Variation of Physiological and Behavioural Parameters during the Oestrous Cycle in Mares

SIMPLE SUMMARY: Apart from the sexual behaviour of mares in heat (oestrus), the rhythmicity of many physiological and behavioural traits during the whole oestrous cycle is scarcely known. We aimed at determining changes in cardiac activity variables, rectal and skin surface temperatures, relationship towards humans and other horses, and the time of standing and locomotor activity. Fifteen adult mares were examined in the morning and evening in oestrus (six days) and in dioestrus (five days—once every third day). Heart rate and rectal and surface temperatures are higher in the evening than in the morning and higher in oestrus than dioestrus. During oestrus, the mares show a better behaviour towards humans and other horses and are less locomotively active than during dioestrus. A rapid decrease in most of the physiological parameters occurs at the end of oestrus, whereas alterations in the behaviour towards humans and other horses appear at the beginning of dioestrus. The time of locomotor activity arises at the end of oestrus. The outcomes may contribute to the knowledge of, among others, mare owners who evaluate the oestrus by sexual behaviours without regarding other rhythmically changing variables. ABSTRACT: The behaviour of oestrous mares is well-known in horse breeding. However, alterations in their physiological and behavioural indices during the whole oestrous cycle are scarcely known. The objective of the study was to analyse changes in cardiac activity variables, rectal and superficial temperatures, behaviour towards humans and conspecifics, and the time of standing and locomotor activity in mares during their oestrous cycle. Fifteen adult mares in oestrus were examined in the morning and evening (six successive days) and in dioestrus (five days—once every third day). The oscillation of physiological and behavioural variables accompanies changes in mares’ sexual behaviour. Most physiological variables studied in oestrus indicate the elevated activity of the adrenergic nervous system and, opposite to that, both behaviour towards humans and conspecifics and the time of standing relate to a relaxed state. The end of oestrus, manifested by a rapid decrease in most of the physiological variables studied, is followed by changes of behavioural variables at the beginning of dioestrus. The time of locomotor activity arises at the end of oestrus. The outcomes may contribute to the knowledge of, among others, mare owners who evaluate the oestrus by mares’ sexual behaviours without regarding other rhythmically changing variables.