Effect of Two Cryopreservation Methods on Seminal Quality and Pregnancy Rate in Alpacas Induced to Ovulation with Seminal Plasma

Abstract

The objective was to evaluate the effect of two methods of freezing on seminal quality and effect of seminal plasma as an inducer of ovulation in pregnancy percentages in inseminated alpacas. The semen collection was made post copula. After the collection of the ejaculates, motility and volume were assessed. The ejaculates with volume (≥1 ml) and motility (≥ 60%) were mixed (pool), 80 % was used (3 samples/pool) and 20 % (2 samples/pool) during the experiment. Then and diluted in Tris-base with 20% egg yolk. The samples were cooled 1.5 hours at 5 °C. At that temperature it was combined with the basic dilutor plus glycerol, obtaining a final concentration of 5% glycerol, then they were packed in 0.5 mL (13 x 106 spem/straw) straws to be frozen by horizontal and vertical methods. The seminal (semen + vaginal fluid) quality analysis was performed fresh and after cooling and thawing. Insemination was performed in two groups with thawed semen from two straws of the vertical method, the first group 20 females induced to ovulate with GnRH analog, the second group 20 females induced to ovulate with seminal plasma. When comparing, the results obtained of motility, viability, HOST and acrosomal integrity of fresh sperm, after the freezing process, decreased (p<0.05) compared to fresh and refrigerated samples. On the other hand, when comparing the freezing methods, the sperm values frozen by the vertical method were higher than those obtained by the horizontal method, with (p<0.05) in motility and HOST without (p>0.05) in acrosomal integrity and viability. The vertical semen freezing method can replace the horizontal method to obtain pregnancy.

Pregnancy and birth rate outcomes in alpacas (Vicugna pacos) inseminated with frozen semen using two commercial extenders

“…No superiority was found in terms of sperm survival after freezing and thawing samples between the two commercial diluents tested (Biladyl® B: 51.2 ± 8.7% and AndroMed®: 45.8 ± 8.7%), and results were similar to the ones reported by García et al. (2020) applying the same technique used by the present study (eosin–nigrosine stain) with a range of viable sperm from 43.7% to 54.2%.…”

“…All the ejaculates evaluated in the present study had sperm characteristics within the normal ranges for the species and were similar to other studies in which alpaca semen was collected by artificial vagina (García et al., 2020; Santiani et al., 2005, 2013).…”

“…These results were slightly lower than those reported by García et al. (2020) in alpaca samples obtained by post‐coital aspiration and cryopreserved with a non‐commercial diluent using the vertical freezing method (46.3 ± 4.8%) and similar to the sperm motility values reported by the aforementioned authors using horizontal freezing (34.3 ± 1.7%). On the other hand, Vaughan et al.…”

“…Nevertheless, due to unsuccessful or low pregnancy rates when using SAC frozen sperm for AI (0%-31.6%) (Aisen et al, 2021;Aller et al, 2003;Bravo et al, 2000;Deza Calsin & Pacheco Curie, 2019;Fumuso et al, 2018;García et al, 2020;Ordoñez et al, 2013;Pacheco Curie et al, 2009;Stuart et al, 2019), this biotechnology is not widely used in SAC production and therefore remains limited to research centres.…”

“…attained byGarcía et al (2020) when AI was performed 26-30 h after induction of ovulation of female alpacas. Besides the difference in timing between induction of ovulation and moment of AI compared to our study (30-34 h post-induction), the mentioned authors also compared SP as a natural inductor of ovulation against F I G U R E 2 Percentages of alpaca viable sperm at different stages of sample processing (raw and frozen-thawed semen) using two commercial extenders (AndroMed® and Biladyl® B) (18 ejaculates, n = 8 males, replications = 2-3).…”