Feeding your Pregnant Mare

Nutritional requirements can vary greatly depending on your horse’s stage of development, level of activity, and especially if they are pregnant or lactating. When considering what to feed your broodmare, there are several things you need to take into consideration. It is important to know your mare’s body condition, the nutrient content of the feed, and most importantly what stage of her pregnancy she is in. When looking for the body condition score of your mare, you need to know which locations to look in. Pay attention to the crest of the neck, behind the shoulder, ribs, withers, crease along the back, and the tailhead. These areas will be particularly large in a horse that is more overweight, or can be sunken in on a horse that is underweight.

A broodmare’s nutritional requirements begin before the mare is even bred, and can even differ depending on whether she is a maiden or mature mare. In maiden and barren mares you want to be sure you prevent obesity and regulate their body condition so it is steady for your best chances of conception. Maiden mares that are younger (2 to 3 years old) will have higher requirements of protein, calcium, phosphorous, and vitamin A. Mature mares will usually only need a maintenance diet, unless they are hard keepers. Mares that have a good body condition before breeding will have better chances of conception. They should not be losing weight but should not be obese either.

Once your mare is pregnant, consider her nutritional requirements in three stages. The first stage is the first two-thirds of her pregnancy. During this time, the fetal size does not increase significantly and your mare should still be on a maintenance diet. Her body condition should stay constant, again without losing or becoming obese. A mare that is losing weight will have a hard time re-breeding, and an obese mare will have more trouble foaling due to weak muscles and condition. If necessary, this stage of pregnancy is the best time to adjust body condition because they can increase energy stores while nutrient demands are relatively low.

The second stage of your mare’s pregnancy is the last three months. In this time, the fetus increases about one pound per day, accounting for two-thirds of fecal growth. Energy, protein, calcium, and phosphorous requirements increase. When your mare is on a maintenance diet, good hays and grasses or legumes will usually be enough. Once into her last three months, it is a good idea to consider supplementing with concentrated feed sources.

The third stage of pregnancy is lactation. This stage requires by far the most nutrients and is a time of great physiological stress. The only other time that any horse’s nutritional requirements would be as high as during lactation is if they are in very intensive training. During this time your mare has to recover from the stress of parturition, produce milk, and often re-breed. All of her nutritional requirements will increase. During lactation, a healthy mare will produce 3% of her body weight in milk per day for the first three months, then 2% of her body weight in milk per day towards the end of lactation. If her nutritional needs are not met during lactation, her body condition will be affected the most. In extreme nutrient deficiency, milk production can decrease as well. As your mare’s milk production decreases, her feed intake should be adjusted as needed. At weaning, feed intake should be gradually decreased, allowing the mare to “dry up” faster and will prevent obesity. You should allow 7-10 days for mares to adjust to intake changes.

It is important to consult your veterinarian before any nutritional changes in your mare’s diet, and your veterinarian should be actively involved in your mare’s pregnancy. You can also contact your local Cooperative Extension office with any questions.

Gibbs, Pete G., and Karen E. Davison. "Nutritional Management of Pregnant and Lactating Mares." Texas A&M University Department of Animal Science Equine Sciences Program. Web. 15 Feb. 2012. http://animalscience.tamu.edu/images/pdf/nutrition/nutriton-nutr-mgmt-pregnant-mares.pdf
"Nutrition of the Broodmare." University of Kentucky Cooperative Extension Service. Web. 15 Feb. 2012. http://www.uky.edu/Ag/AnimalSciences/pubs/asc112.pdf.

Laura Smith, NCSU Intern