2938 Vet. Med. Basic Sciences Bldg.
2001 S. Lincoln Ave.
Urbana, Illinois 61802
By Joseph Hahn
University of Illinois
College of Veterinary Medicine
An ultrasound exam reveals that your mare is pregnant. As the mares owner, what nutritional needs should be considered to produce a healthy foal?
"Good body condition is important for good reproductive performance," says Dr. Ted Lock, a large animal veterinarian who specializes in reproduction at the University of Illinois College of Veterinary Medicine at Urbana. "Mares must be in adequate body condition before and during breeding season to get adequate reproductive performance."
Body condition scoring is a good method of estimating fatness in horses. This method assigns a numerical score, from one to nine (one being extremely thin and nine being extremely fat) using the following anatomical landmarks:
Optimal body condition is estimated at 4 to 6 for most performance horses and 5 to 8 for broodmares. Research has found that fatter mares (scores of 7 to 8) were excellent breeders.
"Nutritional requirements for the pregnant mare are the same as the maintenance and activity requirements during the first two-thirds of the pregnancy," says Dr. Lock. "It is important for the owner to individualize the feeding program for their horses." For example, a 1,000-pound pleasure horse with a body condition of 5, which exercises infrequently, will consume 2 to 2.5 percent of its total weight (20 to 25 pounds) daily in dry matter.
Dr. Lock does not recommend any change in the normal activity level of the mare during the first two-thirds of pregnancy. "These mares are safe to ride or compete as long as their nutritional requirements for maintenance and activity are being met."
The demands on the mare increase sharply in the third trimester of the pregnancy. The two factors responsible for the sharp increase are the development of the foal and preparation for lactation. While total feed intake does not need to increase during this time, the concentration of protein, energy, calcium, phosphorus and vitamin A should. It is very important during this period to have complete and balanced nutrition.
"After foaling, the mare has a high energy requirement due to lactation," says Dr. Lock. "It is at this time that underfeeding can lead to drastic weight loss." This may not be a big concern if the mare had adequate body condition before foaling.
Other health concerns for the pregnant mare are very similar to regular preventative medicine. Dr. Lock recommends an adequate parasite control program as well as vaccinations against the common diseases in your area. "Equine rhinopnemonitis virus is one of the common cause of abortions. Mares should be vaccinated in late pregnancy at five, seven and nine months." These are safe to give to the pregnant mare.
Finally, Dr. Lock notes that having a mare in adequate body condition with good nutrition will enhance the passive transfer of immunity to the foal. Mares colostrum provides antibodies against infection to the foal during the first few hours of nursing.
If you have any questions or would like further information
on this topic, please contact your local equine veterinarian.