Time of Feeding Critical for Performance

One of the most frequently asked questions regarding feeding the performance horse is when to feed before a competition. Several studies have evaluated how feeding grain before exercise affects plasma concentrations of nutrients and hormones and substrate utilization during exercise (Rodiek et al., 1991; Zimmerman et al., 1992; Lawrence et al., 1993; Lawrence et al., 1995; Stull and Rodiek, 1995; Duren et al., 1998). In each of these studies, a pre-exercise concentrate meal suppressed free fatty acid (FFA) availability and enhanced glucose uptake by muscle during exercise. Forage was not fed with the concentrate in any of these studies. Thus, it is not known whether feeding hay along with grain will alter substrate availability during exercise. Therefore, a series of experiments was conducted to first evaluate how feeding forage along with grain influences plasma variables and water intake and then to determine whether these changes affect exercise performance. Additionally, a study was conducted to determine how forage alone affects exercise response. Since time of feeding is particularly important for three-day event horses, the exercise test used was a competition exercise test (CET) performed on a high speed treadmill and designed to simulate the physiological and metabolic stresses of the speed and endurance test of a three-day event (Marlin et al., 1995).