Laparoscopic examination of the ovarian activity in alpacas

Ovarian follicular activity was determined in alpacas using the laparoscopy technique. Adult (> 3 years old) and young (11-18 months) females were observed during the breeding season (Feb.-Mar.) and the nonbreeding season (Aug.-Sep.) for a period of 36 days. Twenty adults and twenty young alpacas were divided into four groups of five each. Laparoscopic examination was done at 3, 5, 7 or 9-day intervals. Sexual receptivity was correlated to the number, position and size of antral follicles determined by laparoscopy. A three-way factorial design was used to detect differences between age, season and interval of observation. Chi-square analysis was used to observe differences in follicle growth between the left and right ovaries. There were no significant differences (P>0.05) in follicular activity with respect to age, season or interval of observation. Follicular growth took an average of 4 days (range 3-5 days) to reach ovulatory size (8-12 mm), which lasted an average of 4 days (range 2-8 days), with follicles subsequently undergoing atresia during a period of 4 days. In 85% of the cases, follicular growth alternated between the two ovaries, whereas in 15% the ovaries did not alternate in follicular activity. Females with follicles ≥ 6 mm adopted the copulatory position when tested by vasectomized males. Spontaneous ovulation was observed in 3.5% of the total number of large antral follicles recorded. Cystic follicles (>12mm) were detected in adult females only. Numerous follicles (≤ 4 mm) in one or both ovaries were observed on 13 occasions for a period of 2 weeks which was followed by resumption of activity by one of the ovaries. Significant follicle activity was present in both the breeding and nonbreeding seasons, with females being sexually receptive during both time frames. © 1989.