Lactating Mare Feeding

A lactating mare is essentially running at a metabolic sprints—producing milk for a growing foal while recovering from pregnancy and managing her own body's demands. This is hands-down the most nutritionally demanding phase of a mare's life cycle. Getting feeding right during lactation matters enormously because the mare's nutrition directly impacts milk quality and quantity, which directly impacts the foal's growth and health. A well-fed lactating mare produces rich, abundant milk. An underfed mare produces less milk and milk with lower nutrient density, which slows the foal's growth and increases his susceptibility to illness.

The lactation peak usually occurs around 5-6 weeks after foaling, when milk production reaches maximum and the mare's nutritional demands are highest. From there, milk production gradually declines as the foal spends more time grazing and eating solids rather than nursing. By four to five months of age, most foals are deriving significant nutrition from pasture and feed, reducing their dependence on the mare's milk. However, the mare's total energy demands remain elevated through the entire nursing period because she's supporting growth in a rapidly developing foal.

Most mares maintain body condition reasonably well on good pasture and adequate supplementation during lactation, but some mares are hard keepers who lose weight dramatically while nursing. These mares struggle to eat enough to maintain condition while supporting milk production. Others are easier keepers and maintain weight readily. Your mare falls somewhere on this spectrum, and her individual needs determine exactly how much supplementation she requires beyond her base hay and pasture diet.

Many people underestimate how much extra a lactating mare needs, thinking pasture alone will handle it. Depending on pasture quality, this sometimes works in spring and early summer when grass is growing rapidly. By mid-summer, pasture quality drops and growth slows, making supplementation essential. By fall and especially by winter, adequate supplementation becomes crucial. A lactating mare on poor-quality hay needs significant grain supplementation to maintain condition and support milk production.

Understanding lactating mare nutrition means understanding that you're now feeding two horses—the mare and the nursing foal via the mare's milk. The foal's growth and development depend on milk quality and quantity. The mare's health and longevity depend on getting adequate nutrition herself. Balance is essential. You can't starve the mare trying to stretch feed dollars. You also don't need to overfeed her dramatically. You need to feed her appropriately for lactation.

Lactating mares need significantly more energy than non-lactating mares because milk production is metabolically expensive. Milk is made from glucose, protein, and fat drawn from the mare's bloodstream. The more milk she produces, the more energy she must consume to support that production. Early lactation requires 20-30% more calories than a non-lactating mare of the same body weight. At peak lactation (weeks 5-6 after foaling), some mares need 50% additional calories beyond their maintenance requirement. This gradually decreases as lactation tapers, but the increase remains substantial through four to six months of nursing.

Protein requirements increase dramatically during lactation because milk is protein-rich and the mare's body is actively building milk proteins from dietary protein. A lactating mare needs 12-14% crude protein in her diet, compared to 8-10% for a non-lactating mare. The type of protein matters—mare's milk is high-quality protein with excellent amino acid profiles, so the dietary protein must provide the building blocks the mare's body needs to create that milk. Higher quality hay and appropriate grain supplementation ensure adequate protein.

Calcium and phosphorus become critical during lactation because milk is rich in both minerals, and the mare's body draws these from her own mineral stores if dietary intake is inadequate. A lactating mare needs about twice the calcium and phosphorus of a non-lactating mare. More importantly, the calcium-to-phosphorus ratio matters significantly. Mare's milk is calcium-rich, so dietary calcium must exceed dietary phosphorus to support adequate milk composition. Feeding legume hay like alfalfa helps with calcium. Adding mineral supplements ensures proper calcium-phosphorus balance and adequate phosphorus.

Vitamins A and E are especially important during lactation because mare's milk contains significant quantities of both, and the mare's dietary intake must support milk content. Vitamin A becomes critical—deficiency affects milk quality and the foal's immunity. Vitamin E serves important antioxidant roles in milk. If your mare is on good-quality hay, especially legume hay, vitamin A status is usually adequate. Winter hay of poor quality may require supplemental vitamin A. Vitamin E supplementation is often recommended during lactation.

