A pregnant 10 year old 540 kg Irish Sports Horse mare is doing well out at pasture 24/7. Depending on the weather, the mare may be stabled overnight in winter or may be able to stay out. She has put on weight since coming out of work (she was ridden in a variety of riding club activities) in the spring, and her foal is due in late March. She is currently not fed anything at all.
The macro-nutrient requirements of a pregnant mare of any breed do not rise significantly until the final 3 months of gestation, so there is no benefit from feeding extra above maintenance before this time. The mare should be kept in good condition but ideally not allowed to become overweight. Micronutrient requirements, however, rise before then. All UK pasture grass is short of some minerals so the mare needs to be fed a multi-vitamin and mineral supplement now. This can be mixed into a little low calorie chaff or unmolassed sugar beet. She should also have access to a salt block.
Good quality forage should be sourced for stabling and/or when grass runs out, and fed daily so that her gut is adapted to it if she were to come in suddenly. If the mare maintains her condition (body fat levels) throughout the winter then a stud compound feed is not necessary and instead, a good quality vitamin and mineral supplement should continue to be fed. During the final 3 months (starting in early January), a vitamin E and selenium supplement should be fed as well, which will help passive transfer of immunity to the foal.
If the mare loses condition over winter, a good quality stud compound (ideally with starch level of less than 20%) should be fed to maintain a healthy condition, and the vitamin and mineral supplement adjusted accordingly (depending on the amount of compound feed required).
The foal does most of its developing in the final 3 months and relies on a good supply of minerals from the mare to build a strong and healthy body. Feeding less than the full recommended amount of a compound feed e.g. stud mix will not meet the mineral requirements of the mare and the foal’s development will suffer.