title: Comparison of antral and preantral ovarian follicle populations between Bos indicus and Bos indicus-taurus cows with high or low antral follicles counts.
abstract: The objective was to compare populations of antral and pre-antral ovarian follicles in Bos indicus and Bos indicus-taurus cows with high and low antral follicle counts. Nelore (Bos indicus, n = 20) and Nelore X Angus (1/2 Bos indicus-taurus, n = 20) cows were subjected to follicular aspiration without regard to the stage of their oestrous cycle (day of aspiration = D0) to remove all follicles ≥3 mm and induce growth of a new follicular wave. Ovaries were examined by ultrasonography on D4, D19, D34, D49 and D64, and antral follicles ≥3 mm were counted. Thereafter, cows were assigned to one of two groups: high or low antral follicular count (AFC, ≥30 and ≤15 antral follicles, respectively). After D64, ovaries were collected after slaughter and processed for histological evaluation. There was high repeatability in the numbers of antral follicles for all groups (range 0.77-0.96). The mean (±SD) numbers of antral follicles were 35 ± 9 (Bos indicus) and 38 ± 6 (Bos indicus-taurus) for the high AFC group and 10 ± 3 (Bos indicus) and 12 ± 2 (Bos indicus-taurus) follicles for the low AFC. The mean number of preantral follicles in the ovaries of Bos indicus-taurus cows with high AFC (116 226 ± 83 156 follicles) was greater (p < 0.05) than that of Bos indicus cows (63 032 ± 58 705 follicles) with high AFC. However, there was no significant correlation between numbers of antral and preantral follicles.
authors.affiliation: Laboratório de Reprodução Animal, DCV-CCA-Universidade Estadual de Londrina (UEL), Londrina, PR, Brazil.
authors.forename: K C
authors.initials: KC
authors.lastname: Silva-Santos
authors.forename: L S
authors.initials: LS
authors.lastname: Siloto
authors.forename: G M G
authors.initials: GM
authors.lastname: Santos
authors.forename: F
authors.initials: F
authors.lastname: Morotti
authors.forename: T N
authors.initials: TN
authors.lastname: Marcantonio
authors.forename: M M
authors.initials: MM
authors.lastname: Seneda
mesh_terms: D000818:Animals; D002417:Cattle; D030762:Estrous Cycle; D005260:Female; D006080:Ovarian Follicle / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D010053:Ovary / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D013045:Species Specificity; D014463:Ultrasonography