New Perspectives on Foal Nutrition

Lawrence said these studies have peaked her interest in other components of mare’s milk and the foal’s GI tract.


During the 2017 University of Kentucky (UK) Equine Showcase, Laurie Lawrence, PhD, professor in the department of animal and food sciences at UK, gave a talk regarding the equine neonatal diet and some recent foal nutrition research she and her team have conducted.

She recognized contributions made by several collaborators, including Morgan Pyles and Susan Hayes, of UK’s Department of Animal and Food Sciences, and Michael Flythe, PhD, of the USDA Agricultural Research Services unit, located on UK’s campus.

A new foal’s diet consists mostly of milk, Lawrence said. Recently, she and colleagues completed a preliminary study in which they analyzed mare’s milk content. They obtained milk samples from 16 Thoroughbred mares within an hour of foaling, approximately 24 hours after foaling, and approximately three days post-foaling, and analyzed the samples’ insulin and cortisol content.

The team found that both cortisol and insulin were present in mare’s milk, with especially high levels in colostrum. Lawrence believes this could indicate that there are other hormones or growth factors in colostrum. And although she’s not entirely sure why cortisol and insulin were present in mild, or how important these findings are, she said, “Mother Nature hardly does anything without a reason.”

Another important part of foal nutrition is the transitions from a milk-based diet to fiber-based one. Microbes in the large intestine are important for digesting the fiber that’s the backbone of an adult horse’s diet, and understanding how foals acquire these essential bacteria is, therefore, an important part of the dietary transition.

This led to the second study Lawrence described in her presentation, in which she and colleagues assessed mare and foal fecal samples starting at birth and throughout the foal’s first month of life. The team paid special attention to the samples’ microbial content to better understand the foal’s microbial community.

From Day One, foals had starch-utilizing bacteria in their fecal samples. Theoretically, however, all milk components should be digested in the small intestine, Lawrence said.

Based on the abundance of starch-utilizing bacteria in foal fecal samples, Lawrence concluded this indicates that some starch, sugar, or carbohydrates from milk must be reaching the foal’s large intestine, thus resulting in the starch-utilizing bacteria’s presence.

In humans, Lawrence explained, oligosaccharides (a type of carbohydrate) in milk are believed to be important to microbial colonization in the gut. Based on their study findings, her team plans to look more closely at carbohydrates in mare milk.

This new information is relevant in several ways, Lawrence said. Firstly, microbes in the horse’s gut helps with food digestion, which makes them important to assess and understand. Microbes also aid in protecting the digestive tract from pathogens. Foal diarrhea is a problem nearly every breeder encounters, and a better understanding of foals’ gastrointestinal (GI) tract microbial colonization could reveal factors that increase the risk of neonatal diarrhea.

Going forward, Lawrence said these studies have peaked her interest in other components of mare’s milk and the foal’s GI tract. In the future, she would like to characterize mare milk more thoroughly, identify the “first responders” that colonize a foal’s digestive tract, and identify the factors that improve or impair the colonization of the foal GI tract.

Maddie Regis is a sophomore marketing major at UK and communications and student relations intern within the UK Ag Equine Programs.

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