Effect of Work Experience and Position in the Plow Harness on Some Physiological Parameters of Horses Under Field Conditions

Six pairs of horses were studied during 6 consecutive days. One horse in each pair had working experience. The position of the 2 nonhuman animals in the plow harness was alternated each day. Some physical and physiological parameters were measured at different stages during each workday. A split-plot design with repeated measures was used with position in plow harness and work experience as factors. Work speed and force were similar in all pairs (p > .05). There was no effect of position in the plow harness on any of the variables evaluated (p > .05). Inexperienced animals had higher average respiratory rates (p < .01) and sweat scores (p < .05) than did experienced horses. For all variables, minimum values were observed at the beginning of the workday, after the 30-min break, and 30 min after the end of the workday. Increases in the parameters measured (p < .01) were detected after 1 hr of plowing, reaching maximum values at 2.5 hr of continuous work. Cortisol levels increased from 39.0 12.4 ng/ml at 9:00 a.m. (before work) to 84.0 20.8 ng/ml at the end of the workday. We concluded that position of the horse in the plow harness had no effect on the variables measured, whereas work experience significantly affected only respiration rate and sweating.