This is an interesting thread. I love reading everyone's ideas on various subjects, and the subject of weaning really throws up a good discussion.
I think two things are very important - a) the temperament of your mares, and b) your facilities. I also think that if you are having trouble with your mare's milk supply, then you are possibly weaning too early.
Over here in the UK (please correct me if I'm wrong Jane, it has been a few years since I showed a youngster) a foal cannot enter the show ring without its dam until it is over 5 months old, and the clipping of 'young animals' in their birth year is frowned upon. So weaning is generally carried out much later here.
I am very lucky in that I have plenty of room and grass. I wean my foals late, six months or later if the mare is not foaling/due for a late foal the following year.
Once my foals are around 3 months of age, they and their dams get added to my 'mixed' herd of girls. They all then range a 25 acre area of fields, woods, boggy bits, dry bits (!!) and one gorse area with little 'play' paths running through it. In a natural habitat the foals can run and play, have to watch where they put their feet, jump over fallen trees etc etc. They do all this, but at the same time are learning their manners. They learn to respect their elders, they are at the bottom of the 'pecking' order, mixing with their half sisters, full sisters, aunts, cousins etc plus the unrelated mares - all ages from the other foals up to my old retired girl of 28.
By the time they are around 5 months the foals are rarely to be found near their dams, just whizzing back for the odd feed, and can often be found playing together with the yearlings at the opposite end of the area.
When it comes to weaning the hardest thing we have to do is to try and persuade the foals that they DO want to follow their dams out of the fields, and to leave their new friends behind! We have not even caught and haltered these foals by this age - they are wormed and fussed over, will allow us to trim their feet while an 'itchy' spot is scratched, and are so over friendly they are total pests!
Having got everyone sorted, we simply lead the mares and the following foals off to another field at the top end of the farm (a field with a big open barn to give the little ones some shelter) lead everyone in and lead the mares straight out. Off run the foals to explore this new area, and their mums are returned to the mixed field. The mares breathe a sigh of relief at at last being free of their charges, and I have never had a mare get more than a half bag of milk for more than a day or two.
Last year I did have one mare who whinnied at the fence for half an hour, but she was a first foaler and earlier had been a very protective Mum.
After a couple of days of setting in, we then 'handle' the weanlings. Into the barn they come, more worming, foot trimming, headcollars get put on - just part of the fun, never an objection - and gentle brushing starts. Everyone is happy!!
Of course I realise that the 'set up' I have here is perfect for the way I like to wean/treat my animals, but I used to follow the same proceedure on a much smaller acreage and it always worked for me. Not sure how I would handle it if I only had one foal tho?
Sorry for the long post - got a bit carried away! Put it down to old age LOL!!
Anna