Characterization of the emergency and repetibility of the follicular wave in alpacas (Vicugna pacos)

Abstract

The study aimed to characterize the follicular emergence and determine the repeatability of the follicular wave in alpacas. For this, 34 female alpacas were selected and induced to ovulation by parenteral application of buserelin acetate (day 0). Two days after the hormonal stimulation, individual follicular development was recorded by counting the total number of antral follicles >3 mm in both ovaries. For this, an inter-daily transrectal ultrasound follow-up was done for 60 days. It was determined that the emergence of the follicular wave occurred on day 4.5 ± 1.4 (range 2-8). The number of antral follicles (NAF) >3 mm during three consecutive follicular emergencies was 2.8 ± 1.3 (range 1-8). Despite having a great similarity (p>0.05) in the NAF >3 mm during three successive follicular emergencies there is a significant difference in the average number of emerging follicles between alpacas (p<0.05). The repeatability of the NFA >3 mm in the three follicular waves was 0.72. The interval between waves was 16.9 ± 3.9 days (range 8-24) and was identified as variable among animals, which showed a repeatability of 0.23. It is concluded that the number of emerging follicles >3 mm represents a highly repeatable characteristic in alpacas, but variable among animals; the interval between waves was also variable and a non-repeatable character.