One of the most important development periods in the life of a foal is the last 6 months of gestation when the foal is developing in the uterus of the mare. The importance of this period was recognized in the Nutrient Requirements of Horses, Sixth Edition, when the Committee established that the nutrient requirements of the mare start increasing at the 6th month of gestation. Mares that foaled and were re-bred or were bred in the first four months of the calendar year may now be entering 6th month of gestation, so a fall check-up is an excellent idea.
The key elements of managing the pregnant mare are the following:
- Maintain appropriate body condition score. Mares should be at about a body condition score 6 when they foal so that they have sufficient energy reserves for early lactation as well as to maintain condition for re-breeding. If they need to gain weight, now is an excellent time to gradually increase the energy intake of the diet so they will be in the desired body condition at foaling. If they are a bit too heavy, increased exercise or slight reduction in energy intake may be useful while still maintaining amino acid, vitamin and mineral intake for the developing foal. Drastic weight loss is NOT recommended!
- Adequate protein/amino acid intake. Lysine, methionine and threonine, the first 3 limiting essential amino acids, need to sufficient in the diet for placental and fetal development.
- Adequate mineral and trace mineral intake. The mare needs to be receiving adequate calcium, phosphorus, magnesium, copper, zinc, manganese and selenium to provide minerals for the development of the foal and to build the foals own trace mineral reserves. Trace minerals are also critical for immune support.
- Vaccinations and deworming. A regular health care program should be developed in conjunction with a veterinarian so the mare is protected herself and can also produce antibodies to protect the foal when it nurses and receives the colostrum that contains maternal antibodies.
- If a mare was bred during the breeding season and is NOT pregnant, this is a good time to have this mare checked over carefully to determine why she did not settle or if she settled and aborted. She may require treatment to have her ready to breed in the next breeding season.
Good quality pasture or forage may provide sufficient energy thru late gestation, but may not provide adequate amino acids, vitamins and minerals. An appropriate ration balancer product may be used from month 5 to about month 10 or 11 of gestation to provide the missing nutrients. A feed designed for broodmares and foals can be introduced prior to foaling so that the mare is on the feed before she foals. This feed can then be increased after foaling to provide both the increased energy and the increased nutrients that are required for lactation, as well as providing nutrition for the foal when it starts to nibble on feed. Fresh clean water and free choice salt should also be available at all times.
Feeding the broodmare properly during gestation can help reduce the risk of developmental problems for the foal and help insure that the mare can be rebred in a timely manner to produce another foal the following year.