Expert Guidance for Feeding Lactating Mares

Providing the right nutrition for the lactating mare is essential for the health of the foal and its mother. While most breeders intuitively recognize the need for a specialized diet, they may not realize just how crucial balanced nutrition is in helping lower the risk of developmental orthopedic disease (DOD) and ensuring a happy, healthy life for both mare and foal.

Fueling the future starts from day 1

Nutrition should be considered even before conception to help improve the odds of the mare becoming pregnant.

However, it’s during the final trimester of gestation when the nutritional needs of the mare increase significantly. Energy requirements can be demanding during lactation. This is when it’s vital to provide adequate protein, vitamins, minerals and calories to maintain a healthy body condition, which helps her produce nutritious milk and support rapid growth of the developing foal.

Protein:

Provides essential building blocks needed for fetal growth, muscle development and tissue repair. Deficiencies may present as muscle loss, especially along the topline of the mare.

Vitamins and minerals:

Support bone development, muscle strength, immune defense and metabolic balance. Deficiencies may not be apparent but can cause complications with lactation, foaling and overall health.

Calories:

Deliver energy needed to support milk production, maintain body condition and recover after foaling. Deficiencies cause a noticeable decline in weight and body condition.

“When that foal hits the ground, the energy demands of the lactating mare are as high as the absolute hardest working horse you can imagine. It's just phenomenal—they nearly double their nutrient requirements.”
– Dr. Randel Raub, Sentinel^® Director of Research and Nutrition

Balance in body condition is best

For the lactating mare, a Body Condition Score (BCS) of five or six is ideal. Too obese, and she runs the risk of developing metabolic issues, having a difficult pregnancy. Too thin, and she may develop nutrient deficiencies that can impact the foal’s immune system and development or reduce its chances of rebreeding.

“You certainly don't want them to be obese or too thin because that can reduce rebreeding efficiency,” Dr. Raub says. “And you don’t want them in a negative nutrient balance with a score of four or less because it will put them in a compromised position during lactation.”

Physical markers to look for:

Moderate fat levels:

Back level. Ribs cannot be visually distinguished but can be easily felt. Fat around tailhead beginning to feel spongy. Withers appear rounded over spinous processes. Shoulders and neck blend smoothly into body.

Moderate to Fleshy Fat Levels:

May have a slight crease down back. Fat over ribs feels spongy. Fat around tailhead feels soft. Fat beginning to be deposited along withers, behind shoulders and neck.

A healthy mare should have:

• Ribs well-covered with a thin layer of fat
• No excessive fat deposits on the neck, withers or back
• Slight fat deposits near the shoulder

Forage is always the foundation

Forage provides the nutritional basis for all horses, and it’s especially critical for broodmares because it contains essential nutrients and fiber, which keeps the gut working properly. Keep in mind, the quality of forage is just as important as the type. If your clients aren’t sure where to start, they can usually contact their local feed company, store or extension office to take a sample. This provides the foundation to develop the rest of their nutritional plan.

"If you get your hay tested, it helps you evaluate how you should be feeding a horse and if you need to supplement with a concentrate or other feed type,” Dr. Raub says. “Most folks blame a drop in their horse's weight or change in condition on the feed when it is really the quality of hay, forage or pasture that has changed.”

The building blocks of life need a solid foundation

Much like forage, providing sufficient protein is critical, but the quality of that protein plays an equally vital role. Look for the amino acid profile—the building blocks of protein—to determine how effectively these nutrients are utilized.

The first three limiting amino acids for horses are lysine, methionine and threonine, meaning horses can't produce them on their own. And, if a horse is deficient, it can't fully use protein for things like muscle development, hoof growth and maintaining its hair coat.

Here’s what to look for in mare and foal feeds:

• 14-16% Protein
• Lysine
• Methionine
• Threonine

Delivering essential nutrients

The right nutrients play critical roles in supporting milk production, bone health, muscle function and overall foal development. Ensuring the correct levels and ratios of essential vitamins and minerals minimizes the risk of developmental issues and optimizes health outcomes for both the mare and foal.

“Concerns about an orthopedic disease should be an in-utero consideration, as well as when the foal is growing,” Dr. Raub says. “Adequate nutrition to the mare during that gestational period will manifest in diminishing at least the risk of developmental orthopedic disease in the foal.”

These nutrients are essential for mares and foals:

Copper and zinc:

Vital for bone and joint health. Deficiencies may impact cartilage development and lead to developmental orthopedic disease in the foal.

Calcium and phosphorus:

Maintain a 2-to-1 calcium to phosphorus ratio to support strong bones. Deficiencies may impact foal bone health and development.

Vitamin E and selenium:

Promote muscle development and oxidative health. Deficiencies may impact foal muscle growth, development and recovery.

When to consider supplementation

If a pregnant mare is being fed recommended feed levels and still struggling to maintain body condition or has low energy levels, it may be appropriate to introduce a supplement to their diet. The same is true if the mare struggles to maintain weight during lactation. Increasing grain ration is the first step, but if that’s not enough you may consider a ration balancer or a high-fat supplement. A good ration balancer fills nutritional gaps without excess calories, making it ideal for pregnant mares that need a precise, balanced diet.

Here’s what to look for in a quality supplement:

Quality protein:

Supports muscle growth and development, as well as tissue maintenance, hoof and coat quality, immune function and overall health.

Essential vitamins:

Provide key nutrients such as calcium, phosphorus, selenium and zinc to guard against deficiencies and maintain optimal health and metabolism.

Trace mineral amino acid complexes:

Maintaining optimum levels and ratios of bio-available trace amino acid complexes like lysine and methionine are crucial for proper absorption to support muscle and coat health.

“Oftentimes the forage may not have the full spectrum of vitamins and minerals that you want to deliver. A concentrated supplement can fill in a lot of the gaps that the forage component may not be able to provide.” – Dr. Randel Raub

Get expert help in nourishing new life

Lactating mares have unique and demanding nutritional needs that require careful attention and planning. Every aspect of their diet plays a vital role in supporting both the mare’s recovery and the foal’s development. By prioritizing these critical nutrients and consulting with nutritionists when needed, you can ensure a strong foundation for the health and well-being of your patients.