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Mare and Foal Nutrition Impacts Lifelong Health

July 2018 by Kentucky Equine Research,

Problems associated with excess body condition are well known among horse owners and include insulin resistance, laminitis, osteoarthritis and exercise intolerance. Recent research also shows the health of offspring of overweight mares may also be compromised.

Studies show, for example, excess maternal nutrition during pregnancy can alter glucose and lipid (fat) metabolism in foals until 160 days of age, and another study reported a higher incidence of osteochondrosis (OC) in foals born to dams that were fed concentrates during gestation, rather than forage only.

A more recent study* on broodmare nutrition during the last trimester of gestation and subsequent foal health revealed the following:

Growth of foals from 6-24 months of age was not affected by maternal diet;

Maternal undernutrition appeared to affect bone growth as foals from dams fed forage only had narrower cannon bones than foals from dams fed forage and barley;

Seven yearlings (29% of included yearlings) were diagnosed with OC lesions, but no difference in OC based on maternal nutrition was identified; and

The testicles of yearlings from forage fed dams were less mature than those from broodmares fed both forage and barley during gestation and lactation.

“This research also found that when yearlings were overfed between 19 and 24 months of age, up to approximately 135% of NRC energy requirements, overfeeding negatively affected yearlings from mares fed barley and forage more than yearlings from broodmares fed only forage,” explains Kathleen Crandell, PhD, a nutritionist for Kentucky Equine Research (KER).

Specifically, decreased insulin sensitivity and enhanced insulin levels suggestive of insulin dysregulation were observed in yearlings from mares fed both barley and forage but not in yearlings from forage only mares.

Consultation with an equine nutritionist can help owners design a feeding plan for broodmares and their offspring to ensure optimum health. Mares should be maintained in moderate body condition. If good quality pasture or hay is available, many easy keeping mares do well on balancer pellet, or appropriate vitamin and mineral supplement, such as KER All Phase or KER Gold Pellet, and free choice salt in a block and/or granules.

Apart from a balanced diet, supplements often recommended for mares and foals include omega-3 fatty acids (specifically EPA and DHA) and vitamin E. The antioxidant vitamin E has been shown to support improved fertility in mares that have trouble conceiving. KER Nano-E, a water-soluble, liquid formulation of vitamin E, which research has shown is six times more bioavailable than synthetic vitamin E, allowing a lower serve to have the same effect. KER Nano-E not only results in a greater peak in serum vitamin E, but also a more sustained rise in the serum vitamin E status, making it particularly beneficial horses that require long-acting antioxidant support.

In addition to benefits from feeding a natural-source liquid vitamin E, DHA and EPA fatty acid supplementation from fish oil has been shown to improve colostrum quality, and enhance passive transfer of antibodies to foals. Researchers are studying the effects of omega-3 fatty acids on estrous cycles and pregnancy rates of mares, with a possible connection to reproductive function. In mares, supplementation with fish oil has led to reduced prostaglandin secretion and increased progesterone levels, and this may aid embryo survival.   

Nutritionists uncovered interesting results when omega-3 fatty acids were fed to pregnant mares. The mares passed along the fatty acids to their foals in their milk. These foals seemed to have stronger immune status than foals suckling mares not fed omega-3 essential fatty acids.

KER EO-3 is a rich source of the long-chain omega-3 fatty acids, EPA and DHA, in a palatable liquid form. EO·3 can be fed to all horses, including foals, breeding and performance horses to improve the critical ratio of omega-3 to omega-6 in the diet, provide preferential precursors for production of less inflammatory local hormones and regulate gene expression to positively affect insulin sensitivity. With an omega-3 to omega-6 ratio of 12:1, feeding just 30ml of EO·3 daily can have a positive impact on your horse’s lifelong health. 

Remember, expert help is close by, so if you have any queries about your horses’ diet and want to double check they are getting everything they need, contact Kentucky Equine Research’s FREE Nutrition Consultation Service on 1800 772 198, email or submit a diet analysis through our website. Visit:

*Robles, M, C. Gautier, L. Mendoza et al. 2017. Maternal nutrition during pregnancy affects testicular and bone development, glucose metabolism and response to overnutrition in weaned horses up to two years. PLoS One. 12(1):e0169295.