The Best Time of the Year, Pregnant Mares – The Chance for a Champion!

Many broodmares are in the last one third of gestation at this time of the year and some have already foaled. The latter part of gestation is one of the most important development periods in the life of a foal 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, earlier than previously believed.  During the last three months of gestation, the foal may be gaining a pound per day.

The key elements of managing the pregnant mare are the following:

  1. 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.  We are already thinking about re-breeding before she foals!
  2. 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.
  3. Adequate macro mineral, trace mineral and Vitamin 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. Vitamins A, D, E and B-Vitamins are all essential and should be included in a balanced diet.
  4. Vaccinations and deworming. A regular vaccination program should be developed in conjunction with a veterinarian so the mare is protected herself and can also produce the appropriate antibodies to protect the foal when it nurses and receives the colostrum that contains maternal antibodies. This is what protects the foal until it can be vaccinated and develop its own antibodies. The mare should also be dewormed as needed prior to foaling to make certain the environment of the foal is as “clean” as possible to reduce parasite contamination. Selective worming based on fecal count monitoring is becoming more and more important to reduce the risk of parasite resistance developing.

Good quality pasture or forage may provide sufficient energy thru late gestation, but may NOT provide adequate amino acids and minerals for optimal fetal development. A well designed ration balancer product may be used from month 5 to about month 10 or 11 of gestation to provide the missing nutrients. A well designed feed for broodmares and foals should be introduced prior to foaling so that the mare is on the feed before she foals to avoid the need for a sudden change in feed at foaling. 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 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.

Feeding and Managing Pregnant Mares: Prenatal Nutrition

Pregnant MareMany broodmares are in the last half of gestation at this time. The latter part of gestation is one of the most important development periods in the life of a foal 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, earlier than previously believed.  During the last three months of gestation, the foal may be gaining an average of one pound per day.

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.
  • 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 vaccination program should be developed in conjunction with a veterinarian so the mare is protected herself and can also produce the appropriate antibodies to protect the foal when it nurses and receives the colostrum that contains maternal antibodies.  This is what protects the foal until it can be vaccinated and develop its own antibodies.  The mare should also be dewormed as needed prior to foaling.

Good quality pasture or forage may provide sufficient energy thru late gestation, but may NOT provide adequate amino acids and minerals for optimal fetal development.  A well-designed ration balancer product may be used from month 5 to about month 10 or 11 of gestation to provide the missing nutrients.  A well-designed feed for broodmares and foals should be introduced prior to foaling so that the mare is on the feed before she foals to avoid the need for a sudden change in feed at foaling. 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 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 if desired.

Feeding Broodmares Properly

While visiting an area farm at feeding time I watched the owner give her mare an extra portion of feed since she was eating for two. I know she meant well, but the mare is not due until May. I explained to her that the “extra portion” really isn’t needed – she can continue to feed her mare on a quality maintenance program, including quality forage, until her last trimester.

During this time, the foundation of the foal’s body is being built, so quality nutrition is needed, but it doesn’t put a big strain on the mare just yet. When she reaches the last part of pregnancy, the foal’s body begins to actually grow by around 1 lb per day, and that is when the demands on the mares’ reserves begin. At that point, the owner would be wise to switch to a feed specially designed for broodmares and foals, as these feeds take into account the increased needs of the mare during that last part of pregnancy, and are formulated so a regular portion can be fed instead of having to provide “extra”.

Explaining further, I told her to gradually switch the mare to a broodmare or mare and foal ration, over a period of 5-7 days. Total dietary protein – not just from the grain, but from the grain and hay both – should be 12-14% (depending on amino acid balance) and balanced for all nutrients. It is important that the concentrate portion of the diet provide adequate protein, energy, calcium and phosphorus, as well as other vitamins and minerals. The foal is pulling significantly from the mare’s supply during the end of the pregnancy, and building up stores of nutrients for the first weeks of life on the ground. For example, the foal will not receive any copper from mare’s milk, so it has to store up sufficient levels while still in the womb to last it until it begins eating solids alongside its dam.

Finally, most mare & foal feeds are designed such that the mare should continue on the ration until she is through the heaviest part of lactation, and the foal can begin eating alongside her to adjust to solid feed, then can continue on the same feed through weaning – thereby reducing at least one stressful switch at that difficult time!