Before exploring dietary options, take inventory of your broodmare. What breed or type is she—a fine-boned Arabian; a rugged, sporty half-Thoroughbred; or a muscly stock-type? Where would she place on the metabolism spectrum: is she an easy keeper, a hard keeper, or average in her conversion of calories to body maintenance and fat stores? What does she weigh when she’s in moderate body condition?

“Horses will generally consume 1.5-3.0% of their body weight in dry matter intake daily, with lactating mares at the upper end of this range,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research. “Forages would supply at least half of this dry matter but may provide considerably more depending on the mare’s phenotype and metabolism.” Identifying proper forage for broodmares is therefore paramount.

Hay Inventory:

As with all hays intended for horses, broodmares should be offered high-quality hay that is free of any dust, mold, or weeds. The texture of the hay should be soft, and the smell pleasant and appealing. Not only is high-quality hay more palatable, but it can provide significantly more calories than lower quality hay. Toss any hay that is refused or soiled.

The type of hay given—whether it is a grass or legume—depends largely on the mare and availability. Early and mid-bloom alfalfa, for example, provide more energy than many good-quality grass hays, even those harvested in early maturity.

“With this in mind, alfalfa hay or an alfalfa-blend hay may be appropriate for mares that require more energy to maintain body condition during lactation. Think of the hard keepers that put a lot of energy into milk production, like some Thoroughbred mares,” Crandell said. On the contrary, for mares that are known to be easy keepers, alfalfa may provide too many calories. A grass or alfalfa-grass mix might be more appropriate for them.

Depending on the mare’s foaling date, fresh forage might be available to lactating mares. The quality and quantity of pasture may vary from farm to farm. If mares are allowed access to high-quality, properly maintained pasture for much of the day, then this will go far in meeting a mare’s energy requirements but likely will not satisfy them entirely.

Because of their high energy and nutrient needs, mares cannot generally consume sufficient forage to meet their nutritional requirements. Mares in late gestation and lactation are usually provided concentrates to fulfill this caloric shortfall.

The amount of concentrate given will depend on the mare, but the general feeding recommendations supplied by the manufacturer provide a logical starting point. If the mare requires less concentrate than the manufacturer suggests, a ration balancer pellet can offer further nutrition. A ration balancer is a concentrated source of protein, vitamins, and minerals, typically fed in small amounts, such as 1-2 lb (0.45-0.9 kg) per day.

Other considerations when managing lactating mares:

• While mares in late gestation may have a reduced appetite, lactating mares typically have normal, even ravenous, appetites. Because of this, mares should have access to appropriate forage at all times. Tall, large-framed broodmares (1,300 lb or 600 kg) may consume more than 40 lb (18 kg) of hay daily. If high-quality pasture is available as a forage source, hay may not be necessary, but many hours of grazing would be necessary for mares to consume sufficient forage. “Grass contains a great deal of water. Large quantities of pasture are needed to fulfill the forage requirement. Some researchers estimate that four acres of quality pasture is needed for every mare-foal pair,” Crandell said.
• Choose a concentrate formulated expressly to meet the nutritional needs of mares and foals. Use the manufacturer’s recommendations as a launching point, and adjust feed as necessary, staying mindful to keep meals as near to no more than 5 lb (2.3 kg) as possible. Most mares will typically consume 6-12 lb (2.7-5.5 kg) of concentrate per day. Divide into two or three meals. Because energy requirements peak in early lactation, more feed might be necessary then as opposed to mid or late lactation.
• Consider rebreeding efficiency. Keep lactating mares in moderate body condition. Maintaining mares throughout the reproductive cycle at higher body condition scores holds no advantage. In fact, maternal obesity has been linked to systemic inflammation, decreased insulin sensitivity, and an increased incidence of osteochondrosis in foals.^* Further, long-term obesity may predispose mares to endocrine-related disorders, such as insulin dysregulation, and increased risk of dystocia, according to Crandell.
• Mares that are unable to maintain moderate body condition should have their diets evaluated. If high-quality forage is provided in adequate quantities, attention should be turned to the concentrate portion of the diet. A concentrate that features various energy sources should be fed. Different energy sources include starch (as found in cereal grains), fermentable fiber (beet pulp, soy hulls), and fat (vegetable oil, stabilized rice bran). Add more calories to the diet by top-dressing fat. For example, oil or stabilized rice bran, onto concentrate meals. Fat is palatable so long as not too much is given at once. “As a concentrated source of calories, fat can be very helpful for increasing the energy intake without adding bulk to a diet that may already be maxed out in how much the mare can consume,” Crandell explained.

Resources:

In conclusion, do you have a specific question about Lactation in Mares: Nutritional Notes? Contact J & J Hay Farms today at 770-887-0440!

^*Robles, M., E. Nouveau, C. Gautier, L. Mendoza ,C. Dubois, M. Dahirel, B. Lagofun, M. Aubrière, J. Lejeune, I. Caudron, I. Guenon, C. Viguié, L. Wimel, H. Bouraima-Lelong, D. Serteyn, A. Couturier-Tarrade, and P. Chavatte-Palmer. 2018. Maternal obesity increases insulin resistance, low-grade inflammation and osteochondrosis lesions in foals and yearlings until 18 months of age. PloS One 13(1):