Published: July 2020 | Updated: December 2022
The healthier the mare, the healthier the foal; this statement certainly checks out since foals receive their nutrition from the dam. And it all starts with colostrum--the very first mammary secretions transferred from mare to foal.
Let’s answer some frequently asked questions to ensure that your mares and foals are the healthiest they can possibly be.
How Long Does a Mare Produce Colostrum?
The thick, yellowish fluid produced in the mare’s udder during the last 2-4 weeks of gestation as a result of hormonal changes is known as colostrum. This fluid is packed with protein, fat, vitamins, sugars, minerals, and most importantly, maternal immunoglobulins (antibodies) which are the building blocks of proteins utilized by the immune system to fight off infection.
Mares produce colostrum for no more than 24 hours before their normal milk comes in, but this “liquid gold” is the only source of antibodies for a newborn foal. In fact, it can literally mean the difference between life and death in the foal’s first days since the newborn immune system is not yet mature.
Horses differ from some other animal species because immunoglobulins aren’t transferred from mare to foal during pregnancy. Because of this, newborn foals are highly susceptible to bacterial or viral infections. Fortunately, however, good-quality colostrum provides immunity to the foal that lasts anywhere from 6-12 weeks until the foal’s immune system can function on its own.
How Much Colostrum Does a Foal Need and When Do They Need it By?
Colostrum is only available for the first 24 hours after the mare gives birth, and the best-quality colostrum is produced in the first eight hours after foaling. For a short time after birth, a newborn foal is able to absorb the large immunoglobulin proteins through the wall of their small intestine and into their bloodstream. This is known as passive transfer.
The absorption of immunoglobulin proteins is greatest during the first 6-8 hours after birth. After 24 hours, however, absorption is no longer possible due to changes in the foal’s intestinal system. Likewise, concentrations of immunoglobulins in the mare’s colostrum begin to rapidly decline after the first 24 hours after the foal’s birth.
High levels of colostrum IgG (the most common antibody) via passive transfer are vital for a newborn foal’s health. Ideally, foals should ingest up to half a gallon (2-4 liters) of colostrum within the first 12 to 24 hours of life.
What Happens if the Foal Doesn’t Get Enough?
Some mares have higher-quality colostrum (with higher levels of IgG) than others, and this often comes down to their own health. If the mare has nutrient deficiencies, is ill, or has poor gut health, her colostrum may not fully protect the foal, and according to researchers, poor colostrum quality is one of the primary causes of immunity transfer failure for foals.
The appearance of your mare’s colostrum can help you determine the quality of it. It should be thick, sticky, and golden or yellow in color.
Watery or opaque colostrum usually means that there is a problem. Fortunately, there are tests that can quickly assess quality, one of the most popular ones being the handheld Brix refractometer.
However, keep in mind that even if the colostrum is high-quality, foals may not get enough colostrum for the following reasons:
- If the foal is too weak to stand and nurse without help;
- If the mare had premature lactation, leaking colostrum before the foal could ingest it; or
- If the foal fails to adequately absorb colostrum for whatever reason.
Without the ingestion of enough colostrum or enough quality colostrum, the foal is at risk of developing life-threatening conditions.
An IgG test should be run within the foal’s first 24 hours of life to ensure they have absorbed enough antibodies from colostrum. If not, your veterinarian can provide antibodies through equine plasma transfusion.
How Can You Ensure That Your Mare Will Produce High-Quality Colostrum?
Nutrition is paramount for broodmares. For the first seven or eight months of gestation, mares do not necessarily need more calories, but they do require sufficient intake of high-quality forage (pasture or hay) as well as a source of essential vitamins and minerals. During the last three to four months of pregnancy, however, the mare’s energy requirements will increase.
Providing high-quality, free-choice forage will help to add calories. While you don’t want to overfeed your mare, additional calories can be provided with concentrates, rice bran, or healthy fats such as flax oil. Always ensure that either loose salt or a salt block is available and that the mare has clean, fresh water available at all times.
One caution for pregnant mares: avoid pastures or hay high in fescue which can be infected with an endophyte that causes prolonged gestation, difficult delivery, and lack of milk. Fescue can also impact the quality of the mare’s colostrum or cause them to produce no colostrum at all.
Another thing you may want to consider is adding probiotics to your mare’s diet since studies have shown that gastrointestinal microbiota play a crucial role in a horse’s nutrient digestion, as well as their overall health.
One study showed that a supplement rich in live yeast increased IgG production in colostrum. In this study, researchers supplemented mares with the probiotic for the last eight days of gestation, finding significant improvement in both the initial IgG and persistence of IgG qualities of colostrum.
Having healthy foals is important for any breeder, and it all starts with the mare. Prioritizing nutrition and adding probiotics may mean the difference between a strong, healthy foal and one that is prone to infection.