Mares who were covered in the spring will be heading towards the half way point of their gestation as autumn turns to winter and the question is, once the grass stops growing and winter approaches, how do we feed to ensure optimal health and development of the foal, as well as maintaining health and condition in the mare?
A pregnant mare’s nutrient requirements increase substantially only in the last 3 months of gestation, when the developing foal (the foetus) does most of its growing. So until then you need to feed the mare no differently from a non-breeding horse in the same level of work, paying particular attention to ensuring a balanced diet with appropriate levels of vitamins and minerals. It’s not healthy to simply turn the mare out to grass and allow her to become fat because this can cause problems at delivery time. In addition, she should be on a rising plane of nutrition is she is going to be bred again, so ensuring she enters her final 3 months before foaling in slim condition is ideal.
The most important factor is the same as for every horse; monitor the mare as an individual and adjust her diet accordingly. Ensure she stays in good condition without getting too fat – which means you may have to restrict her grass intake – and ensure a balanced diet. When the grass stops growing, replace it with forage of a good hygienic quality, and of a nutrient quality appropriate to the mare’s condition. If the mare lives out, ensure she has good shelter and a dry area to stand on for part of the day. As the mare’s shape changes and her abdomen enlarges as the foal grows, you need to keep feeling for fat covering across her crest, shoulders, flanks and rump to ensure she is maintaining condition. In the final few months of gestation weightapes become less useful.
Do not make the mistake of feeding a scoop of stud mix or cubes to a mare in good condition eating plenty of forage, who doesn’t need any extra calories (energy). Doing so will add unnecessary calories and yet will not fulfill the mare’s vitamin and mineral requirements (you need to feed the full recommended amount to balance the diet for micronutrients). Instead, balance her diet with a multi-vitamin and mineral supplement or balancer, ideally formulated specifically for broodmares. Offer a salt block in her field or stable.
During the final 3 months of gestation, the mare’s nutrient requirements increase significantly and her intake of essential vitamins and minerals during this time is crucial for the health of the developing foal. The foetus must lay down stores of minerals for use after birth, since mare’s milk does not supply enough minerals. The mare’s appetite may decrease a little and the ideal feed is good grass, supplemented with a good quality stud compound feed (if she requires the full amount), a pelleted balancer (if not) or a multi-vitamin and mineral supplement if her body condition is good and she is getting enough calories from forage.
Research has shown that feeding extra vitamin E and selenium during the final 3 months of pregnancy boosts the transfer of immunity from mare to foal, and ideally total dietary levels should be about 2000 mg of vitamin E and 3 mg selenium for a 500 kg mare.