Maximum permissible load for Kiso horses trotting over a short, straight course.

Abstract

This study aimed to determine the load-bearing capacity of trotting Kiso horses using gait analysis. Ten Kiso horses with a height at withers of 128cm were included. Their riders were fitted with a marker (70mm in diameter placed on their chest) recorded by two digital DVD cameras while trotting along a short, straight course. In total, eight tests were performed for each horse: the first with a 70kg load; six with randomly loaded weights ranging 80-130kg; and then a final test again with a 70kg load. Three-dimensional movement of the marker was analyzed using a motion capture system. The time series of vertical displacement of the marker underwent spectrum analysis by the maximum entropy method, and the autocorrelation coefficient was calculated. The first two peaks of the autocorrelation were defined as symmetry and regularity, and their sum was defined as stability. Regularity in the 120kg test (0.54) was lower than that in the first 70kg test (0.61), and stability in the 120kg test (1.31) was lower than that in the first 70kg test (1.42). We concluded that the maximum permissible load for a trotting Kiso horse is <120kg, which represents 31% of its bodyweight.