Thanks to climate change and increasing amounts of grain blends, the prevalence of feed-borne mycotoxins (dangerous toxins exuded from molds) is on the rise, according to Trevor Smith, PhD, of the University of Guelph, Canada. Smith, a professor with a research interest in feed and food toxicology, discussed the effects of one of the most common families of mycotoxins–Fusarium–on horses at the Veterinary Sport Horse Symposium, held Sept. 22-24 in Lexington, Ky.

Smith described two studies performed at Guelph by Susan Raymond, a PhD student in his lab: The first involved feeding a group of 12 mature, nonexercising mares grains contaminated with Fusarium mycotoxins, along with feeding a control group of 12 similar mares grain without contamination. The researchers measured the horses' grain concentrate intake every seven days for three weeks and they noted decreased consumption among the mycotoxin-fed horses at each time point, compared to the control animals. In the second study researchers evaluated the same diet in 12 mares, but they added exercise to the horses' routine. Researchers still witnessed a decline in concentrate consumption, but it was not as severe because the exercise increased the horses' energy requirements and forced them to eat. Weight loss was recorded in this study, whereas it was not in the study of nonexercising mares.

"Feeding grains contaminated with Fusarium mycotoxins can alter the metabolism and reduce performance," Smith concluded. "This can lead to financial losses for producers