According to a new study, magnesium has been deemed an unreliable supplement to calm an overly flighty horse, as reported by Horse Talk.

The study, “Does Oral Magnesium aspartate supplementation affect reaction speed in horses of different breeds?” tested 18 horses and observed their behavior after supplementation. Of the 18 horses in the study conducted by Charles Sturt University in New South Wales, Australia, there were six ponies, six Arabians and six Thoroughbreds. The study was done in collaboration with Waltham Equine Studies Group, which provides the science behind the feed brand Spillers. The idea behind this study came from a previous one in 2015, conducted on Standardbreds, which gave positive correlations between supplementation of magnesium aspartate and calm behavior. The goal was to reduce reaction time in horses, and the study’s results showed the average reaction time reduced by one-third. 

In this new study, the 18 horses were fed three different diets in random order over 7 days. The different diets included: a control hay-based diet, which provides the National Research Council’s recommendations for magnesium; the control diet plus an additional supplement of magnesium (10g/500kg horse); and the control diet plus an additional supplement of aspartate in the form of magnesium aspartate or sodium aspartate. 

As a result, the horses in the study showed varying results. Some increased reaction speed and others decreased after being fed the magnesium aspartate or the sodium aspartate, while there were no significant effects seen after consuming the control diet. In this case, it can’t be said that the magnesium or the aspartate had a consistent effect on the animals. 

“As it stands these results suggest that magnesium supplementation cannot be relied on to modify horses’ reaction speeds,” says Clare Barfoot, Spillers research and development manager. “It may be wiser to focus on training and habituation to stressful situations to help manage reactive behavior, rather than to rely solely on magnesium-based products.”