Mares in Mid-Pregnancy
We are often asked about the care and management of the broodmare during the middle trimester of pregnancy. This is an important time for the mare and her foal.
During the first and second trimesters, the foal is not growing that rapidly. Of course, if you ask the mare, she may think differently. The increase in the fetus' size is not the only development we are concerned about. The cell development for many of the systems that allow the body to operate is well under way at this time. So many of the essential nutrients such as trace minerals and vitamins, are critically important. Still, the need for energy and protein for maximum foal growth is not great.
Just because we only need to feed at maintenance level during the second trimester, that does not mean we can starve the mare. I know many of my clients would have to look up the meaning of ‘starve’, but occasionally we do see a pregnant mare that is very thin. To emphasize the importance of maintaining a moderate body condition, one of the methods of eliminating twins is to starve the mother. This approach is like walking a tight rope. The energy and protein of the ration are reduced to a level below maintenance. When the mare starts feeling the need to conserve her energy in preparation for more difficult times, she will start reducing the energy being allocated to the fetus. The mare is intentionally maintained at this level until one of the embryos stop growing. When growth has stopped, the embryo has died and will be absorbed by the uterus. The mare is then started back on the level of nutrition that will maintain her and the surviving embryo. While we agree it is critically important to avoid twins in the mare, there are other approaches we find more acceptable. The point is that reducing the nutrient level too far can be detrimental to maintaining the fetus.
To maintain the mare during the second trimester, she should be fed enough to provide a fat cover over the rib cage. This is easy to determine by laying the flat of the hand over the rib cage. You should feel a soft layer with the ribs underneath. The skin should move around easily, indicating there is fat between it and the rib cage that is providing lubrication. The mare in this condition will be able to meet all the fetus’ needs for energy and protein.
The greatest risk of nutritional deficiency is in the mineral and vitamin group. The mineral needs can be met by providing a trace mineral in either block or loose form. All of the horse’s needs are met with these products, with the possible exception of copper and lysine. However, we see few signs of deficiencies of these two micronutrients. The needs for them are probably met through the small amount of grain the mare receives. Any vitamin needs can be adequately met by supplementing with Clovite, the lowest cost vitamin source. As the mare enters the third trimester of pregnancy, a commercial product such as Mare Plus may be indicated. These products are formulated to meet the needs of the pregnant mare during this important last stage.
Deworming and vaccinations are just as important for the pregnant mare as for the rest of the herd. These can be given to the mare without concern for the health of the foal in the second stage of pregnancy. On the 5th, 7th and 9th months of pregnancy a rhinopneumonitis vaccination should be given.
In summary, the nutritional needs of the mare in the second stage of pregnancy can be met by providing ample hay and just enough grain to keep her in moderate body condition. Providing a free choice source of mineral and supplementing the feed with vitamins will meet the needs of these building blocks. Continue the mare on boosters for rhinopneumonitis, influenza, strangles, tetanus, sleeping sickness, and rabies, and be sure she is dewormed at least every six months. These simple steps will help the mare through this stage of pregnancy and prepare her for the all-important third stage.
CLICK BELOW TO DISPLAY A PRINTER-FRIENDLY COPY OF THIS ARTICLE
Select "Open this file from its current location," if you just want to print it out,
it will open in a simple word processing application, select the print button.
(unless you want to save this article in your computer's memory)
In Rich Text File (.rtf) Format:
MaresInMidPregnancy_101401.rtf
In Adobe Acrobat (.pdf) format:
MaresInMidPregnancy.pdf
