Nutrition Strategies to Enhance Broodmare Rebreeding Success

Rebreeding success begins well before a broodmare returns to the breeding shed—it starts with proper nutrition. The nutrients a broodmare receives before, during, and after pregnancy directly influence her fertility, recovery, and ability to conceive again quickly.

In this article, discover how proper broodmare nutrition supports fertility, pregnancy, foaling, and rebreeding success—and how the right feeding plan can help your mares produce strong, healthy foals year after year.

Why Broodmare Nutrition Impacts Fertility

Broodmare nutrition plays a critical role in fertility by influencing body condition, hormonal balance, and embryonic health.

Imbalances in key nutrients—such as protein, vitamins, minerals, and fatty acids—can interfere with ovulation, increase the risk of early embryonic loss, and negatively affect fetal development and overall pregnancy outcomes.

Certain nutrients are also vital for overall reproductive health. Omega-3 fatty acids and antioxidants support uterine integrity and fetal growth. Conversely, feeding too many calories or feeds high in natural plant estrogens (phytoestrogens) can upset a mare’s metabolism and hormone balance, making it harder for her to get in foal.

Maintaining an optimal Body Condition Score (BCS) is essential, as both underweight and overweight mares can experience reduced fertility. Mares kept at an ideal BCS not only tend to cycle earlier in the breeding season but also maintain pregnancies more successfully and produce healthier foals.

Common Challenges That Impact Broodmare Rebreeding Success

Rebreeding success in broodmares depends on more than timing—it’s shaped by the mare’s body condition, nutrition, hormonal balance, and overall health.

Recognizing the most common challenges helps breeders fine-tune management and feeding programs for better fertility outcomes.

Body Condition and Nutrition

A mare’s diet has a direct impact on her body condition by providing the energy and nutrients she needs to maintain a healthy weight and support reproduction. Maintaining a Body Condition Score (BCS) between 6 and 7 helps promote hormonal balance and fertility, as mares in this range tend to conceive more easily, commonly require fewer breeding cycles, and achieve higher conception rates during foal heat.

Obesity in broodmares is not associated with increased rates of dystocia or decreased fertility; however, emerging evidence suggests that excess body fat can reduce insulin sensitivity, potentially affecting pregnancy health and contributing to a higher incidence of developmental orthopedic disorders in foals.

Conversely, mares with a BCS below 5 or those that lose significant weight during lactation may struggle to conceive during rebreeding and often produce less milk for their foals.

Because lactating mares nearly double their nutritional needs, a balanced diet designed for lactating mares is essential to maintain ideal body condition and promote rebreeding success.

Reproductive Health

Infections or structural issues can interfere with a broodmare's conception and embryo survival. Common causes include:

  • Uterine infections (endometritis): Inflammation or infection of the uterine lining that can prevent conception.
  • Persistent breeding-induced endometritis (PBIE): Prolonged inflammation after breeding, often seen in older mares with poor uterine clearance.
  • Bacterial or fungal contamination: Common pathogens such as E. coli or fungi can disrupt the uterine environment and reduce fertility.
  • Poor vulvar conformation: “Windsucking” mares can draw in air and debris, leading to uterine contamination and infection.
  • Uterine abnormalities: Conditions like fibrosis or fluid retention can delay uterine recovery after foaling and lower conception rates during foal heat.

Hormonal and Metabolic Factors

Hormonal irregularities can disrupt estrus and ovulation, causing rebreeding challenges. Some of the common hormonal and metabolic factors include:

  • Stress-related hormonal imbalance: Elevated cortisol levels from physical, environmental, or herd dynamic stress can suppress reproductive hormones.
  • Equine Metabolic Syndrome (EMS): EMS affects insulin regulation, which can interfere with normal reproductive hormone activity.
  • Pituitary Pars Intermedia Dysfunction (PPID): Also known as equine Cushing’s disease, PPID can alter hormone balance and reduce fertility.

Age & Environmental Considerations

Several external and age-related factors can also impact broodmare fertility, including:

  • Age-related: Older mares often experience reduced fertility due to uterine scarring, decreased uterine clearance, and weaker pelvic tone.
  • Environmental stress: Factors such as extreme weather, hauling, or changes in herd dynamics can elevate cortisol levels and delay estrus.
  • Physical stress: The demands of foaling, lactation, or chronic pain can strain the horse's body and disrupt normal reproductive cycles.
  • Management practices: Poor perineal or vulvar hygiene, improper breeding handling, or poor farm management can increase the risk of infection or reproductive injury.
  • Seasonal irregularities: Shorter daylight hours or sudden seasonal changes can disrupt natural cycling and delay ovulation.

Nutritional Needs During Rebreeding, Pregnancy, and Lactation

Every stage of a broodmare’s reproductive cycle places unique demands on her body. Proper nutrition helps broodmares maintain condition, conceive consistently, and produce healthy foals.

Rebreeding

After foaling, a mare needs to recover from the physical demands of pregnancy and transition into lactation while preparing for her next breeding cycle.

