Mineral deficiency can affect both broodmare and her foal

For a healthy and well-nourished foal, start with a healthy and nourished mare

Reading Time: 3 minutes

The physical demands placed upon the body of the broodmare are extraordinary, especially as the number of offspring she is expected to bear increases.

These demands and expectations easily position the broodmare as a top performance horse in the horse industry. The broodmare relies on body reserves and nutritional resources to fund a smooth breeding cycle, gestation and lactation — a time period spanning roughly a year and a half from conception to post-weaning.

If the mare has received proper care and nourishment her body will be prepared to conceive, gestate, deliver, nurse and wean a healthy, robust and vibrant foal. This is the ultimate goal of reproduction and is also essential to the development of a sound adult horse.

Weaknesses and ‘holes’ in the early physical health of the foal can have far-reaching detrimental consequences. A foal needs a good nutrition even before it is born.

Current science and broodmare management practices generally recognize and accommodate the greater nutritional demands in her third trimester and during lactation. As important as this is, it is only one part of the holistic nutritional picture for the successful broodmare. Broodmares need exceptional nutrition all the time — 365 days a year. The mare’s body serves as both a storehouse and a vessel for the flow of energy and structural building blocks towards the beginnings of a new horse.

Body condition is a good visual indicator of the energy reserves available for reproduction. Unfortunately a similarly good visual indicator for the mineral status does not exist. The extent to which the mare drains the mineral reserves housed in her bony skeleton to accommodate the demands of foal development is not easily tracked, traced or measured — yet the contribution from this source is undoubtedly significant.

If not given an opportunity to replenish these mineral reserves through dietary support or given the sufficient time necessary to replenish the resources, then her reproductive health or the health of the foal will suffer. The effects of an exhausted nutrient reserve can be seen in both mares and foals in various manners.

Healthy reproduction in the mare expresses itself as smooth, uneventful transitions in the estrus cycle, a fertility rate of 80 to 95 per cent, and an uneventful pregnancy, delivery and lactation.

Lack of reproductive health can present itself as irregular heat cycles, poor conception rates, embryonic and/or fetal death or prolonged gestation. Mares in suboptimal reproductive health are more prone to complications during gestation, dystocia, rupture of the uterine artery, retained placenta and/or prolapse of the uterus.

Unfortunately the young foal also bears the cost of the mare’s diminished reproductive health for the mineral-deficient mare’s foal will be at greater risk for structural weaknesses such as bone and tendon deformities, umbilical herniations, reduced immunity and general ill thrift. Unfortunately at times it may not be possible to recapture the full health of a foal born to a mineral-deficient mare.

For example, research has shown broodmares that are copper deficient will potentially give birth to a foal with an increased risk of cartilage pathology. Once the foal, from a copper-deficient mare is born, copper supplementation to either the mare or foal will not reverse the damage done several months earlier during embryonic structural development.

The cartilaginous pathology present at birth places the foal at a significantly greater risk for developmental bone diseases and is a prelude to arthritis later on in life. Proper skeleton development in the embryo passes through the stage of ossification and mineralization of a cartilaginous framework.

If this process is interrupted in utero or incomplete due to deficient mineral resources then the likelihood for bone and joint pathologies in the young developing horse increases. The consequences, progression and outcome of the lesions may have different presentations, nonetheless the original insult in the embryonic framework remains defective. Minerals implicated in the bone health of the foal include but are not limited to the macronutrients such as calcium, phosphorus, and magnesium and the trace minerals such as selenium, copper, zinc, manganese, iodine, silica and boron.

The deficiency of selenium in the broodmare is another well-documented occurrence overtly affecting both the well-being of mare and foal. The selenium-deficient mare will have a greater chance of retained placenta and her foal will be predisposed to muscular weaknesses and have trouble standing, difficulty in suckling and swallowing, respiratory distress, and impaired cardiac function. Her foals are also more likely to have contracted tendons and angular limb deformities. Young foals with a difficult beginning may never fully recover.

The nutritional requirements of broodmares in the post-weaning period have received little attention in research, however, this may be the crucial time of replenishment for mares that will experience subsequent gestation-lactation cycles.

Mares are able to best regain their skeletal strength and re­mineralize in months when they are neither pregnant or lactating. During these times the mare will require the proper nutrition to create the storehouse of mineral reserves which will make a significant contribution to ongoing reproductive success. In certain circumstances an individual broodmare may even require a season of reproductive rest in order to adequately remineralize.

Proper nutrition throughout the year and timely well-thought-out breeding decisions prove to be valuable investments in the overall well-being of both the broodmare and her foal.

About the author


Carol Shwetz is a veterinarian focusing on equine practice in Millarville, Alberta.



Stories from our other publications