Ovulation-Inducing Factor in the Seminal Plasma of Alpacas and Llamas

• Published in: Biology of reproduction Vol. 73; no. 3; pp. 452 - 457
• Main Authors: ADAMS, Gregg P, RATTO, Marcelo H, HUANCA, Wilfredo, SINGH, Jaswant
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.09.2005
• Subjects: Animals; Biological and medical sciences; Camelids, New World - physiology; Female; Fundamental and applied biological sciences. Psychology; Gonadotropin-Releasing Hormone - pharmacology; Luteinizing Hormone - physiology; Male; Mammalian male genital system; Morphology. Physiology; Ovulation - drug effects; Ovulation - physiology; Progesterone - blood; Semen - chemistry; Semen - physiology; Vertebrates: reproduction; ovulation-inducing factor; Semen; corpus luteum function; Gonadotropin RH; Ovulation; Hypothalamic hormone; camelids; Ovary; gonadotropin-releasing hormone; Reproduction; Adenohypophyseal hormone; Female genital system; Corpus luteum; Luteinizing hormone; Seminal plasma; Hormone releasing factor
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.105.040097

Studies were conducted to document the existence of an ovulation-inducing factor in the seminal plasma of alpacas (experiment 1) and llamas (experiment 2) and to determine if the effect is mediated via the pituitary (experiment 3). In experiment 1, female alpacas (n = 14 per group) were given alpaca seminal plasma or saline intramuscularly or by intrauterine infusion. Only alpacas that were given seminal plasma i.m. ovulated (13/ 14, 93%; P < 0.01). In experiment 2, ovulation was detected in 9/10 (90%) llamas at a mean of 29.3 ± 0.7 h after seminal plasma treatment. Plasma progesterone concentrations were maximal by Day 9 and were at nadir by Day 12 posttreatment. In experiment 3, female llamas were given llama seminal plasma, GnRH, or saline i.m., and ovulation was detected in 6/6, 5/ 6, and 0/6 llamas, respectively ( P < 0.001). Treatment was followed by a surge ( P < 0.01) in plasma LH concentration beginning 15 min and 75 min after treatment with GnRH and seminal plasma, respectively. Plasma LH remained elevated longer in the seminal plasma group ( P < 0.05) and had not yet declined to pretreatment levels after 8 h. Compared with the GnRH group, corpus luteum tended to grow longer and to a greater diameter ( P = 0.1) and plasma progesterone concentration was twice as high in the seminal plasma group ( P < 0.01). Results document the existence of a potent factor in the seminal plasma of alpacas and llamas that elicited a surge in circulating concentrations of LH and induced an ovulatory and luteotropic response. Abstract A potent factor in the seminal plasma of alpacas and llamas elicits a surge in circulating concentrations of LH, and induces ovulatory and luteotropic responses