title: Characterizing emergence and divergence in the first follicular wave in a tropically adapted Bos taurus breed.
abstract: Tropically adapted Bos taurus breeds are descended from the cattle which were brought from the Iberian Peninsula to Latin America by the colonizers and which adapted over time to local conditions. These breeds have become a genetic treasure that must be preserved. The objective of this study was to characterize ovarian follicular emergence and divergence in tropically adapted B. taurus cows and heifers. Cyclic heifers (n = 11) and nonlactating, multiparous cows (n = 11) were examined at 8-hour intervals using ultrasonography starting on the day following the final application of PGF2α, which was used to synchronize the estrous cycle, and ending 5 days after ovulation. Blood samples were collected immediately following the ultrasonographic examinations in order to evaluate FSH and estradiol-17β (E2) concentrations. The interval between ovulation and follicular wave emergence (11.6 ± 3.3 hours vs. 20.3 ± 2.5 hours, P < 0.05) and ovulation and follicular wave divergence (52.4 ± 5.2 hours vs. 71.8 ± 4.1 hours, P < 0.05) was shorter in the cows than in the heifers, respectively. Plasma FSH concentrations increased (P < 0.05) and serum E2concentrations decreased earlier in cows than in heifers before ovulation. Following follicular wave emergence, no difference in follicular development was found between the cows and the heifers. Consequently, following follicular wave emergence, the data from both the cows and the heifers were combined and categorized by dominant follicle (DF) and second largest follicle (SF). The DF and SF were identified at the same time (P > 0.05). The mean number of small (≤4 mm, 7.2 ± 5.1) and medium (4 to ≤ 8 mm, 6.8 ± 3.5) follicles was greater than that of large follicles (≥8 mm, 0.6 ± 0.5) from ovulation until 5 days after ovulation. The DF diameter (8.1 ± 1 mm) did not differ (P = 0.09) from SF diameter (7.6 ± 0.9 mm) at the time of follicular divergence (around 45 hours after follicular emergence). The DF and SF growth rates were similar (P > 0.05) until follicular divergence, at which point the SF growth rate decreased, whereas the DF growth rate remained constant. Serum E2concentrations did not change (P > 0.05) during the divergence period, whereas FSH concentrations decreased between 48 and 32 hours before follicular wave divergence. In conclusion, cows and heifers differed only in the interval from ovulation to follicular wave emergence and divergence, which was confirmed by the different patterns of FSH and E2concentrations.
authors.affiliation: Departamento de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Dorneles Tortorella
authors.affiliation: Departamento de Medicina Veterinária, Universidade Estadual Paulista, Araçatuba, SP, Brazil.
authors.forename: Guilherme de Paula
authors.initials: GP
authors.lastname: Nogueira
authors.affiliation: Departamento de Medicina Veterinária, Faculdades Integradas da União Educacional do Planalto, Gama, Distrito Federal, Brazil.
authors.forename: Mairon Rocha
authors.initials: MR
authors.lastname: Modesto
authors.affiliation: Departamento de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Priscilla Cristine
authors.initials: PC
authors.lastname: Passoni Silva
authors.affiliation: Departamento de Conservação de Recursos Genéticos Animais, Embrapa Recursos Genéticos e Biotecnologia, Brasília, Distrito Federal, Brazil.
authors.forename: Joseane Padilha
authors.initials: JP
authors.lastname: da Silva
authors.affiliation: Departamento de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Jairo Pereira
authors.initials: JP
authors.lastname: Neves
authors.affiliation: Departamento de Conservação de Recursos Genéticos Animais, Embrapa Recursos Genéticos e Biotecnologia, Brasília, Distrito Federal, Brazil. Electronic address: alexandre.floriani@embrapa.br.
authors.forename: Alexandre Floriani
authors.initials: AF
authors.lastname: Ramos
mesh_terms: D000222:Adaptation, Physiological; D000375:Aging; D000818:Animals; D002417:Cattle / Q000097:blood / Q000235:genetics / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006080:Ovarian Follicle / Q000502:physiology*; D014329:Tropical Climate
chemical_list: D004958:Estradiol; D005640:Follicle Stimulating Hormone
keywords: Conservation; Curraleiro Pé-Duro; Dominant follicle; Estradiol 17-β; FSH