title: The effect of repeated administrations of llama ovulation-inducing factor (OIF/NGF) during the peri-ovulatory period on corpus luteum development and function in llamas.
abstract: The objective of the study was to test the hypothesis that repeated administrations of OIF/NGF during the peri-ovulatory period (pre-ovulatory, ovulatory, early post-ovulatory), will enhance the luteotrophic effect in llamas. Female llamas were examined daily by transrectal ultrasonography in B- and Doppler-mode using a scanner equipped with a 7.5-MHz linear-array transducer to monitor ovarian follicle and luteal dynamics. When a growing follicle ≥7mm was detected, llamas were assigned randomly to one of the three groups and given 1mg of purified OIF/NGF im (intramuscular) (a) pre-ovulation (single dose; n=12), (b) pre-ovulation and at the time of ovulation (2 doses, n=10), or (c) pre-ovulation, at the time of ovulation, and 24h after ovulation (3 doses, n=10). The pre-ovulatory follicle diameter at the time of treatment, ovulation rate and the first day of CL detection did not differ (P=0.3) among groups. However, maximum CL diameter was greatest (P=0.003) in llamas in the 2-dose group, and smallest in the 3-dose group. Accordingly, the 2 dose-group had the largest day-to-day profile for CL diameter (P<0.01), area of CL vascularization (<0.01), and plasma progesterone concentration (P=0.01) compared to the other groups. Interestingly, the luteal response to 3-doses of OIF/NGF during the peri-ovulatory period was not different from a single dose. In conclusion, OIF/NGF isolated from llama seminal plasma is luteotrophic and the effect on CL size and function is affected by the number and timing of treatments during the peri-ovulatory period.
authors.affiliation: Department of Animal Science, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: A
authors.initials: A
authors.lastname: Fernández
authors.affiliation: Department of Animal Science, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Ulloa-Leal
authors.affiliation: Escuela de Medicina Veterinaria, Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Silva
authors.affiliation: Escuela de Medicina Veterinaria, Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Norambuena
authors.affiliation: Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada.
authors.forename: G P
authors.initials: GP
authors.lastname: Adams
authors.affiliation: Departamento de Histología y Anatomía, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Guerra
authors.affiliation: Department of Veterinary Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St. Kitts, West Indies. Electronic address: mratto@rossvet.edu.kn.
authors.forename: M H
authors.initials: MH
authors.lastname: Ratto
mesh_terms: D000818:Animals; D002161:Camelids, New World / Q000502:physiology*; D003338:Corpus Luteum / Q000187:drug effects*; D004334:Drug Administration Schedule; D005260:Female; D020932:Nerve Growth Factor / Q000008:administration & dosage / Q000494:pharmacology*; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology*
chemical_list: D020932:Nerve Growth Factor
keywords: Corpus luteum; Llamas; Nerve growth factor; Ovulation-inducing factor