Reproductive behavior of stallions and mares: comparison of free-running and domestic in-hand breeding
Introduction
A long-standing curiosity in equine reproduction science and veterinary practice concerns what appears to be lower rates of sexual vigor and fertility and higher rates of sexual behavior dysfunction among hand-bred domestic horses compared to equids breeding at liberty. For example, stallions at pasture breed as often as every 1 to 2 h throughout the day and night with excellent sustained fertility (Bristol, 1982, Bristol, 1987, Henry et al., 1991; McDonnell and Bristol, unpublished 1987–1988; McDonnell, unpublished observations with semi-feral ponies 1994 to present). For most hand-bred stallions, libido and fertility diminish with breeding schedules of more than once or twice per day.
This paper presents a series of examples of observed differences in reproductive social organization and behavior of feral, semi-feral, and pasture-bred domestic horses compared to hand-bred horses that may influence reproductive efficiency and fertility. Based on these differences, changes in management and handling of domestic hand-bred horses are discussed as a strategy for improving their reproductive efficiency or for alleviating sexual behavior dysfunction in particular animals. These observations will be presented in the form of a series of concepts which I believe to be “important lessons” learned from observing free-running equids. For the most part, the concepts presented stem from the author's collective observations and data from field studies of domestic pasture breeding horses and semi-feral herds of ponies and donkeys together with laboratory research and clinical experience at the Equine Reproductive Behavior Laboratory of the University of Pennsylvania School of Veterinary Medicine at New Bolton Center over the period of 1981 through 1999. This experience involved collaboration with other scientists, students, veterinary practitioners, and breeding farm managers.
Section snippets
A harem stallion and his mares interact almost continually
A strikingly consistent feature of reproductive behavior among equids breeding at liberty is that a harem stallion and his mares are together and are interacting continually on a moment-to-moment basis year round (Bristol, 1982, Feist, 1976; McDonnell and Bristol, unpublished observations 1987–1988; McDonnell, unpublished observations 1994 to present). The frequency and intensity of the sexual interactions vary throughout the year, but nonetheless continue at a steady rate. Ongoing year-round
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2021, Journal of Equine Veterinary ScienceCitation Excerpt :Whereas housing of adult stallions in boxes with visual, auditory, and olfactory contact to their neighbours resembles the situation in bachelor stallions (without contact to mares), regular sexual activity at semen collections is more similar to the situation in harem stallions. This may stimulate some aggressiveness with stallions intending to fight their neighbours and round up their harem [1]. Influences on animal welfare, behavior and also libido and fertility are thus possible.