I NEVER bred a mare before 3 to foal at 4.I also looked at the mental maturity of the mare.No point in having an immature mare who won't take care of her baby.In 1 case the mare was 5 and she still was not a great mother-left her baby to go with other mares in the field-baby screaming and running frantically-I had to go out and get the mare and bring her back to her baby.Her response OH-- I forgot I had a baby.she was never bred again and I gave her away.IMO some mares are not meant to be mothers-just like some humans.IMO if you are breeding to keep a baby for yourself go for it.Just be warned it is not easy.Major stress if you are attached to your mare.Some people luck out and have no problems.I had my share and some other people's bad luck too.
I think it depends on the mare. If she is mature enough and in good physical shape, then covering at three to foal at four would be okay. Keep in mind however that once you breed a mare her body changes and some have a harder time than others getting back into show ring or work condition shape. At the age of three many of my mares are getting shown or put into training first to evaluate their readiness for breeding for one thing and to make an attempt at a show career for another. In my opinion, there should be no such thing as "just a broodmare" she should have had a show career that made her worth breeding and producing or she should be in work being used for something. ..not just popping out kids. I feel so strongly about this because I see so many "pony mills" that keep breeding and selling with no higher purpose desired for the mares except producing more. They're not cows, who need to calve to produce milk which in turn pays the bills. Many breeders will agree that four is an ok age to foal out, and I agree that physically she will probably be fine. Its a fine line between her being too young or too old for a maiden foaling as I have seen nares as young as 8 have difficulties with rheir first. I have also heard that it is better to breed mares back to back for a few years and quit rather than breed then rest and then repeat. Personally, I think every mare is different. If you are just looking to breed a foal for yourself then it may be worth a try (keep in mind the possibility of risks to your mare and even losing her to complications) as raising a foal is a very rewarding experience; but if you are looking to breed to sell offspring, I would wait a bit. Only because of where the horse market is right now. At age three, she is still young enough to do well at shows, maybe earn some points and make a name for herself, then breed her as breeding means taking a break from showing. I just hate to see baby mares start having babies themselves before having a life of their own. Long answer to a short question I know (sorry) just something to consider.
I always bred the Arabs at two to foal at three. I never did have a mare have any problem working out exactly what she had had, and I think that is only first foal syndrome anyway. I prefer to breed at three now, to foal at four, and, again, have never had any problems with this in the Minis, either. The thing you must bear in mind though is that Minis definitely have more foaling problems that Biggies, and you cannot get away form this fact. Leaving them later makes no difference to this, either, as the pelvic girdle bones become less "elastic" after time and have more problem passing a foal through. Every foal is a risk, no matter what age the mare. I will not breed form a mare under 30" and, even at 32" I will look at her carefully before breeding her. I think, honestly, that height and conformation are as important as age.
I've had mares breed at 2 to deliver at 3 without a problem. But I prefer to breed at 3 to deliver at 4. And I have bred many mares that are 28-30" tall with no problems -- some just "pop" them out! That said, with minis, you are looking for a strong hip with some depth and room for carrying a foal and delivering. The choice of stallion is important as well. I wouldn't suggest breeding one of the "sleek" girls to a heavy-boned stallion.....I think you are just looking for trouble with this kind of mix. Also, the height difference between the mare and stallion is a consideration as well.
Minis can have many problems......I say "can" because most produce just fine. But you have to be willing to really spend the time in the last month or so watching and waiting diligently for signs of delivery to be there in case something goes wrong. Plenty of good brood mares have produced year after year with no problems, and then one year everything goes wrong. So, make sure you're going to be there in case you are really needed.
And if you decide to breed, I hope you will join us on the mare/foal forum here on LB. We just love watching and waiting for these little ones to arrive.