The objective of this study was to verify the effect of increasing soybean oil addition levels in the concentrate, on the enzymatic activity CK (Creatine Kinase), LDH (Lactate Dehydrogenase), AST (Astarte aminostrafase), as an indication of energetic metabolism. Compond experimental diets were given with five oil levels (control, 6, 12, 18 and 24% concentrate). Twenty Arabian equines, average weight 400 kg were submitted to a 80 km endurance race on a treadmill. The endurance was divided into four 20 km rings with an average duration of one hour and 10 minutes. A significant effect of oil addition and the covered distance was observed on the variables AST, CK, LDH and they present the respective expressions AST and (7,045-0,2292x+0,007991x2+ 0,008517z- 0,0003282xz) CKand(8,06-,07020x+0,05546x2-0,001262x3+0,01204z+0,0006207xz) , LDH and (6,624-0,3522x+0,03448x2-0,0008382x3+0,02401z-0,0007489xz) . The oil is an important and well-used energy source for horses in exercise, because its addition to the diet of animals submitted to endurance test cause metabolic alteration that favored energy production. The animal metabolism save its energy reserves derived from glucose and favored the use of the oil. The smaller plasmatic activity of the AST, CK and LDH, enzymes with the addition of oil to the diets indicated directioning of the energy metabolism to β-oxidation. As the enzymes show several isoenzymes, it was concluded that the enzymes studied act widely on the energetic metabolism, favoring constant ATP reposition during all exercise.
β-oxidation; energy; horse; oil; performance
