Short Communication. Embryo yield in llamas synchronized with two different intravaginal progesterone-releasing devices and superovulated with eCG

Abstract

The objectives of this study were to compare the effects of two intravaginal devices (ID) containing the same dose (0.5 g) of progesterone (P 4 ) on subsequent ovarian response, embryo production and circulating P 4 concentration profile in llamas (Lama glama) treated with equine chorionic gonadotropin (eCG) for ovarian superstimulation. Female llamas were randomly assigned (n = 10 llamas per group) to one of the following groups and treated (Day 0) with an ID containing 0.5 g of vegetal P 4 to synchronize the emergence of a new follicular wave: i) DIB 0.5 ® and ii) Cronipres M15 ® . On Day 3 llamas were intramuscularly treated with 1000 IU of eCG. The IDs were removed on Day 7. Llamas were naturally mated (Day 9) and treated with GnRH analogue to induce ovulation. A second mating was allowed 24 h later. Embryos were collected between 7 and 8 days after the first mating. Blood samples were taken every day from Day 0 to Day 7 to measure circulating P 4 concentrations. The results indicated that DIB device maintained greater plasma P 4 levels as compared to Cronipres until Day 2. However, the mean (± SD) number of corpora lutea and recovered embryos was not affected (p < 0.05) by the type of ID (5.3 ± 2.6 vs 4.2 ± 2.2 and 3.5 ± 2.7 vs 2.6 ± 3.0 for DIB and Cronipres, respectively). In conclusion, both DIB and Cronipres devices can be successfully used to synchronize the emergence of follicular wave prior to a single dose of eCG in superovulation protocol in llamas.Additional key words: South American camelids; superovulation; hormonal treatment; embryo.

Hormonal changes and follicular activity after treatment with intravaginal progesterone‐releasing devices in llamas

“…Besides, Aller et al. () proved in superovulated llamas that all animals were sexually receptive by day 2 after the end of P 4 treatment, although no description of follicular development was reported in this study. Meanwhile, there are no studies characterizing plasma P 4 concentrations and their effects on follicular activity in llamas treated with IVDs containing lower or higher P 4 concentrations than those previously evaluated.…”

“…However, after CIDR ® insertion, concentrations sharply decreased until day 3 after insertion, while the device containing 780 mg in the present study maintain concentrations around maximum until device withdrawal. Besides different P 4 contents in the devices, it has been suggested in llamas (Aller et al., ) and cows (van Werven et al., ) that differences in contact surface area between devices result in different P 4 plasma concentrations patterns. It could be speculated that in the present study, differences between devices hormone release may partly be responsible for the observed patterns.…”

Administration of progesterone BioRelease LA inhibits follicular growth in llamas (Lama glama) regardless of follicle diameter at the start of treatment

“…The plasma concentration rapidly decreased until Day 3 of treatment and then decreased slowly, until reaching basal levels. Aller et al (2015) obtained this same pattern of circulating progesterone using two different intravaginal devices containing the same dose (500 mg). Besides, the results of the present study showed that the treatment of 150 mg of Progesterone BioRelease ® LA was more efficient in inhibiting the ovarian follicular dynamics and it was observed follicular growth by Day 7 and 8 and an ovulatory size follicle at the end of the treatment (Day 10).…”