title: Seasonal changes in ovulatory activity, plasma prolactin, and melatonin concentrations, in mouflon (Ovis gmelini musimon) and Manchega (Ovis aries) ewes.
abstract: Seasonal changes in ovulatory activity, plasma prolactin and melatonin concentrations were monitored in a wild (Mouflon) and a domesticated (Manchega) breed of sheep, both originating and living under similar latitudes (40 degrees N). Mouflons express ovarian cycles significantly later than Manchega ewes (October vs. July, P < 0.001); however, they ended cycling one month later than Manchegas (April vs. March, P < 0.05). While prolactin concentrations were high when Manchega ewes started to cycle, they were at their lowest concentrations when Mouflons started cycling. Overall, mean prolactin concentrations were higher (P < 0.001) in Mouflons than Manchegas throughout most of the year. Within the limits of sampling frequency, the duration of melatonin secretion was similar in both groups during the solstice and equinox periods; however, the amplitude was lower (P < 0.01) in Mouflons than Manchegas during the solstice periods. The significant breed differences in the seasonal hormonal changes may be attributed to a genetic influence in the endocrine responses to the same photoperiodic cues.
authors.affiliation: Dpto. Reproducción Animal y Conservación de Recursos Zoogenéticos, SGIT-INIA, Madrid, Spain. moreno@inia.es
authors.forename: J
authors.initials: J
authors.lastname: Santiago-Moreno
authors.forename: A
authors.initials: A
authors.lastname: López-Sebastián
authors.forename: A
authors.initials: A
authors.lastname: González-Bulnes
authors.forename: A
authors.initials: A
authors.lastname: Gómez-Brunet
authors.forename: P
authors.initials: P
authors.lastname: Chemineau
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000502:physiology; D000835:Animals, Wild / Q000502:physiology; D005260:Female; D008550:Melatonin / Q000097:blood / Q000378:metabolism*; D010053:Ovary / Q000502:physiology*; D010060:Ovulation; D017440:Photoperiod; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D012621:Seasons; D012756:Sheep / Q000502:physiology*; D013030:Spain
chemical_list: D011388:Prolactin; D008550:Melatonin