mare and foal

It should come as no surprise that a healthy mare has a better chance of maintaining condition throughout her pregnancy, avoiding complications, and producing a healthy foal.

Pregnancy is a time of change. Day by day, the growing fetus will quietly pull nutrients away from your mare’s blood, muscles and bones at an ever increasing rate, taking a toll on her body. So it makes good sense for your mare to start out healthy before breeding, and to stay healthy throughout her pregnancy so she’ll come through it in good condition.

When not to breed

If your mare wasn’t in the best of health during a previous pregnancy, give her a break before breeding her again. Use this time to boost her nutrient reserves, test her blood for deficiencies, and give her plenty of turnout and exercise.

An older broodmare may start to exhibit signs of aging – poor teeth, creaky joints and inefficient digestion. Before she is bred, get her teeth floated, make sure she has vitamin C added to her diet to build joint tissue (vitamin C synthesis declines with age), and give her a daily prebiotic to promote microbial health in the hindgut.

Don’t breed any mare that is suffering from chronic laminitis or has equine Cushing’s disease. If she has a cresty neck or fat deposits along her back and rump, she is insulin resistant and should not be bred while in this state. Having her blood tested before she becomes pregnant is also a wise decision, to rule out any unapparent health problems.

Preparation for breeding

Before being bred, your mare’s body condition should be on the fleshy side. Breeding her at the right weight will increase the likelihood of her having a smooth pregnancy and a healthy foal. And she’ll have enough reserves for lactation, which is far more demanding on her body than pregnancy.

If she is too thin, help her reach a good weight. It will be virtually impossible to help her gain weight while she’s in foal, especially during the last third of her pregnancy when her energy needs are very high.

If she is too heavy, help her lose weight by reducing or even eliminating her grain or other concentrated feed. You can provide a small carrier meal for supplements, but her energy needs can easily be met by grazing on pasture and/or hay. But do not ever restrict her forage intake. This can actually prevent her from losing weight by slowing down her metabolic rate as well as the hormonal response created by the stress of an empty stomach.

Exercise your mare. Stay within her comfort level; if she hasn’t been worked in a while, build up slowly. This will get her muscles in good shape for a healthy delivery and help her burn energy if she has too much weight on her bones.

Vaccinate and deworm

To help prevent diseases in your mare, and protect the nursing foal against microorganisms that can appear in the milk, it is important to have your pregnant mare vaccinated. Your veterinarian is your best resource regarding the standard protocols for vaccinations.

Dewormers should not be used during the first two months of pregnancy, or the last few weeks before foaling. However, every two to three months throughout the remaining gestational period, have your mare’s manure tested for worm larvae and deworm accordingly to prevent roundworm (ascarid) larvae from being transmitted to the foal.

Feeding once pregnant

Throughout her pregnancy, your mare should be fed a nutritious, balanced diet that is forage-based, contains high-quality protein, and includes appropriate supplementation to fill in any vitamin/ mineral gaps. For the first eight months, in fact, her diet will look pretty similar to her pre-pregnancy program. In the last three months, this will change – we’ll get to that later.

Even if your mare is on pasture most of the day, but especially if she is getting only hay, you’ll want to make sure all the nutritional gaps are met by using a product designed for pregnant mares. The main reason for a supplement, even at this early stage, is so your mare will have enough nutrients for fetal growth while keeping her own tissues healthy.

The first eight months

What comprises a nutritious, balanced diet during the first eight months of pregnancy? It’s easy – there are just a few basic ingredients:

• Fresh pasture and/or good quality grass hay – all she wants, offered free-choice.
• Alfalfa to complement the protein found in grass – approximately 1/3 of her total hay ration (never exceed 50% of the total hay ration).
• Vitamin E and selenium – 2 to 3 IUs of vitamin E per 2.2 lbs (1 kg) of body weight; do not exceed 3 mg/day of selenium.
• Comprehensive vitamin/mineral supplement. • Flaxseed meal, if not on lush pasture – 180 grams per 1,100 lbs (500 kg) of body weight. Or flaxseed oil – 60 ml per 1,100 lbs of body weight. • Salt – 30 grams per day of plain white salt for maintenance.
• Commercial feed if extra calories are needed to maintain weight.

The last three months – now what?

During this time, your mare requires more energy and protein, and specific minerals need to be balanced, not only for the unborn foal who will double in size during this time, but also to prepare for milk production.

• Energy: Your mare will gain 1 lb (0.5 kg) per day during this period. She needs all the forage (hay and/or pasture) she wants. Never let her stand without something to graze on – she can develop an ulcer, and the stress can potentially cause colic or laminitis. She’ll also require a commercial feed, or cereal grains and supplementation, along with additional fatty feeds such as flaxseed meal or rice bran.

• Protein: Protein sources should be balanced to provide all the amino acids your mare needs to synthesize body tissues. She requires more than just grass forage, though forage should still be the basis of her diet. Mix grasses with alfalfa to make certain her protein quality is high. A 60/40 mixture of grass/alfalfa is appropriate during this period.

I recommend adding 2.2 lbs (1 kg) of a 30% protein supplement for a 1,110 lb (500 kg) mare. To ensure complementary amino acids, look for ingredients such as soybean meal, alfalfa meal, beet pulp, rice bran and other legumes.

Lysine: This is an essential amino acid, and the building block of protein. Most commercial feeds contain at least 0.6%. But during the last three months of pregnancy, lysine requirements increase by 50%, to approximately 40 grams each day. Grasses have roughly 0.5% lysine; legumes have approximately 0.9% lysine. Once you calculate the total lysine content in your forage and feed, you can correct any shortfall by using a lysine supplement.

• Minerals: Your mare needs at least twice the amount of calcium as phosphorus and magnesium. The best way to do this is to feed grass hay plus alfalfa, and rely on your broodmare vitamin/mineral supplement to provide additional amounts of these three minerals.

Her diet should also contain at least 50 ppm of copper to prevent the foal from developing physitis, an osteopathic disorder.

She should receive a minimum concentration of 150 ppm iron, 150 ppm zinc, and 120 ppm manganese. Your mare should also receive between 3 and 5 mg of iodine per day throughout pregnancy and lactation.

Enjoy and keep it simple

Pregnancy depletes nutrient reserves, and by the time your mare reaches her last three months of gestation, her nutritional needs will have compounded dramatically in order to support the rapidly growing life inside her. And once her foal is born, she’ll need even more nutrients to produce ample and nutritious milk. You can provide all she needs by feeding a forage-based diet along with added concentrates (especially during her last three months) and one of many suitable broodmare supplements.

Enjoy this time, and you’ll both reap the benefits of a job well done. Your mare will finish her pregnancy in great condition and give you a beautiful, healthy foal.


Dr. Juliet M. Getty earned her Master of Science degree in Animal Nutrition at the University of Florida. She completed her doctoral coursework in Animal Nutrition at the University of Georgia, and continued her studies at the University of North Texas, where she earned her PhD. Winner of several teaching awards, Dr. Getty has taught comparative nutrition studies at the University of North Texas for 20 years. At the same time, she has been working in the field, consulting privately with horse owners to customize feeding plans that address a variety of health conditions. Recently retired from academia, she now resides in Denton, Texas, where she devotes herself full-time to equine nutrition. Through her consulting company, Getty Equine Nutrition, she provides consultations locally, nationally and internationally.