An experiment was conducted to determine the effect of feeding blends of grains naturally contaminated with Fusarium
mycotoxins to mature, exercised horses, and to test the efficacy of a polymeric
glucomannan mycotoxin adsorbent (GM
polymer) in preventing Fusarium
mycotoxicoses. Six mature, mixed-breed mares with an average BW of 530 kg were assigned to one of three dietary treatments for 21 d in a replicated 3 x 3 Latin square design. Feed consumed each day was a combination of up to 3.5 kg of concentrates and 5.0 kg of mixed timothy/alfalfa hay (as-fed basis). The concentrates fed included 1) manage; 2) blend of contaminated grains; and 3) contaminated grains + 0.2% GM
polymer (MTB-100, Alltech Inc., Nicholasville, KY). Concentrates containing contaminated grains averaged 11.0 ppm
deoxynivalenol, 0.7 ppm 15-
acetyldeoxynivalenol, and 0.8 ppm
zearalenone (as-fed basis). Feed intake and BW were monitored over a 21-d period. Horses were maintained on a fixed exercise schedule throughout the experiment. At the end of the experiment, each horse completed a time-to-
fatigue treadmill step test. Variables measured during pretest, each step of the test, and 5 and 10 min posttest were as follows: 1) time-to-
fatigue, 2) heart rate, 3) hematological variables, and 4) serum
lactate concentration. Each step consisted of 2 min of fast trot with a 2% increase in incline after each 2 min. Feed intake by horses fed contaminated grains was decreased compared with controls throughout the experiment (P < 0.05). Supplementation of 0.2% GM
polymer to the contaminated diet did not alter feed intake by horses compared with those fed the unsupplemented contaminated diet. All hay was consumed regardless of concentrate fed.
Weight loss from 0 to 21 d was observed in horses fed contaminated grains compared with controls (P < 0.05). No effect of diet was seen on variables used to measure athletic ability, although the results showed an expected response to exercise for a fit horse. We conclude that exercised horses are susceptible to Fusarium
mycotoxicoses as indicated by appetite suppression and
weight loss.