One of the most important development periods in the life of a foal is the last six 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 sixth 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 sixth month of gestation, so a fall check-up is an excellent idea.
The key elements of managing the pregnant mare are the following:
- Verify that all bred mares are pregnant. If there are open mares, now is the time to assess potential problems and prepare them for breeding the next season. If a mare was pregnant and has lost the pregnancy, now is the time to plan her program. If she needs to go under lights, that should happen about December 1. If Body Condition was an issue, now is the time to bring her up to desired 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!
- Lysine, methionine and threonine, the first three limiting essential amino acids, need to sufficient in the diet for placental and fetal development. Amino acids are more critical than crude protein.
- 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. A good vitamin program is also essential.
- 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.
Good quality pasture or forage may provide sufficient energy thru late gestation, but is unlikely to provide adequate amino acids, vitamins and minerals. An appropriate ration balancer product may be used from month five 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.