mare in foal

Question
How do I know what the ideal weight is through out my mares pregnancy?  she is now in her 7th month and has steadily gained about 100 lbs she is about a 1050 lbs mare when not in foal.  I just don't want to feed her to much or have her get to heavy.  this is a mare that has had colic surgery so I don't want to much weight on that scare tissue.  i stopped ridding her in her 6th month but she is lunged everyday for about 15 to 20 min with 2 Days a week off.  I am feeding a eastern Oregon mix of alfalfa and orchard with vitamins and equine senior as advised by my vet and plan to put her on mare and foal at 9 months.  she is currently 1118 in weight.  and has a great top line. with plenty of muscle.  but what is the average or normal for a mare this size.  Not wanting her to get to fat.  thanks for all your help
sandy

Answer
Dear Sandy,
What you haven't said is how tall your mare is or the breed / size of the stallion to whom she was bred- these factors will influence the size of the foal and the actual weight gain of your mare. Frankly, I would be less concerned about actual pounds than what you see standing before you in the stall. Generally, your mare should retain her body type and form except in the barrel which, of course will expand as the fetus matures. Watch for excess fat deposits at the tail head or crestiness in the neck, thickness in the throat. I'm not a big fan of alfalfa in pregnancy but if you're feeding it under your vet's advice, so be it.
Do make sure she's had all of the appropriate vaccinations and appropriate worming. I would personally have been very wary about breeding a mare that had undergone colic surgery but I can only assume that you bred her after consultation with your equine vet. Certainly this is not ground breaking but it does warrant additional concern and you are wise to be cautious.
I did find one statistic that might be of help: A UVM (University of Vermont) website article on gestational mare nutrition professes that mares should gain .03-,08 lb per day during the last three months of gestation.
S. Evans