title: Environmental temperature has an influence on timing of the first ovulation of seasonal estrus in the mare.
abstract: A 10-yr retrospective analysis of the time of onset of seasonal ovulation derived from the records of a Thoroughbred horse stud at latitude 35 degrees S revealed a significant variation between years. The onset of seasonal ovulation was closely related to both the maximum (correlation coefficient r=0.56; P=0.09) and minimum (r=-0.67; P<0.01) environmental temperatures. The trend of the temperature rise and the levels attained in the weeks immediately prior to ovulation were similar for both the environmental maximum and minimum temperatures in all years of the study. Environmental temperature may therefore play an important adjuvant zeitgeber for the timing of the first ovulation of estrus in the mare.
authors.affiliation: Department of Obstetrics and Gynaecology, The University of Adelaide, The Queen Elizabeth Hospital, Woodville 5011, South Australia.
authors.forename: M V
authors.initials: MV
authors.lastname: Guerin
authors.forename: X J
authors.initials: XJ
authors.lastname: Wang