title: Effect of purified llama ovulation-inducing factor (OIF) on ovarian function in cattle.
abstract: Two experiments were designed to determine the effect of purified ovulation inducing factor (OIF) on ovarian function in cattle. In Experiment 1, prepubertal heifers (n = 11 per group) were treated on Day 5 (Day 0 = day of follicular wave emergence) of the follicular wave with an intramuscular dose of saline (1 mL), GnRH (100 μg), or purified OIF (1 mg/100 kg body weight). Ovulation occurred in 9/11 heifers treated with GnRH, and 1/11 heifers in each of the OIF- and saline-treated groups (P < 0.05). Compared to saline-treated controls, OIF treatment was associated with a smaller dominant follicle diameter (P < 0.01), a rise in plasma FSH concentration (P < 0.1), and earlier emergence of the next follicular wave (P < 0.05). In Experiment 2, sexually mature heifers were given either GnRH or purified OIF on Days 3, 6 or 9 of the first follicular wave (i.e., early growing, early static, or late static phase of the dominant follicle; n = 5 per group per day), or were untreated (n = 10). In heifers treated with OIF on Day 6, the dominant follicle diameter profile tended to be smaller than in controls, and was associated with a rise (P < 0.05) in plasma FSH concentrations. A similar rise in FSH was detected after OIF treatment on Day 9. Compared to untreated controls, treatment with OIF and GnRH was associated with a larger CL diameter (Days 3 and 6 groups; P < 0.05) and a greater concentration of plasma progesterone (Days 6 and 9 groups; P < 0.05). Treatment with purified OIF did not induce ovulation in heifers, but hastened new follicular wave emergence in prepubertal heifers, influenced follicular dynamics in a phase-specific manner in mature heifers, and was luteotrophic.
authors: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tennessee, USA.
authors: V M
authors: VM
authors: Tanco
authors: M D
authors: MD
authors: Van Steelandt
authors: M H
authors: MH
authors: Ratto
authors: G P
authors: GP
authors: Adams
mesh_terms: D000818:Animals; D002161:Camelids, New World / Q000378:metabolism*; D002417:Cattle / Q000097:blood / Q000502:physiology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone / Q000378:metabolism; D010053:Ovary / Q000187:drug effects*; D012741:Sexual Maturation; D013045:Species Specificity
chemical_list: D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone