In vitro production of embryos in South American camelids

Semen Handling in South American Camelids: State of the Art

Reproductive biotechnologies such as artificial insemination could be very useful for South American camelids, allowing widespread use of semen from breeding males with desirable genetics. However, artificial insemination is not widely employed in these species and is considered to have low overall efficiency. This is due in part to incomplete knowledge about the physiology of conception in these species, and also to challenges presented by semen collection and handling. Several recent reviews have centered on female camelid reproduction; therefore, in this review, the focus is on semen handling. Various semen collection methods are presented. Different methods of reducing seminal viscosity are compared, such as needling, enzyme treatment, and colloid centrifugation. Use of enzymes remains controversial because of widely differing results among research groups. Colloid centrifugation, particularly single layer centrifugation, has proved to be successful in facilitating development of sperm handling techniques in dromedary camels, and has also been used with llama semen. Therefore, protocols for colloid centrifugation of alpaca semen could be developed in the future.

Effect of macromolecule supplement on nuclear and cytoplasmic maturation, cryosurvival and in vitro embryo development of dromedary camel oocytes

The current evaluation of oocyte vitro maturation (IVM) media has progressed toward more defined conditions in human and livestock. In this study, the replacement of fetal calf serum (FCS) with bovine serum albumin (BSA) and polyvinyl alcohol (PVA) was evaluated during IVM in dromedary camel. Nuclear maturation rates in presence of FCS and PVA were comparable (81.6 ± 1 and 75.5 ± 5%, respectively). BSA, whether used alone or in combination with FCS, significantly reduced nuclear maturation (51.6 ± 3.9 and 54.6 ± 1.1%, respectively), compared to FCS and PVA. BSA also increased the rates of chromosome aberrations compared to FCS and PVA (25.7 ± 7.4, 8.8 ± 2.3 and 6.0 ± 2.0%, respectively). IVM macromolecule differentially affected morphological aspects of cumulus expansion and FCS promoted the highest dissociation of cumulus cells, compared to all the other groups. FCS significantly increased mean lipid intensity of oocytes compared to BSA, FCS-BSA and PVA which could explain the lower cryo-survival of oocytes matured in presence of FCS compared to BSA and PVA (56.1 ± 5.2, 91.0 ± 19.5, and 87.8 ± 6.7%, respectively). Mitochondrial activity was not affected by macromolecules, but oocytes cultured with PVA had the best redox status, compared to other IVM groups. Cleavage was not affected by IVM macromolecule, but FCS promoted significantly higher rate of morula development (51.6 ± 5.2 vs. 33.6 ± 2.9% for PVA) and blastocyst development (36.8 ± 1.4 vs. 20.5 ± 2.0% for BSA). Although adding FCS during IVM supported highest hatching rate of the resulting blastocysts, differential cell number showed no long lasting effect of IVM macromolecules on blastocyst quality. Obtained results suggest the possibility to switch from undefined to more defined IVM systems for efficient in vitro maturation and subsequent vitrification of dromedary camel oocytes. Keywords: camel, oocyte maturation, protein supplement, cryosurvival.

Mapping of the Early Intrauterine Morphogenesis in the Alpaca (Vicugna pacos): External Features and Development of the Cephalic Vesicle in Comparison with the Progressive Carnegie Scale

In this study, we characterized the morphological aspects of the early development of the head of the alpaca (Vicugna pacos) and identified the main structures of the central nervous system during the first trimester of pregnancy. The topography and the cytoarchitecture of the fetal brain regions were described by histological analysis of the brain sections. We performed this analysis on alpaca embryos and fetuses presumably aged 20, 30, 45, and 90 days. For the description of the external body structures we considered the shape of the head, the development of the optic primordium, the dorsal curvature of the body, the limb buds, the umbilical cord and relative vessels, and the thickness and transparency of the skin. The prosencephalic, mesencephalic, and the rhomboencephalic vesicles were described by analyzing sagittal sections of the head. The present article provides the first progressive morphological and anatomical description of alpaca brain during early development. A detailed study represents an important basis to further understand the phases of prenatal development in this species, since information about alpaca embryology in incomplete and reproductive failure is a relevant factor. These data are important also for interspecies comparisons and application of reproductive biotechnologies. Anat Rec, 302:1226-1237, 2019. © 2018 Wiley Periodicals, Inc.

