Length of gestation periods of horses and ponies belonging to different breeds

Abstract

The mean gestation periods of mares belonging to different horse and pony breeds common in The Netherlands have been calculated using data from the birth registers of five stud-book societies. The following mean values have been determined: Fjord pony: 342.2; Haflinger pony: 341.3; Draught horse: 343.3; Shetland pony: 337.2; and Frisian horse: 337.7 days. The variation in the mean gestation period is greater in horses than in cows, sheep or pigs. Colts are carried a little longer than fillies. Differences between years are not significant, but differences between the various breeds have been determined. Shetland foals born before 1 June are carried longer than those born after 1 June. The gestation period for mares of this breed mated at 2 years, is significantly longer than for those mated at more than 2 years.The length of the gestation period in horses is possibly affected by physiological factors other than those influencing the gestation period in some other farm animals.

Factors affecting gestational length in the Mangalarga Paulista breed

“…These results differ from the majority of data for different breeds, in which the gestation length for colts was longer than that for fillies (Bos and Van Der Mey, 1980;Davies Morel et al, 2002;Pérez et al, 2003;Valera et al, 2006;Satué et al, 2011a b;Aoki et al, 2012;McCue and Ferris, 2012). Only few publications were not able to detect a significant influence of gender on the length of gestation (Campitelli et al, 1982;Valente et al, 2006), as it was found in our study.…”

Genetic study of gestation length in andalusian and arabian mares

“…We observed longer gestation periods in both younger and older mares ( Table 2). Similar results were obtained in most studies (Akkayan and Demirtel, 1974;Platt, 1979;Bos and Van Der Mey, 1980;Demirci, 1988). This was postulated to be due to a decrease in uterine/placental nutritional efficiency (Pashan and Allen, 1979) and/or the metabolic-hormonal drive to grow (Gluckman and Hanson, 2004), as a consequence of age and the multiparous state, slowing intrauterine growth and prolonging gestation.…”

“…The length of full-term pregnancies varies within a short range of days, even though a certain variability can be appreciated and justified genetically as much as by environmental factors. In horses, the range of variability of the gestation length is larger than in other domestic species (Bos and Van Der Mey, 1980), probably due to the fact that their long gestation period is influenced by physiological factors that do not influence the gestation lengths of other species (for instance, embryonic diapause, reported by Lofstedt, 1992). A number of studies have confirmed these wide variations in gestation length for various breeds of horses (Pérez et al, 2003).…”

Reproductive seasonality in captive wild ruminants: implications for biogeographical adaptation, photoperiodic control, and life history

“…One factor supporting ruminant radiation into higher latitudes could be that, aside from the giraffids, their gestation periods are below 1 year and can be comparatively short ( cf . the gestation period of domestic cattle at about 278 days compared with that of similar‐sized domestic horses at about 340 days ‐ Jafar, Chapman & Casida, 1950; Bos & Van der Mey, 1980), which makes an adaptation to seasonal environments feasible without loss of a vegetation period for the interbirth interval (Kiltie, 1988). As stated in , the fact that species with gestation periods longer than a seasonal cycle live or lived at higher latitudes indicates that while a short gestation period may be an advantage at higher latitudes, it is not a precondition for expansion into such regions.…”