Pregnant and Lactating Mare Nutrition: Feeding for Mare and Foal Health

Pregnant and lactating mares have changing nutrition needs, and the biggest increases do not happen evenly across the whole pregnancy. In most mares, nutrient demand stays fairly close to maintenance through early and mid-gestation, then climbs during the last trimester as fetal growth accelerates. After foaling, needs increase even more because milk production requires large amounts of energy, protein, calcium, and phosphorus.

For many mares, the foundation is still high-quality forage. Good pasture or hay can meet a large share of daily needs, but forage alone may fall short in late gestation or early lactation, especially for calories, lysine, calcium, phosphorus, copper, and zinc. That is why many broodmares benefit from a properly fortified broodmare concentrate or a ration balancer added to forage, rather than unfortified grain mixes or multiple separate supplements.

A practical goal is to keep the mare in a body condition score of about 5 to 6 out of 9. Mares that are too thin may struggle to maintain milk production and may have a harder time rebreeding. Mares that are overconditioned can face their own problems, including metabolic stress and foaling complications. Regular weight tape checks, body condition scoring, and ration review with your vet are more useful than guessing by eye.

Water and salt also matter. Lactating mares can drink dramatically more than dry mares, and even mild dehydration can affect feed intake and milk production. Fresh water, free-choice salt, gradual feed changes, and forage testing are some of the most helpful steps a pet parent can take to support both mare and foal health.

There is no one safe amount that fits every mare. The right ration depends on body weight, forage quality, pasture access, age, breed type, body condition, milk production, and whether the mare is carrying one foal or has other health concerns. As a starting point, most mares should eat about 1.5% to 2.5% of body weight per day as total feed on a dry matter basis, with forage making up the bulk of the ration unless your vet recommends otherwise.

For a 500-kg (1,100-lb) mare, reference requirements help show how much needs can change. Maintenance is about 16.7 Mcal/day, 630 g crude protein, 20 g calcium, and 14 g phosphorus. In the first month of lactation, that same mare may need about 31.7 Mcal/day, 1,535 g crude protein, 59.1 g calcium, and 38.3 g phosphorus. Late-gestation needs rise too, though usually not as sharply as early lactation. Because appetite may drop in the last 1 to 2 months of pregnancy as abdominal space becomes limited, some mares need a more nutrient-dense ration fed in smaller meals.

In real-world feeding, that often means free-choice or generous high-quality hay or pasture, plus a broodmare feed or ration balancer fed according to label directions and adjusted to body condition. Avoid making large jumps in grain or concentrate. Increase feed gradually over 7 to 10 days, divide concentrates into multiple meals, and ask your vet whether your hay analysis supports the calcium, phosphorus, copper, zinc, and selenium balance your mare needs.

If your mare is overweight, insulin-dysregulated, a pony type, or has poor teeth, ulcers, or limited forage intake, the safest amount may look very different. Your vet can help tailor the ration so the mare gets enough nutrition without overfeeding calories or starch.

Nutrition problems in pregnant and lactating mares are often subtle at first. Common warning signs include weight loss, dropping body condition, poor topline, dull hair coat, reduced appetite, poor milk production, pica such as eating dirt or wood, and a foal that seems hungry, slow-growing, or frequently trying to nurse. Loose manure, recurrent mild colic, and feed refusal can also point to a ration that is not working well.

Mineral imbalance can be harder to spot without testing. Diets heavy in unfortified grain and low in calcium may increase the risk of skeletal and metabolic problems. Poor-quality forage or an unbalanced homemade ration may also leave mares short on protein quality, copper, zinc, or key vitamins. In some cases, the first clue is not the mare at all, but a foal with poor growth, weak nursing behavior, or developmental concerns.

See your vet immediately if a pregnant or newly foaled mare has colic signs, marked depression, fever, sudden feed refusal, diarrhea, severe weakness, reduced water intake, udder abnormalities, premature lactation, or rapid weight loss. Also call promptly if the foal is not nursing well, seems weak, or the mare appears to have little milk. Those problems are not always caused by nutrition, but nutrition can be part of the picture and delays can put both mare and foal at risk.

If you are unsure whether the ration is the issue, ask your vet about a body condition exam, hay analysis, dental check, fecal parasite plan, and a full ration review. Those steps often identify problems faster than adding supplements at random.

If your mare is not thriving on her current diet, safer alternatives usually focus on balancing the whole ration, not adding one trendy supplement. Good options include tested grass hay or mixed hay, alfalfa in appropriate amounts when extra protein and calcium are helpful, a commercial broodmare feed, or a ration balancer if calories are adequate but vitamins and minerals are lacking. For mares that need more calories without a large starch load, your vet may suggest a higher-fat feed or carefully added oil.

For mares in late gestation with reduced appetite, smaller and more frequent meals can help. For mares in early lactation, improving forage quality is often one of the most effective changes. If pasture is poor or hay quality is inconsistent, a fortified concentrate may be safer than relying on plain oats, corn, or sweet feed. Unfortified cereal grains can skew the calcium-to-phosphorus balance and may leave important trace minerals short.

If cost is a concern, conservative care can still be thoughtful care. A hay test, body condition scoring, and a basic ration balancer are often more useful than buying several separate supplements. Typical monthly cost ranges are about $180-$350 for forage alone in some regions, $40-$120 for a ration balancer, and $120-$300+ for a broodmare concentrate, depending on intake and local feed markets.

The safest alternative is the one that matches your mare’s stage, body condition, forage supply, and medical history. Your vet can help you choose among conservative, standard, and more advanced feeding approaches without overcomplicating the plan.