Caring for a Pregnant Mare: Nutrition, Supplements & Feeding Tips

Why Balanced Nutrition Is Essential for a Brood Mare

As with all horses, it is important that a broodmare is fed a balanced diet which meets all of her nutrient requirements.

It can be tempting to increase your mare’s feed as soon as you discover she is pregnant however, this is not necessary. A mare’s dietary requirements don’t really escalate until the third trimester of pregnancy. The unborn foal will grow at a slow enough rate during the first two trimesters that the mare’s nutrient requirements will be the same as a horse being fed at maintenance.

Throughout pregnancy, it is important that mares receive adequate amounts of forage equating to at least 1.5% of their body weight daily. Where possible forage should be provided on an ad lib basis.

Feeding Guidelines for Pregnant Mares: Forage & Fibre

It is not uncommon for mare’s to lose their appetite in later gestation and struggle to consume adequate amounts of forage as the growing foal compresses the digestive tract. In this case, you may want to consider offering soaked beet pulp, hay cubes or grass cubes to ensure she is still receiving sufficient dietary fibre.

High quality oils or micronised linseed can also be great for mares with a more limited appetite who are prone to drop condition as these are calorie dense and only need to be fed in small quantities. Instead of offering large bucket feeds, these can be split into smaller feeds spaced throughout the day.

Maintaining Ideal Body Condition During Mare Pregnancy

Maintaining an appropriate body condition throughout pregnancy is essential. Mares that are underweight may not provide adequate nutrients to their developing foal, leading to low birth weight and weak immunity. They’re also at risk of poor colostrum quality, lower milk production and postpartum health issues, which can affect both their recovery and future fertility.

Overweight mares and their foals are more prone to developing metabolic disorders like insulin resistance. Studies have also shown that foals born to overweight mares are at a higher risk of developing OCD, a condition that affects the cartilage and bone within the horse’s joints. Excess weight can also reduce milk production and negatively impact reproductive health in future breeding seasons.

Nutrient Requirements in the Final Trimester of Pregnancy

As a mare’s nutrient requirements increase during the third trimester, she will often require additional supplementary feeding to ensure her and her unborn foal’s nutrient requirements are being met. Some of the most important nutrients to consider include:

Best Feed for Pregnant Mares: Energy-Rich Options

During the final trimester, the foal experiences the most rapid growth, to facilitate this and milk production, a mare’s energy intake will need to be increased. The National Research Council (NRC) indicates that maintenance requirements for digestible energy (DE) increase by approximately 20% during the eleventh month of gestation. At this stage, it is a good idea to supplement high quality forage with energy dense feeds to ensure adequate calories are being supplied.

Protein for Brood Mares: Supporting Foetal Growth

Protein is one of the most important nutrients in later pregnancy as it plays an essential role in the development of body tissues. Most stud mixes and feed formulated for pregnant mares will have a high protein content. Alfalfa, certain grass pellets, linseed and pea powder are other great ways to increase the protein content of the diet.

Calcium & Phosphorus: Bone Health for the Unborn Foal

Calcium and phosphorus requirements will increase in the third trimester to support foetal bone development. These nutrients should be fed at a ratio of 2:1. Insufficient calcium or imbalanced ratios can affect foal bone health and later performance.

The Role of Copper & Zinc in Pregnant Mare Care

Deficiencies in copper and zinc have been linked to developmental orthopaedic diseases such as OCD in foals. Supplementing appropriately during the third trimester helps lay the foundation for strong connective tissue, cartilage development and skeletal integrity.

Antioxidants: Vitamin E & Selenium for Pregnant Mares

These act as antioxidants and are important for immune system support in both the mare and the unborn foal. Adequate levels help improve colostrum quality and the foal’s ability to fight off early infections. Mares will normally require increased amounts of Vitamin E from conception.

Why Vitamin A Matters Throughout Mare Pregnancy

Like Vitamin E, the mare’s Vitamin A requirements remain elevated throughout her whole pregnancy. Not only is Vitamin A required for reproductive health, it also plays an important role in the formation of the unborn foal’s body tissues. Fresh pasture is one of the best sources of Vitamin A. If grazing is scarce, this may need supplemented in the diet.

Making Safe Dietary Changes for a Pregnant Mare

If making changes to the diet these should always be done gradually in order to prevent digestive upset. There are many feeds available which are specifically formulated with pregnant mares in mind. Some mares can benefit from further supplementation in later pregnancy if their diet is lacking in certain nutrients. Always consult with a vet or nutritionist if concerned about nutrient deficiencies or if you are unsure which feeds are suitable for your own horse.

Best Supplements for Pregnant Mares: What to Avoid & What to Include

There are certain herbs and ingredients often found in supplements that should not be given during pregnancy as they may affect the reproductive tract. For this reason, unfortunately none of our herbal blends are suitable to be given to a mare in foal. We recommend removing herbal supplements from the diet three weeks prior to covering.

Feeding a pregnant mare is about balance—providing enough nutrients to support both her and the foal without overfeeding. With attention to her changing needs and careful monitoring, you can set the stage for a healthy foal and smooth foaling process. If you have any concerns regarding what to feed your mare always consult with your vet or a qualified nutritionist.