Fat becomes an important calorie source during lactation because it's calorie-dense and supports energy needs without requiring large feed volumes. Adding vegetable oil or fat supplements helps mares meet calorie requirements without feeding excessive grain, which can cause digestive issues. Mare's milk contains more fat than many people realize, and dietary fat supports adequate milk fat content. Oil supplementation is common and practical during peak lactation.

Minerals including magnesium, zinc, and copper support various aspects of milk production and immunity. A quality vitamin-mineral supplement tailored to lactating horses ensures these trace minerals are adequate. Water intake becomes especially important because milk is primarily water, and the mare must drink enough to support milk production. A lactating mare drinks more than a non-lactating mare and requires constant access to clean water.

Start with the highest quality hay you can provide. Legume hay like alfalfa is excellent for lactating mares because it's higher in protein, calcium, and generally in nutrients compared to grass hay. If you're feeding grass hay, supplement with additional protein and mineral sources. A lactating mare should have access to unlimited hay—don't restrict hay intake. She'll eat more than usual because she needs more calories, and unlimited hay supports this.

Add grain or concentrate supplementation based on your mare's body condition and pasture quality. Early in lactation when pasture is fresh and growing, some mares maintain condition on hay plus modest grain supplementation. By peak lactation or as pasture declines, grain supplementation increases significantly. A typical lactating mare might eat 1.5-2% of body weight in hay plus 1-1.5% body weight in grain daily, though individual needs vary widely. Monitor your mare's weight and adjust feeding accordingly.

Select grain mixes designed for lactating mares if available, or choose grains and supplements that support lactation. Good options include oats, barley, and commercial sweet feeds formulated for lactation. Avoid excessive molasses or simple sugars, which can cause digestive upset. Include vegetable oil or fat supplements—start with 1/2 cup daily and gradually increase to 1-2 cups daily. Oil adds calories without volume, helping mares meet energy needs.

Feed minerals and vitamins appropriately. A good quality mineral supplement or vitamin-mineral block ensures adequate trace minerals. Specific lactation supplements are available and worth considering—these typically include vitamins A and E, additional calcium and phosphorus, and trace minerals. Ask your vet or grain store about products appropriate for your area and situation. Calcium supplementation may be needed if you're not feeding legume hay.

Change diets gradually as you increase grain supplementation during early lactation. Introduce new feeds over 10-14 days, mixing increasing amounts of the new feed with decreasing amounts of the old. Abrupt changes cause digestive upset, which reduces feed intake and can decrease milk production. Mares nursing foals shouldn't experience digestive problems that reduce their overall food intake. Feed multiple times daily—three to four feedings spread throughout the day helps the mare maintain consistent milk production and steady energy levels.

Hard keeper mares during lactation often lose weight dramatically despite adequate feeding because they're predisposed to losing condition. These mares need aggressive supplementation—good quality hay unlimited, significant grain or concentrate supplementation, and possibly additional fat or calorie supplements. Monitor them closely because weight loss reduces milk production and foal growth. Talk to your vet about whether additional supplements like rice bran or additional calories are needed. Hard keepers nursing foals sometimes need 50% more grain than their non-nursing counterparts.

Easy keeper mares rarely struggle with lactation feeding because they maintain condition readily. These mares may need less grain than hard keepers while still producing adequate milk. Monitor weight to ensure they don't become overweight, which can cause metabolic issues and reduce fertility when it comes time to breed again. Easy keepers still need adequate nutrition, but you won't need to feed as aggressively as you would a hard keeper.

Young mares nursing their first foal sometimes struggle with the combined demands of still growing themselves while producing milk. A young mare is still building bone density and muscle, and lactation adds another layer of demands. These mares often need more aggressive supplementation than more mature mares. Ensure excellent nutrition for young lactating mares to support both their ongoing growth and foal feeding.