Within days, most mares enter “foal heat,” their first fertile window postpartum. Breeding during this time is common to support an annual foaling schedule. However, rebreeding success depends on the mare’s body condition, nutritional status, and overall health.

During recovery, the uterus undergoes involution—a 30-day process where it returns to pre-pregnancy size. This period places considerable stress on the mare’s reproductive system. Because of this, horse owners preparing a broodmare for rebreeding must provide a well-balanced diet to help her recover from foaling, maintain optimal body condition, and support fertility for a successful conception.

Each nutrient plays a specific role in reproductive success and overall broodmare health, including:

  • Forage: High-quality forage should be the foundation of the diet, ideally fed free-choice. Forage provides broodmares with essential fiber, calories, and nutrients. This aids in digestive health, energy reserves, and reproductive health. Adding a high-quality concentrate feed or ration balancer to a forage-based foundation helps ensure there are no nutritional gaps in the mare's diet.
  • Amino Acids: Essential for tissue repair, uterine recovery, milk production, and muscle maintenance. Amino acids such as L-arginine and L-glutamine are particularly important for improving conception rates and post-foaling recovery.
  • Vitamins: Vitamins A and E strengthen the immune system, reduce oxidative stress, and support reproductive function, especially during late gestation and lactation.
  • Chelated Minerals: Highly bioavailable forms of trace minerals—including zinc, copper, and manganese—promote fertility, uterine health, and fetal skeletal development while improving milk quality.
  • Antioxidants: Help reduce inflammation and oxidative stress within the reproductive tract, supporting faster recovery and healthier pregnancies.
  • Energy: Calories from high-quality forage and balanced concentrates maintain body condition, hormonal stability, and can enhance reproductive performance.
  • Feed Quality: Forage-only or low-quality hay often lacks essential nutrients. Pairing premium hay or pasture grass with a high-quality concentrate feed or a ration balancer ensures complete nutritional support for both mare and foal.

Pregnancy

A pregnant mare’s diet needs little change early in gestation, but her nutritional demands rise steadily as foaling nears. Just like during the breeding phase, high-quality forage serves as the foundation of a balanced and nutritious diet. Adding a ration balancer or broodmare-specific feed helps supply the additional nutrients required for a healthy pregnancy.

During the final trimester, fetal growth accelerates, requiring gradual increases in key nutrients to support the developing foal and prepare the mare for lactation. These nutrients include:

  • Calories (Energy): To meet higher energy demands and maintain body condition.
  • Protein and Amino Acids: To support fetal tissue growth and prepare for milk production.
  • Calcium and Phosphorus: For skeletal development and proper energy utilization.
  • Copper: For connective tissue and cartilage formation in the growing foal.
  • Vitamins: Especially A, D, and E, which aid immune function, fetal growth, and reproductive health.

Foaling & Lactation

After foaling, the mare’s nutritional demands increase dramatically—comparable to those of a racehorse in intense training. Broodmares must produce nutrient-rich milk while recovering from foaling and preparing for another conception.

Free-choice access to high-quality forage provides the primary source of energy, but additional nutritional support is often necessary. During lactation, a mare’s feed intake should increase to about 3% of her body weight. A high-quality full-intake feed or ration balancer rich in amino acids, vitamins, and minerals helps maintain body condition, support milk production, and promote reproductive recovery.

Pre- and probiotics can also aid gut health and nutrient absorption, optimizing feed efficiency. While a slight drop in body condition during peak lactation is normal, balanced nutrition helps mares regain weight in time for the next breeding cycle.

Lactating mares also require significantly more water than non-lactating mares—often 50% to 80% more—to replace the significant fluid losses from milk production, which is about 90% water. Producing up to 3 gallons of milk per day and consuming more feed to meet energy demands both increase her need for constant access to clean, fresh water.

Overall, targeted nutritional support throughout lactation and the postpartum period promotes faster recovery, healthier foals, and higher conception rates when rebreeding.

Tribute Equine Broodmare Nutrition and Feed Formulations

A feed formulated for non-lactating or non-breeding mares will typically not provide adequate nutrition. Feeding a low-nutrient diet during this critical period can delay recovery and hinder her ability to conceive again quickly.

Instead, a broodmare's feed should be balanced and fortified with the essential nutrients that support her body during breeding, pregnancy, foaling, and rebreeding. While it's normal for mares to lose some body condition during peak lactation, with a high-quality forage and feed designed specifically for pregnant and lactating mares, most broodmares will regain body condition steadily in preparation for the next breeding cycle.

For mares consuming primarily grass hay (less than 50% legume), Tribute recommends feeds such as  Essential K® or Growth. For mares on legume-rich forage (greater than 50% legume), Alfa Essentials® or Alfa Growth® are excellent choices to complement this type of diet.

Broodmares require thoughtful management before and after foaling. With a balanced feeding strategy and careful adjustments to meet her changing needs, both mare and foal can maintain optimum health. If you have questions about your broodmare’s nutrition, our Tribute team is available to help develop a complimentary personalized feeding plan unique to your horse.

References

Article By:
Chris Mortensen, Ph.D.
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