PARENT SESSION
OVARY - A

Monday, August 2, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(181) OVULATION INDUCING FACTOR IN SEMINAL PLASMA: SPECIES COMPARISON AND MOLECULAR WEIGHT DETERMINATION.

Ratto, Marcelo¹, Huanca, Wilfredo², Huanca, Teodosio², Singh, Jaswant¹, Adams, Gregg¹, ¹ Western College of Veterinary Medicine, Saskatoon, Saskatchewan² Faculty of Veterinary Medicine, Lima, Lima, Peru

ABSTRACT- Factors responsible for eliciting the ovulatory response in camelids (induced ovulators) are not well understood, but intramuscular administration of seminal plasma resulted in ovulation in non-mated llamas and camels suggesting the existence of an ovulation inducing factor (OIF). Two experiments were conducted to evaluate whether OIF is present in the seminal plasma of species other than Camelids, and to determine the molecular weight of the bioactive form in llama seminal plasma. In Experiment 1, ejaculates from llamas, alpacas, and bulls were centrifuged and seminal plasma was diluted with phosphate buffered saline (PBS) in a ratio 1:1. Mature female llamas were assigned randomly to treatment groups (n=19 per group) when a growing follicle ≥8 mm was detected by ultrasonography. Treatment consisted of a 2 ml im dose of seminal plasma of llama, alpaca and bull, or PBS (Control group). Ovaries were examined by ultrasonography 48 h and 7 days after treatment to detect and confirm ovulation. Ovulation rates differed (P<0.001) among the 4 groups (llama seminal plasma, 19/19; alpaca seminal plasma, 19/19; bull seminal plasma 5/19; PBS 0/19). In the Experiment 2, pooled seminal plasma from 4 llamas was diluted with PBS in a ratio of 1:1. A sample was transferred into centrifugal filter devices (Amicon Ultra-15) with nominal molecular weight cutoffs of 30,000, 10,000 and 5,000 daltons, and centrifuged at 4000 g for 40 minutes. Mature female llamas were assigned randomly to treatment groups (n=9 per group) when a growing follicle ≥8 mm was detected by ultrasonography. Treatment consisted of a 1.5 ml im dose of the 30,000 dalton, 10,000 dalton, 5,000 dalton, or ≤5,000 dalton fraction of seminal plasma. Positive and negative controls (n=9 per group) were treated with whole seminal plasma or PBS, respectively. Llamas were examined by ultrasonography 48 h and 7 days after treatment to detect and confirm ovulation. All llamas in the 30,000 dalton and positive control groups ovulated (9/9 in each), but none ovulated in any of the other groups (P<0.0001). In conclusion, OIF present in the seminal plasma is a well-conserved molecule in camelid species, and partly conserved in the bovine species. The bioactive form present in llama seminal plasma is a larger molecule (≥30,000 daltons) than that described in Bactrian camels.

KEY WORDS: ovulation inducing factor, camelids, seminal plasma