Sexual receptivity and time of ovulation in alpacas

Abstract

Using laparoscopy, different degrees of sexual receptivity and time of ovulation after single copulation were determined in alpacas. Sexual receptivity was assessed with intact males in 39 adults (? 3 years old) and 37 yearlings (12–14 months) and then laparoscopy was performed to correlate it with size of ovarian follicles. Time of ovulation was also determined at two different times after copulation. Females exhibited three degrees of sexual receptivity: immediate and slow acceptance, and refusal, with no difference between yearlings and mature animals ( P>0.05). Female alpacas bred over a wide range of follicle size with no differences between ages ( P0.05). Fifty percent of females ovulated at a normal time (30 h after copulation), 24% ovulated late (72 h), and ovulation was not observed in 26% of females. Forty percent of the animals that failed to ovulate were yearlings and 15% adults ( P<0.05). The average follicle size that ovulated was 8.1 mm, with 7 mm as the minimum size for ovulation, and with no association between follicle size and time of ovulation.