Ovarian Follicular Synchronization, Ovulation and Oocyte Development in Llamas and Alpacas

by Ratto, Marcelo

Abstract (Summary)
The purpose of the studies reported in this thesis was to increase our understanding of the reproductive physiology of South American camelids. Studies were conducted in llamas and alpacas to investigate methods to electively control ovarian follicular dynamics, to determine the effects of hormone preparations or biological factors derived from seminal plasma on ovulation induction, and to evaluate the establishment of superstimulatory protocols to induce a consistent ovarian follicular response for oocyte collection. The first study was designed to compare the efficacy of treatments intended to induce follicular wave synchronization among llamas, and to determine the effect of these treatments on pregnancy rates after fixed-time natural mating. In the first experiment, lutenizing hormone (LH) and follicular ablation treatments were most effective for inducing follicular wave synchronization, while estradiol plus progesterone (E/P) treatment was intermediate. In the second experiment, llamas were assigned randomly to Control, (E/P), and LH groups. A single, fixed-time natural mating was permitted 10 to 12 days after treatment. The pregnancy rate was higher (P<0.05) for synchronized llamas (LH and E/P groups combined) than for non-synchronized llamas (Control group). The second study was done to compare the effects of hormonal treatments and natural mating on ovulation induction, interval to ovulation, and luteal development in llamas. No differences were detected among groups (mated, LH, and GnRH) in ovulation rate (80%, 91%, 80%, respectively; P = 0.6), or interval from treatment to ovulation (30.0 ¡À 0.5, 29.3 ¡À 0.6, 29.3 ¡À 0.7 h, respectively; P = 0.9). Similarly, no differences were detected among groups (mated, LH, and GnRH) in maximum corpus luteum (CL) diameter. The third study documents the existence of an ovulation-inducing factor (OIF) in the seminal plasma of alpacas and llamas. In Experiment 1, female alpacas were given alpaca seminal plasma or saline intramuscularly (im) or by intrauterine infusion. Only alpacas that were given seminal plasma im ovulated. In Experiment 2, ovulation was detected in 9/10 (90%) llamas at a mean of 29.3 ¡À 0.7 hours after seminal plasma treatment. In Experiment 3, female llamas were given llama seminal plasma, GnRH, or saline im, 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 minutes and 75 minutes after treatment with GnRH and seminal plasma, respectively. Plasma LH remained elevated longer in the seminal plasma group (P < 0.05), and plasma progesterone concentration was twice as high in the seminal plasma group (P < 0.01). The fourth study describes the presence of an OIF in the seminal plasma of Bos taurus ¨C a species conventionally considered to ovulate spontaneously - contains OIF. Bull seminal plasma induced ovulations in 26% (5/19) of llamas compared to 0% (0/19) in PBS group (P < 0.001). The ovulation rate was lower (P < 0.01) in bull seminal plasma group compared to that in the groups treated with alpaca or llama seminal plasma (100%). The fifth study was conducted to determine a local versus systemic effect of ovulation-inducing factor in seminal plasma. Ovulation rate in the seminal plasma intramuscular group (93%) was higher (P < 0.01) than seminal plasma intrauterine group (41%), while the seminal plasma intrauterine curettage group was intermediate (67%). The sixth study was done to determine the time required for llama oocyte to reach the maturation stage, and to establish a superstimulatory treatment for oocyte collection. Llama oocytes reached second metaphase as early as 28 h after in vitro culture. The FSH- and eCG-treated groups did not differ (P = 0.85) with respect to the number of follicles ¡Ý6 mm at the time of cumulus-oocyte complex (COC) collection (17.9 ¡À 2.2 vs 17.7 ¡À 2.2), the number of COC collected (10.7 ¡À 2.1 vs 11.2 ¡À 2.3 per llama), or the collection rate per follicle aspirated (71 vs 74%). Finally, in the last study, the effect of two superstimulatory treatments was evaluated on ovarian response and COC collection efficiency and oocyte maturation in alpacas. No difference (P = 0.54) was observed between FSH and eCG- treated alpacas in the number of expanded (11.5 ¡À 2.9 vs 8.8 ¡À 2.8) or compact COC collected with ¡Ý3 layers of cumulus cells (12.5 ¡À 4.3 vs 14.3 ¡À 2.6; P = 0.72). No difference (P = 0.1) was detected between FSH and eCG groups in the number of expanded COC at first metaphase (1.2 ¡À 1.2 vs 1.7 ¡À 0.6) or second metaphase stage (8.5 ¡À 1.9 vs 6.0 ¡À 2.1) respectively. In conclusion, these studies demonstrated that the control of ovarian follicular wave emergence and ovulation induction in llamas will contribute consistently to the establishment of fixed-time natural or artificial insemination as well as recipient synchronization in embryo transfer programs. The discovery of an ovulatory molecule in the semen of this species generates a new area of research regarding the ovulation mechanism in induced ovulators. Characterization of this factor may have important implications in the diagnosis and treatment of male and female infertility. Finally, the superstimulatory treatments and oocyte development studies will establish the baseline for the development of an in vitro embryo production system in llamas and alpacas.
Bibliographical Information:

Advisor:Skidmore, Julian A. (Lulu); Singh, Baljit; Singh, Jaswant; Pierson, Roger A.; Roesler, William J.; Barth, Albert D.; Adams, Gregg P.

School:University of Saskatchewan

School Location:Canada - Saskatchewan

Source Type:Master's Thesis

Keywords:ovary ovulation ooctyes alpaca llama


Date of Publication:07/25/2005

© 2009 All Rights Reserved.