320 - 330 days, and ALL have foaled between 310-335. Mares can go earlier or much later. I would work out her due date on 330 days from the last date she was bred, and work with that.
I wont talk about vaccinations, as im sure the requirements for you will be totally different to here. Ill let someone else touch on that one for you.
When she is closer to foaling, start monitoring her closely. Do all that you can to be in attendance at foaling time. Many a foal has needlessly died because of something as simple as not getting out of the sack after birth (often all you will have to do while attending a birth is break the sack once the foal is out). Worse still, you could lose the mare and foal if the foal gets stuck/isnt presented correctly, and noone is in attendance to help.
Do as much research and reading as you can on the signs of foaling, what to expect in a normal foaling, and what you can do if a foaling isnt going as it should. Notify your vet closer to foaling that they may get a late night phone call, and keep their number on hand.
Mares need plenty of good feed after foaling, and you will need to up her feed to cater for the milk production. After a few days, the foal may start showing an interest in the mares feed. This is fine. I do like to wet all my horses feeds down, so i just make it a tad wetter while the foal is getting used to eating it to make it softer.
I turn my mares and foals out with the rest of the herd after about 6-7 days, but sometimes i wait longer if the mare is too protective, or if there is bad weather and i want to keep the foal in and dry/warm.
The first little while, the foal cannot regulate their body temperature real well, as they have no excess body fat. So its important to keep them warm if needed (or cool) so they arent wasting their energy trying to keep themselves warm.
Ok... ill leave it at that for the moment. Im sure there will be lots added & other opinions. I need to finish dinner
