Hi Susan;
In the past two years we've had foals born at all times of the year. I actually don't think some of these Mini mares QUIT cycling for the winter. In 2003 our Flame was still going strong (that is STRONG--as in stronger than she had all spring or summer!) in late September...again in October...then in November...that year our 2 year old stallion wouldn't breed, and Ice Man was just a yearling...we did send her out for one cover in September, but she didn't catch. She did "seem" to quit after her November cycle, but in March she was in heat without it being obvious to us. That 2 year old that wouldn't breed got over the fence in March & did breed her that one afternoon...giving us our February '05 filly.
Here in the cold, frozen north I do not recommend Dec-Feb foals unless you have a heated barn(which we don't!). We coped & the filly (born into -30 temperatures) flourished--by day 3 the weather had turned milder & with her blanket on she was able to run & play outside, even with the deep snow. She quickly learned not to venture into the snowbanks, and on the packed snow she was fine.
Fall babies...year & a half old Ice Man bred Timie through the fence in October 2003, so we had a September 2 filly in '04. Serenade was born very slick coated, and the first week of October we did get some fairly chilly nights. There were a couple frosty mornings where she felt the cold a little bit, but she'd get running around & warmed right up. By mid October she was growing a pretty good coat & had no further problems with cool weather. Winter posed no problems at all for her, even when it went down to -35. Snow & cold caused no restrictions on her winter exercise.
We had absolutely no problem keeping the mare in good shape. Well, I should say that Timie, once she is nursing a foal, tends to lose weight no matter what time of the year she foals--she foaled a month early this year, on July 4th, and has dropped some weight right off. We had to do the same now as we did last fall--change/add to her ration, and then she holds her own. I wouldn't say that it was any more difficult to keep weight on her last fall/winter than it is now. Serenade stayed with her until spring, which made it a bit later than we usually wean, but it was just easier that way.
On the plus side, a fall foal has fewer bugs to cope with than a summer foal--that late filly last year had a much nicer season to be born into than our summer & late spring foals did this year! Flies & mosquitos & rain & mud make it quite miserable for the little ones to be outside here now.
On the negative side, selling or showing a late foal may be a little more difficult. Some people won't want to buy a late foal. Depending just when the foal is born & when you wean, you could end up needing to ship the foal to it's new home in the coldest part of winter. I've had a mature Morgan delivered by air ride semi on a bitterly cold night (9 hour trip, he arrived at midnight & it was COLD--wasn't my choice, but the ride was booked & we had this sudden blast of arctic air unseasonably early) & he did just fine, but I personally wouldn't want to ship a foal in that kind of weather. As for showing, I've had a couple Minis that would hold their own as 9 month old "foals" showing in the yearling class, but it didn't work for Serenade. She's a tall leggy B filly, and at show time in June was just 9 months old; she was very growthy and just not ready to show, especially against fillies that were true yearlings, 12-14 months old.
In '06 our latest foals should be born by the end of June, and I'll be hoping that those last mares foal early, so they have early June babies. Ideally I want them to come by mid May. If they must be later than that I'd actually rather they come in September instead of July!