164 Embryo Survival to Calving According to Type of Embryo and Embryo Transfer Method in Alpacas

Abstract

The objective of the study was to determine the embryo survival up to calving of fresh and cryopreserved (frozen and vitrified) alpaca embryos transferred into alpaca recipients by nonsurgical transcervical embryo transfer and by surgical laparoscopically aided embryo transfer. For this report we have compiled the information from 127 embryo transfers in alpacas done by our group at Mallkini, Puno, Peru, at 4200 m elevation. The embryos have been collected from superovulated donor alpacas flushed at 6.5 days post mating, some were transferred as fresh and some were cryopreserved; the recipients (3 to 7 years old) were selected based on presence of functional corpora lutea at ecosonographic examination and subjected to ovarian cycle synchronization and ovulation induction as per Vivanco (2013). From a total of 133 alpacas selected, 127 were used, from which 82 received fresh, 32 frozen, and 13 vitrified embryos. All embryos were classed as A-class expanded blastocysts at time of transfer. By nonsurgical transcervical embryo transfer, 33 embryos were transferred fresh, 22 were frozen/thawed embryos, and 13 were vitrified/warmed embryos. By surgical laparoscopically aided method, 49 embryos were transferred fresh and 10 embryos were frozen/thawed; no vitrified embryos were transferred by this method. Results are detailed in Table 1. Pregnancy losses occured at up to 9 weeks (63 days) of gestation, the heaviest loss occurs in the first 3 weeks. After 9 weeks of gestation, no losses were registered. In average, 22% of fresh embryos transferred were represented as crias born. None of the cryopreserved embryos survived up to 11 weeks post-transfer. There is no difference in percentage of crias born between nonsurgical transcervical embryo transfers and surgical laparoscopically aided embryo transfers.The heavy embryo losses could be related to nutrition and high-altitude limitations; however, it is difficult to make comparisons with others because reports to date lack information on the actual crias born from embryo transfers in alpacas; most of the reports are based on pregnancy reports up to 30 to 60 days post-transfers. To date, no births from cryopreserved alpaca embryos have been reported. Furher studies on causes of embryo/fetal losses are necessary. Table 1.Results of embryo transfer This study was financed by the Peruvian Fund for Innovation, Science and Technology (FINCYT).

Birth of a Live Cria After Transfer of a Vitrified-Warmed Alpaca (Vicugna pacos) Preimplantation Embryo

“…We believe that this low-stress environment may have enabled not only establishment of the pregnancy but also maintenance of the pregnancy to term. Previous work by several members of this same research team ( 10 , 11 ) had resulted in several pregnancies with cryopreserved alpaca embryos; however, all pregnancies were lost within the first 4 months of gestation. Pregnancy loss in extensively managed alpacas is quite common and can range from 50 to 70% ( 29 ).…”

“…To the authors' knowledge, this birth represents the world's first cria produced after the transfer of a cryopreserved alpaca embryo. Preimplantation embryos recovered non-surgically from the uterus of alpaca donor females typically are hatched blastocysts > 400 µm in diameter (8), and this relatively large size poses a significant challenge to adequate removal of osmotically free water from the embryonic cells during the cryopreservation process. The high lipid content of alpaca embryos (7) also makes it difficult to achieve adequate embryo dehydration because the heads of phospholipids are hydrophilic.…”

“…Of special note with respect to embryo transfer technology is the difficulty in cryopreserving alpaca embryos (5) using either slow cooling or vitrification methods (6). Possible reasons for the difficulty in cryopreserving alpaca preimplantation embryos include the high lipid content of cells comprising the embryo (7) and the large number of cells present when embryos enter the uterus as hatched blastocysts (8). This challenge with cryopreservation of large diameter embryos is not unique to alpacas, as large diameter equine blastocysts have proven challenging to cryopreserve, especially using slow cooling techniques (9).…”

“…Pregnancies have been reported from the transfer of alpaca preimplantation embryos cryopreserved via slow cooling ( 10 , 11 ) or vitrification ( 10 ). However, no live births were reported from those studies.…”