The objective of this research was to estimate, by haematophysiological parameters, the physical performance of horses under exercise of mid intensity and fed diets with two levels of vegetal oil (250 and 500 g/day). Eighteen castrated thoroughbred horses aging from 4 and 8 years old and averaging body weight of 456±2.90 kg were alloted to a split plot approach with repeated measures over time in a completely randomized design, with the collection times in the sub-plots and the soybean oil levels (0, 250 and 500 g per horse per day) in the plots. During 30 days, the horses were fed 8.40, 7.95, and 7.30 kg/day of diets with 0, 250 and 500 g of oil, respectively, divided in three daily feeds. At the end of 30 days, the exercise test was performed with all horses, during 2 hours, at large trot. At the beginning and at the end of the exercise, the levels of glucose, lactate, haematocrit, body temperature were estimated. The heart and respiratory rates were taken at the beginning, 1 and 2 hours of exercise and 15 minutes after the end of the exercise. Interaction of collection times <FONT FACE=Symbol>´</FONT> dietary oil levels on the levels of glucose, lactate, and haematocrit, body temperature, and heart and respiratory frequencies was observed. The supplementation of 250 and 500 g of oil in the diet of equines under exercise of mid intensity increased haematophysiological performance, that can improve horse athletic performance. The horses daily fed 500 g of oil showed better recovery post-trial, and that is verified by the values of heart rate and of haematocrit.
glucose; head rate; haematocrit; lactate
