Is There an Ideal Rest Interval Between Races During Vaquejada in Which It Would Be Possible to Associate Best Performance and Welfare?

Vaquejada is an important Brazilian equine discipline. Understanding physiological adaptations of these athletes is crucial to improve properly performance, guaranteeing welfare. The objective of this study was to evaluate the influence of three vaquejada simulation tests (VST) on physiological parameters of horses and standardize a possible rest interval between races. Ten clinically healthy Quarter horses, 8.9 ± 4.3 year-old and 441.3 ± 25.0 kg, executed three VST, 5 days apart from each other. Vaquejada simulation tests consisted of two horses, a puller, and a helper, running with a bull on a soft sand track in which they must put the bull down. On M1, they ran three times with a 5-min rest between races; on M2, with a 10-min rest; and M3, with a 15-min rest. Clinical evaluation and blood sampling were made in all VST, before (T0), immediately after first run (T1), second run (T2), third run (T3) and at 30 minutes (T4), and 4 hours (T5) of recovery. Variables were statistically analyzed with a bifactorial comparison (P < .05). Exercise increased heart rate (HR), respiratory rate, body temperature (BT), lactate, triglycerides, packed cell volume, RBC, and hemoglobin concentration, with higher values in pull horses due to a more intense exercise. With 15-min of rest interval, helper horses showed lower values of glucose, aspartate aminotransferase, creatine kinase, BT, and higher values of triglycerides, also working at the same speed and distance with a lower HRmax and HRmed. Pull and helper horses had shown modifications of biomarkers. Furthermore, 15-min rest interval between races improved performance of helper horses as they used properly energy sources and cardiovascular function, respecting precepts of welfare.