Pregnant Mare Feeding

Feeding a pregnant mare is straightforward, but getting it wrong creates real problems—not just for her, but for the foal developing inside. A pregnant mare needs more calories than a non-pregnant horse, and she needs specific minerals that her body will pour into building a foal. The catch is that most of her pregnancy, you can't even tell she's pregnant, so it's easy to under-feed without realizing it.

The first two-thirds of pregnancy is almost boring from a feeding standpoint. Your mare doesn't look obviously pregnant, her energy needs haven't spiked dramatically, and if you're not paying attention, you might feed her exactly as you always have. That's a mistake. The foal is building bone and muscle and organs the entire time, and those need specific nutrients your hay alone probably isn't providing.

The last three months—that's when things get obvious and critical. The foal is putting on serious weight, the mare's belly is unmistakable, and her feed needs climb sharply. This is when feeding mistakes become visible. A mare who's been under-fed through pregnancy shows up looking ribby and exhausted in the final trimester. A mare who's well-fed carries pregnancy well and has the energy reserves to handle birth and lactation.

The good news is that feeding a pregnant mare isn't complicated. It's mostly about understanding when her needs change and what nutrients matter most at each stage. A well-fed pregnant mare delivers a healthy foal, recovers well from birth, and produces milk that a newborn can actually thrive on.

This guide walks through what a pregnant mare actually needs, when she needs it, and how to avoid the common mistakes that cause problems down the line.

During the first six months of pregnancy, a mare's energy needs don't increase all that much. She's carrying a foal that weighs maybe 50 pounds at six months, which is nothing compared to her own weight. Most mares can maintain pregnancy on decent pasture and hay, the same way they eat when they're not pregnant. What changes is what's inside that hay needs to be enough to build a foal.

Calcium and phosphorus are the big ones. A foal's skeleton needs massive amounts of both, and if your mare isn't getting adequate minerals, her body will start pulling calcium from her own bones to build the foal. You might not notice this immediately, but three months into lactation when her bones are weak and she's exhausted, you'll see the consequences. The ratio matters too—calcium should be higher than phosphorus. Most grass hay has reasonable calcium but often higher phosphorus relative to what a pregnant mare needs.

Protein gets more critical as pregnancy advances. In the last three months, the foal is accumulating muscle tissue at a noticeable rate. A mare on poor-quality hay alone won't have enough protein to support that growth plus maintain her own body condition. You're looking at needing maybe 12 percent protein in total diet once you're in the third trimester.

Vitamins matter, especially vitamin A and the B vitamins. Old hay loses vitamin A quickly—hay that's been sitting around for a year might have a quarter of the vitamin A it had fresh. A pregnant mare needs good vitamin A levels because the foal will be born with whatever vitamin A reserves she passes to him. A foal born with poor vitamin A stores struggles with eye health, immune function, and overall resilience.

In the final months, energy needs actually do climb noticeably. The foal is gaining rapidly, and the mare is carrying significantly more weight. She'll need maybe 20 to 30 percent more calories in the last three months than she needed in the first months of pregnancy. If you don't increase her feed at this point, she starts dropping condition visibly.

Water needs increase throughout pregnancy too. As the foal grows, it takes more water to support the increased blood volume, the amniotic fluid, and everything else. A pregnant mare should have unlimited access to water at all times. Some grain also helps drive water intake, which is another reason adding some grain to her diet later in pregnancy makes sense.

Start by looking at what your mare is eating now. If she's on decent pasture or good-quality hay, she can probably maintain the first six months of pregnancy without changes. But check her condition. She should be at a body condition score of 6 or 7—not fat, but rounded out, no ribs obviously showing, no spine sticking up. If she's already thin, she needs more feed now, not later.

Once you're into month six or seven, start adding grain if you haven't already. A pregnant mare in the final third doesn't need huge amounts of grain, but she needs some—maybe three to five pounds a day of a quality grain or grain mix, depending on her size and the hay quality. The grain should have adequate protein and minerals. A straight oat grain won't cut it; you need something formulated to support a pregnant mare or at least provide balanced nutrition.

If your mare is on poor-quality hay—stemmy, old, or low-protein—she needs grain earlier. You might start adding grain at month five or six just because the hay isn't carrying its weight nutritionally. Alfalfa hay is your friend here if your mare will eat it. Alfalfa is higher in protein and calcium than grass hay, so it does a lot of the nutritional heavy lifting on its own. If your mare is on straight grass hay, the grain and supplements become more important.

Add a vitamin and mineral supplement unless your grain already has them. A pregnant mare needs calcium, phosphorus, copper, zinc, and other minerals that might not be in your hay or grain in adequate amounts. A good equine vitamin supplement designed for mares covers these gaps. There are dozens of products out there—call your vet or grain store if you're not sure which one to use.

Change her feed gradually as you increase it. If she's been on straight hay and you suddenly dump five pounds of grain on her, her digestive system will rebel. Add a pound or so every few days until you reach the amount you want to feed. This prevents digestive upset and colic.

By the time she's two months from foaling, she should be on full feed for late pregnancy. That might look like good-quality hay, four to six pounds of grain or concentrate daily, and a supplement. Her weight should look solid but not fat. If she looks like she's gained 100 pounds and can barely move, she's too heavy, which creates foaling problems. If she looks thin and tired, she's not getting enough.

Feed her in portions rather than all at once if you can. Two or three meals a day is easier on the digestive system than one large meal, especially as her belly gets crowded with foal.