Older mares may have teeth issues or digestive efficiency that affects their ability to process feed effectively. Senior lactating mares often benefit from softer hay like hay pellets or soaked hay, and sometimes from finely textured grain that's easier to chew and digest. Older mares tend to be harder keepers during lactation and need careful monitoring to maintain condition while nursing.

Mares with metabolic issues or Cushing's disease face special challenges during lactation. The metabolic stress of lactation can exacerbate these conditions. Work closely with your vet about appropriate supplementation and management. Some mares with these conditions do well during lactation with careful feeding. Others need additional support or medication to maintain health while nursing.

Weight loss during lactation is common, especially in hard keeper mares, but excessive weight loss indicates insufficient feeding. A mare might lose some condition during peak lactation—this is normal—but she shouldn't become thin or lose weight dramatically. If your mare is losing weight despite what you consider adequate feeding, increase grain supplementation. Weight loss reduces milk production, which slows foal growth. Work with your vet if a mare continues losing weight despite increased feeding.

Decreased milk production shows up as a foal who isn't growing well, is less energetic, or shows signs of inadequate nutrition. Foal growth should be vigorous—a healthy foal gains 1.5-2.5 pounds daily during peak growth phases. If your foal isn't growing, suspect inadequate milk production, which indicates the mare needs more nutrition. Increase the mare's feed and monitor foal growth closely. Call your vet if foal growth doesn't improve.

Mastitis—inflammation or infection of the udder—is painful and affects milk production. Signs include swelling, heat, pain, or discharge from the udder, or the mare acting lethargic or painful. Mastitis requires immediate veterinary attention. Prevention includes ensuring the mare's nutrition is adequate and the nursing foal is nursing regularly. Adequate nutrition and general health reduce mastitis risk.

Retained placenta or other complications immediately after foaling can delay the onset of lactation or reduce milk production. Most mares recover and lactate normally with time and appropriate veterinary care. Feeding appropriate nutrition supports healing and lactation once the mare has recovered from foaling complications.

Digestive upset from feeding changes or excessive grain reduces overall food intake, which decreases energy availability and milk production. Make dietary changes gradually and monitor for signs of colic or diarrhea. If digestive issues develop, contact your vet and adjust the feeding plan. A mare with digestive upset won't eat enough to support lactation, so preventing digestive problems is essential.

Monitor your mare's body condition weekly and your foal's growth monthly. Weigh tape the mare monthly or assess condition score every two weeks. Measure or weigh the foal monthly to track growth. These monitoring routines let you catch problems early. If the mare is losing too much weight or the foal is growing slowly, you can adjust feeding before problems develop.

Build relationships with your vet and grain store. These are the people who understand lactating mare nutrition and local feed options. Ask them for product recommendations, advice on supplementation, and help troubleshooting feeding problems. A good grain store manager can suggest products that support lactation and help you find things when regular products are out of stock. Your vet can monitor the mare's and foal's health and recommend nutritional changes if problems develop.

Predict your mare's needs before they become urgent. In spring, plan for peak lactation demands. Source good quality hay before winter if you'll be nursing through cold months. Arrange grain delivery and ensure you have supplements on hand before you need them. Planning prevents scrambling and ensures your mare and foal get consistent, appropriate nutrition throughout the nursing period.

Keep records of what you're feeding and how the mare and foal are doing. Note weight tape readings, body condition assessments, foal growth observations, and any issues. These records help you and your vet identify patterns and make informed decisions about feeding adjustments. Over time, records from multiple lactating cycles help you understand your individual mare's needs.

Remember that this intensive nutrition period is temporary. Peak lactation demands last a few months. The mare will return to normal requirements once the foal weans. Investing in excellent nutrition during this brief window pays dividends in foal growth, mare health, and overall success. Once weaning happens, feeding requirements normalize and concerns ease considerably.