HEART-RATE FLUCTUATIONS IN HORSE AT REST - BIOLOGICAL FACTORS OF VARIATION RELATED TO BEHAVIORAL-PATTERNS

Variability of heart rate was analysed within a sample of 30 horses in order to determine the influence of factors (animal, age, sex and breed) associated with different behavioural patterns. The heart rate fluctuations were analysed by computing the power spectral density of a series of heartbeat interval. A generalized linear model was used to compare the spectra and to reveal the effect of each factor: animal age, sex and breed The scale and shape of spectral densities were significantly different between animals. This individual variability was partly explained by, the sex and age effects while the breed effect had only a weak influence. Young hones and mares exhibited a greater heart rate fluctuation which may be related to their higher emotionality.