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 ≥7 mm was detected, llamas were assigned randomly to one of three groups and given 1 mg purified llama OIF/NGF im 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 24 hours 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 (P < 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. 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. Available from: https://www.researchgate.net/publication/264936903_The_effect_of_repeated_administrations_of_llama_ovulation-inducing_factor_OIFNGF_during_the_peri-ovulatory_period_on_corpus_luteum_development_and_function_in_llamas [accessed May 3, 2017].