Question
I have an eight-year-old pregnant Thoroughbred mare; she weighs about 1,200 lb (545 kg) and is moderately fleshy, a body condition score (BCS) of 6. She spends most of her on pasture, and only about four hours each day in a stall. She consumes about 2 lb (1 kg) balancer pellet and 2 lb (1 kg) of a sweet feed. I am happy with the way she looks now—at four months of pregnancy—but I have concerns regarding maintaining weight through the increasing demands of pregnancy without pasture. Your thoughts?
Answer
If your mare is usually an easy keeper, then you may just need to offer her additional hay during the later stages of pregnancy and lactation to maintain her weight and condition. Feeding a mixed grass/alfalfa (lucerne) hay will provide more calories, protein, and calcium per pound than typical, grass hay (orchardgrass or timothy).
Because you are feeding your mare a balancer pellet, she is getting appropriate levels of vitamins and minerals. This product can be fed throughout the pregnancy and lactation, if she can maintain her ideal weight and condition on a mainly forage diet.
Keep a close eye on your mare’s weight during late pregnancy and early lactation. The first two or three months of lactation are physiologically demanding for a mare, so additional calories may be necessary. By supplying her with sufficient energy, you will be sure she’s making enough milk to amply satisfy her foal’s nutrient requirements.
If your mare needs additional calories that cannot be met by an increase in good-quality hay, then changing to a feed formulated for broodmares and foals would the best option. Depending on the feed manufacturer, these types of feeds need to be fed at 5 lb (2.25 kg) or more per day to provide the appropriate levels of vitamins and minerals for pregnant and lactating mares.
If you find that it requires significant feed to keep the mare in adequate body condition during lactation, consider adding a fat supplement such as stabilized rice bran or vegetable oil. Horses find both of these palatable, and they can increase caloric content of the ration significantly.
As pasture growth declines or if there is no available pasture year-round, then supplemental vitamin E is recommended for horses fed only hay. When selecting a vitamin E supplement, it is best to choose a natural-source form, such as Nano•E, rather than the synthetic form of vitamin E. Natural-source vitamin E is more bioavailable to the horse, allowing a smaller amount of the product to be as effective as a larger dose of synthetic vitamin E. Supplementation of 1000-2000 IUs per day would be appropriate for your pregnant mare in addition to the vitamin E in the commercial feed.