Effect of Extender and Freezing Rate on Quality Parameters and In Vitro Fertilization Capacity of Alpaca Spermatozoa Recovered from Cauda Epididymis

In alpacas, improvement of reproductive efficiency of male camelids is limited by the small testicular size, low spermatozoa production, and low quality of semen. In this study we aim to evaluate the effect of two extenders and two freezing rates on post-thaw quality of sperm recovered from alpaca epididymis with two methods (flushing and mincing), and to evaluate the in vitro fertilization (IVF) capacity of frozen sperm selected with two different selection methods (washing and swim-up). Sperm samples were processed with Tris-egg yolk or Bioxcell^® extenders and frozen with slow freezing and fast freezing. The oocytes were coincubated with spermatozoa for 72 hours, and cleavage rates were recorded afterward. The results indicated that the recovery method did not influence sperm quality (∼70%). However, total sperm recovery was significantly lower for the flushing method than the mincing method. The sperm quality was influenced by the freezing extender (23.3% vs. 33.2%) and freezing rate (20.9% vs. 35.7%). When comparing different methods of sperm selection for IVF, no differences were observed on cleavage rate except for the fact that the concentration of sperm from swim-up method (20.6%) was significantly lower than the one obtained from the washing method (78.7%). The recovery technique of sperm does not affect sperm quality and the method of fast freezing was shown to be the most effective for cryopreservation of alpaca sperm.

Production, Preservation, and Transfer of South American Camelid Embryos

The current review summarizes progress in the field of in vitro and in vivo production of South American Camelid embryos. Both methods require ovarian superstimulation (with FSH and eCG) to obtain multiple ovulations (in vivo embryo production) or to induce follicle growth for oocyte collection (in vitro embryo production). Moreover, superstimulation entails prior administration of hormones that inhibit follicular growth (progesterone, progestagens, and estrogens). Cumulus-oocyte complexes obtained must mature in vivo (buserelin administration) or in vitro to then be subjected to in vitro fertilization or intracytoplasmic sperm injection. All these techniques also require morphologically normal, motile spermatozoa to achieve fertilization. Methods used to decrease semen viscosity and to select the best spermatozoa (Percoll®; Androcoll-ETM) are described. Additionally, nuclear transfer or cloning has been applied in llamas. Up to now, embryo deep-freezing and vitrification have progressed slowly but are at the height of development. Embryos that are obtained by any of these techniques, either in vivo or in vitro, need to be transferred to synchronized recipient females. The best results are achieved after transfer to the left uterine horn with an ipsilateral ovulation. No live offspring have been obtained after the transfer of cryopreserved embryos. Applying reproductive biotechnologies, such as those described, will permit the expansion of genetically selected animals in the population and also that of wild camelid species, vicunas, and guanacos, whose embryos could then be transferred to the uterus of domestic species.

Semen collection methods in alpacas

South American camelids, particularly alpacas, are gaining in popularity outside their native lands. Reproductive biotechnologies, such as artificial insemination or embryo transfer with cryopreserved embryos, are more complicated in these species than many others due to differences in their reproductive physiology compared to the more commonly encountered domestic livestock. This article reviews the methods currently available for obtaining semen or spermatozoa from alpacas and describes some of the problems associated with handling the viscous seminal plasma characteristic of camelids. Possibilities and limitations of reproductive biotechnologies in this species are discussed, and future developments are outlined, especially some new techniques which are currently being developed for use with camel semen and may be transferable to alpacas.

Effect of oocyte maturation time, sperm selection method and oxygen tension on in vitro embryo development in alpacas

We evaluated the effect of in vitro maturation time, sperm selection and oxygen tension on alpaca embryo development. In Experiment I, Cumulus Oocyte- Complexes (COCs) were obtained from abattoir ovaries and in vitro matured in TCM-199 for 24 (n = 217), 28 (215), or 32 h (223) at 38.5 °C, high humidity and 5% CO₂ in air. Oocytes from 24 (n = 392), 28 (n = 456) or 32 (n = 368) h groups were in vitro fertilized with epididymal sperm and cultured in SOFaa at 38.5 °C, high humidity and 5% CO₂, 5% O₂ and 90% N₂ for 7 days. Embryo development was evaluated on Day 2, 5 and Day 7 of in vitro culture (Day 0 = in vitro fertilization). In Experiment II, a 2 by 2-factorial design was used to determine the effect of sperm selection (Swim-up vs Percoll) and oxygen tension (20% vs 5%) during embryo culture and their interaction on embryo development. COCs were in vitro matured for 32 h at 38.5 °C and 5% CO₂ in air and then in vitro inseminated with epididymal sperm processed by swim-up or Percoll. Zygotes were cultured in SOFaa + cumulus cells at 38.5 °C under 20 or 5% of O₂ tension and high humidity for 7 days. A total of 235, 235, 253 and 240 oocytes were assigned to: swim-up+20 O₂, swim-up+5 O₂ or Percoll+20 O₂, Percoll+5 O₂, groups respectively. The proportion of oocytes reaching MII stage was highest after 32 h of in vitro maturation (P < 0.05). Blastocyst rate (29.1 ± 2.7%) was also highest for COCs matured for 32 h (Exp I). In Experiment II, Blastocysts rate (26.03 ± 4.7; 27.7 ± 4.3; 29.7 ± 3.8 and 27.6 ± 4.2% for swim-up+20 O₂, swim-up+5 O₂ or Percoll+20 O₂, Percoll+5 O₂, respectively) was not affected by sperm selection method (P = 0.8), oxygen tension (P = 0.9) or their interaction (P = 0.5).