title: Reproductive performance, metabolic and hormonal profiles of Santa Inês ewes in winter and summer under tropical conditions.
abstract: The study aimed to evaluate the reproductive, metabolic and hormonal profiles of Santa Inês ewes during winter and summer in the tropical climate of Rio de Janeiro State, Brazil. The ewes (n = 16) were prepared for induction of synchronised oestrus with a short-term hormonal treatment, and follicular dynamics were assessed with ultrasonography. Blood samples for biochemical and hormonal analyses were collected on days zero, six and eight of the protocol at 7, 13 and 19 h. Reproductive behaviour did not differ (P > 0.05) between seasons. Based on ultrasonography data, the ovulation rate was 100% in summer and 81.3% in winter. Most of the ewes showed double ovulation in summer, and the diameter of the largest and second largest follicles differed (P < 0.05) between seasons. Among the biochemical parameters, plasma glucose, plasma urea and serum albumin differed (P < 0.05) between the study periods. Regarding the hormonal profile, higher serum triiodothyronine, thyroxine and prolactin concentrations (P < 0.05) were observed in summer. The average progesterone concentrations demonstrated low reproductive seasonality. In conclusion, the reproductive performance of the ewes was superior in summer, and higher levels of plasma glucose and serum albumin during this season may have played a role in the observed ovulation rates. The higher levels of serum prolactin and serum thyroxine in summer demonstrated that these compounds were not involved in the regulatory mechanisms underlying the onset of anoestrus in these Santa Inês ewes under tropical conditions.
authors.affiliation: Departamento de Patologia e Clínica Veterinária, Faculdade de Veterinária, Universidade Federal Fluminense, Rua Vital Brasil, 64, Santa Rosa, Niterói, Rio de Janeiro, 24320-340, Brazil, mariobalaro@hotmail.com.
authors.forename: Mario Felipe Alvarez
authors.initials: MF
authors.lastname: Balaro
authors.forename: Felipe Zandonadi
authors.initials: FZ
authors.lastname: Brandão
authors.forename: Anna Beatriz Veltri
authors.initials: AB
authors.lastname: Peneiras
authors.forename: Eunice
authors.initials: E
authors.lastname: Oba
authors.forename: Jeferson Ferreira
authors.initials: JF
authors.lastname: da Fonseca
authors.forename: Nádia Regina Pereira
authors.initials: NR
authors.lastname: Almosny
authors.forename: Elyzabeth
authors.initials: E
authors.lastname: da Cruz Cardoso
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001938:Brazil; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D010060:Ovulation / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000097:blood; D012098:Reproduction; D012621:Seasons; D012756:Sheep / Q000502:physiology*; D014329:Tropical Climate
chemical_list: D011374:Progesterone; D011388:Prolactin