Mares in late gestation (nine to eleven months) experience increased nutritional needs. Consistently meeting a broodmare’s energy and nutrition needs positively influences their reproductive abilities long term.
NUTRIENTS
Adequate intake of nutrients is important according to David Freeman, PhD, extension equine specialist with Oklahoma State University Cooperative Extension Service, who said, “Grain mixes have more digestible energy per pound and have supplemental protein, minerals and vitamins to ensure sufficient intake.”
According to Dawna Voelkl, DVM, assistant teaching professor and specialist in theriogenology at the University of Missouri College of Veterinary Medicine, “approximately 40 percent of fetal growth occurs in the last three months of gestation. And, the final 25-30 percent of fetal body weight is gained in the final month of gestation.”
Mark Russell, extension equine specialist with the University of Arkansas Cooperative Extension Service added, “Since foal growth averages about one pound per day in late gestation, and mare intake doesn’t increase, nutrients must be more concentrated.”
ENERGY
“Since each mare is different, energy needs will also be different and require variable feeding combinations of pasture grass, grain fed mixes and grass hay, being careful not to feed endophyte-infected fescue,” Russell said.
To meet the energy, crude protein and largely all of the micronutrient requirements, Voelkl recommended feeding commercially available, fortified and balanced 14 percent protein pellets.
Freeman and Russell agreed that breeders should include close inspection of pasture and brood mare’s condition during late gestation.
VITAMINS
Although vitamins A, D and E are all major concerns, Freeman said, “Vitamin A is the largest, followed by Vitamins D and E.”
Voelkl suggested that late pregnant mares be assured 20 mg/day vitamin A. “Since the vitamin content of pasture grass generally decreases when dried into hay, mares without access to pasture should receive supplementation,” she said.
PROTEIN
When it comes to crude protein, Voelkl said requirements increase by at least 20 percent in late gestation. Freeman said such requirements are best met by supplementing grain to pasture, or feeding higher protein forage to supplement a native grass pasture.
CALCIUM AND PHOSPHORUS
Calcium and phosphorus requirements also increase during late gestation. “Late gestation mares should be supplemented with up to 0.095 g Ca/kg body weight/day,” Voelkl said.
Because excess amounts of phosphorous relative to calcium interferes with calcium absorption, Voelkl recommended the ratio of calcium to phosphorous should be no less than 1:1, but may reach 6:1.
OTHER MINERALS
To ensure adequate amounts of sodium, potassium, magnesium, cobalt, iodine, copper, zinc and manganese, Voelkl suggested ad lib access to a commercially available vitamin and mineral block designed specifically for horses.
“Selenium and iodine should also be supplemented where the soil is deficient,” Voelkl said. “However, empirical supplementation, i.e., in the absence of evidence that the soil is deficient, may be dangerous and toxic to the mare and or foal.”
WATER
Unrestricted access to water should be available. “Late gestation mares maintained at approximately 70°F drink up to 50 liters (12-13 gallons) of water per day,” Voelkl said.
To birth healthy foals year after year, broodmares must have nutritional needs met for all stages of production but especially during late gestation.
