title: Characterization of the reproductive cycle in female bharals (Pseudois nayaur) based on the changes in serum progesterone concentrations and parturition season.
abstract: The purpose of present study was to determine annual changes in serum progesterone (P(4)) concentrations and to clarify basic reproductive characteristics, such as breeding season, estrous cycle, and puberty in female bharals (Pseudois nayaur). Blood was collected from 9 female bharals once or twice weekly for approximately one year. Serum P(4) concentrations were determined by radioimmunoassay. Serum P(4) concentrations showed remarkable and cyclic changes between November/December (winter) and May/June (late spring). The mean estrous cycle was 24.9 +/- 0.5 days. Chasing insistently to other females and discharge of mucus from the vulva were observed around the time when the serum P(4) concentrations began to increase. The chasing behavior and discharge of mucus were considered to be external indicators of estrus in female bharals. Serum P(4) concentrations of a pregnant female had non-cyclic changes, and the values remained high. In this study, all 37 deliveries were between April and September, and about 70% of these were concentrated in May and June. The conception month determined on the day of birth was between October and April for all animals, and the most common month was in December (54%). This month corresponded to an early stage of the period when the serum P(4) concentrations changed cyclically. These results indicate that many female bharals become pregnant at the beginning of the breeding seasons and, if they do not become pregnant, the estrous cycle, about 25 days in length, is repeated.
authors.affiliation: Laboratory of Animal Reproduction, United Graduate School of Agricultural Science, Gifu University, Yanagido, Gifu, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kusuda
authors.forename: Hirotada
authors.initials: H
authors.lastname: Nagami
authors.forename: Kayoko
authors.initials: K
authors.lastname: Ueda
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nishikaku
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nakagawa
authors.forename: Toyoharu
authors.initials: T
authors.lastname: Takida
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kurita
authors.forename: Koji
authors.initials: K
authors.lastname: Uemichi
authors.forename: Masaki
authors.initials: M
authors.lastname: Fukai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kubota
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ueda
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ooe
authors.forename: Kazuo
authors.initials: K
authors.lastname: Okuda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kusunoki
authors.forename: Osamu
authors.initials: O
authors.lastname: Doi
mesh_terms: D000818:Animals; D030762:Estrous Cycle / Q000097:blood / Q000502:physiology*; D005260:Female; D008297:Male; D036801:Parturition; D011374:Progesterone / Q000097:blood*; D012418:Ruminants / Q000097:blood / Q000502:physiology*; D012621:Seasons
chemical_list: D011374:Progesterone