title: Preovulatory follicle diameter, growth rate and time of ovulation during induced oestrus using a CIDR® in trypanotolerant female Bos taurus N'Dama cattle.
abstract: The aim of this study was to assess the dose (300 to 600 IU) effects of equine chorionic gonadotropin (eCG) on the preovulatory follicle diameter, growth rate and time of ovulation characterized by echography. The eCG was injected at the end (D0) of the 7-day treatment with a controlled internal device release (CIDR®) and a PGF2α being injected 2 days before the removal of the CIDR® (d-2). The 120 N'Dama female were distributed into five experimental groups. The control group (n = 26) was treated with physiological saline at the removal of the CIDR®, while the animals in the four treated groups received, respectively, 300 IU (n = 25), 400 IU (n = 24), 500 IU (n = 22) and 600 IU (n = 23) of eCG. The diameter of the preovulatory follicle was significantly higher (P < 0.05) in the animals treated with 300 IU (10.1 ± 1.4 mm) than in untreated animals (9.3 ± 1.2 mm). Follicle growth rate was significantly (P < 0.05) higher in treated animals (1.0 ± 0.4 mm/day) than in the control group (0.9 ± 0.4 mm/day). The average interval between the time of eCG injection and ovulation was similar in the non-treated (83.7 ± 14.4 h) and treated animals (79.7 ± 11.9). Treated animals showed a significant increase in the percentage of ovulation (94.7 % compared to 73.1 %) (P < 0.01). Use of eCG contributed towards synchronising the time of ovulation between 72 to 96 h, which would facilitate the use of systematic insemination.
authors.affiliation: Faculty of Veterinary Medicine, Theriogenology of Animal Production Department, University of Liège, Avenue de Cureghem, 7d, 4000, Liège, Belgium.
authors.forename: M'foumou W'otari Marcel
authors.initials: MW
authors.lastname: Okouyi
authors.affiliation: Faculty of Medicine, University of Liège, CHU-Tour de Pathologie-B 23 Sart Tilman, 4000, Liège, Belgium.
authors.forename: Pierre-Vincent
authors.initials: PV
authors.lastname: Drion
authors.affiliation: Faculty of Veterinary Medicine, Theriogenology of Animal Production Department, University of Liège, Avenue de Cureghem, 7d, 4000, Liège, Belgium. christian.hanzen@ulg.ac.be.
authors.forename: Christian
authors.initials: C
authors.lastname: Hanzen
mesh_terms: D000818:Animals; D002417:Cattle; D015237:Dinoprost / Q000008:administration & dosage; D004971:Estrus / Q000187:drug effects*; D005260:Female; D006064:Gonadotropins, Equine / Q000008:administration & dosage*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000187:drug effects*; D010060:Ovulation / Q000187:drug effects; D010062:Ovulation Induction / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D011374:Progesterone / Q000008:administration & dosage; D014463:Ultrasonography
chemical_list: D006064:Gonadotropins, Equine; D011374:Progesterone; D015237:Dinoprost
keywords: CIDR; Follicular growth; N’Dama cow; Ovulation; eCG