Easy keepers—the horses that hold weight on a look and a smile—sometimes get under-fed during pregnancy because their owners forget they're eating for two now. Your easy keeper mare might maintain her own body condition on minimal feed but won't build a healthy foal on the same ration. You still need to increase her nutrition during pregnancy even if she doesn't need extra calories to stay round. Pay attention to protein and minerals especially.

Hard keepers, on the other hand, struggle during pregnancy. A mare who was thin before she got pregnant will get thinner as the foal grows unless you significantly increase her feed. These mares often need grain from the beginning of pregnancy, not just the last three months. If your mare has always been hard to keep weight on, expect to feed her heavily during pregnancy and lactation. Don't let her get ribby; it's not good for her or the foal.

Young mares—first-time pregnancies—are their own problem. A three or four-year-old mare is still growing herself while trying to grow a foal. She needs extra nutrients just for her own development plus extra for the pregnancy. First pregnancies in young mares produce smaller foals sometimes because the mare's body is pulling nutrition for her own growth. Feed young mares well during their first pregnancy.

Older mares need the same nutrition as younger ones but sometimes have weaker digestive systems. If your mare is 18 or 20, she might need multiple smaller meals instead of one big feed, or she might benefit from more easily digestible feed like pelleted concentrates instead of whole grain. Talk to your vet if you have concerns about her age and ability to handle pregnancy.

Mares prone to developmental orthopedic disease in their foals need special attention to trace minerals during pregnancy. Foals inherit some vulnerability from their mothers' nutrition during pregnancy. If your breeding line has produced foals with joint problems, make sure the pregnant mare is getting excellent mineral nutrition, especially copper and zinc. This is worth consulting your vet about if you have a history of problems.

Under-feeding in early pregnancy seems harmless—the foal is small, the mare still looks normal, nothing seems to be going wrong. But a foal's skeletal development starts immediately, and poor mineral nutrition in early pregnancy sets up problems that show up later. A foal born from a poorly nourished mare might have weak bones, joint problems, or poor immune function. Some of these problems don't show until the foal is being ridden or trained.

Over-feeding in late pregnancy creates different problems. A mare who's fat at foaling has a harder delivery, higher risk of complications, and less appetite to eat colostrum and milk after birth. Fat mares also struggle more with diseases like laminitis and EPM. You want your mare in good condition, not obese.

Mares on poor-quality hay who don't get supplemental feeding or grain often develop pregnancy-related complications. Low body condition going into the final trimester means the mare enters lactation in poor shape, which tanks her milk production. A foal whose dam doesn't produce enough milk is weak, doesn't get the colostrum he needs for immune protection, and grows poorly. The problems cascade.

Edema—swelling in the legs and belly—is common in late pregnancy and usually harmless, but it's a sign the mare's body is under stress. Excessive swelling might indicate nutritional deficiencies or other problems worth discussing with your vet. Some swelling is normal; dramatic puffiness isn't.

Colic during pregnancy is more dangerous than colic in a non-pregnant mare because you have two beings to worry about. Feed changes, sudden dietary shifts, or impaction colic can happen. This is why gradual changes and plenty of water matter. If your pregnant mare colics, call your vet immediately.

Laminitis before foaling is rare but happens, especially in mares who are overweight or have metabolic issues. Watch for lameness or pain in the feet, especially in the weeks before foaling. If you see signs of laminitis, that's a vet emergency.

Ascites—fluid accumulation in the abdomen—can develop in late pregnancy, particularly in mares carrying twins or very large foals. This is rare and serious. Talk to your vet if your mare's belly looks abnormally swollen or hard.

Monitor your mare's body condition throughout pregnancy, not just at foaling. A simple body condition score of 1 to 9 lets you track whether she's maintaining weight well. Score her every two or three weeks. If she's getting thinner, increase her feed. If she's getting fat, dial it back. Body condition should stay steady or increase slightly but not dramatically.

Weigh your mare if you can at the beginning of pregnancy. Some barns have scales; some vets can weigh horses. Knowing her baseline weight helps you judge whether she's gaining appropriately. A 1200-pound mare might gain 100 to 150 pounds by foaling, but a lot of that is foal and fluids, not permanent weight gain on the mare herself.

Timing grain additions matters practically. Most people add grain in month six or seven, but read your mare's body. If she's thin or on poor hay, start earlier. If she's an easy keeper on excellent pasture, you might not need grain until month eight. Let her body tell you what she needs.

If you're not sure whether your hay is good quality, get it tested. Most agricultural extension offices can do hay analysis, or you can send samples to a private lab. A hay test tells you the protein, calcium, phosphorus, and other nutrients so you know what you're actually feeding. This is cheap insurance, especially with a pregnant mare.

Water is easy to overlook but critical. Cold water in winter might be less appealing, which drives down her water intake. Keep water warm or at least not ice cold. Some people add a small amount of salt to the grain to increase thirst and water intake, which is fine as long as she has plenty of water to drink.

Have your vet do a pregnancy check at month five or six if possible. This confirms she's pregnant, rules out twins (which are an obstetric nightmare), and gives you baseline information. It's also the time to discuss any feeding concerns with your vet specifically based on her condition.

Don't suddenly stop feeding grain after she foals. The same mare that needed extra nutrition for pregnancy now needs extra nutrition for milk production. Her feed should stay high after birth, then gradually decrease as the foal eats more grass and hay. Dropping her back to pre-pregnancy rations immediately after foaling tanks her milk production and energy reserves when she needs them most.