Nonsurgical embryo recovery and transfer in sheep and goats

Abstract

The embryo transfer techniques used in small ruminants worldwide are based in surgical procedures. These actions are performed under general anesthesia which needs a combination of animal fasting and drugs for secure animal handling and surgery manipulations. Therefore, it involves risks to animal health and life. The major limiting sequels are adhesions formed by the abdominal surgery, in the ovaries, uterus, or between them. These occurrences can both compromise uterus accessing and oocyte capture and are responsible for decreasing success and limiting successive embryo collections. In contrast, nonsurgical embryo procedures can be performed in a relatively simplified way. Nonsurgical embryo recovery does not need animal prolonged starvation, drug retention is minimized, and donors can stay in a standing position. After the end of embryo recovery, donors are promptly restored to their routine housing and feeding. Furthermore, this technique does not need incisions and, therefore, can be used repetitively in superovulated or nonsuperovulated goats and sheep for embryo recovery-a similar procedure done in cattle. In Brazil, promising results are reported using nonsurgical embryo transfer in recipient goats, and studies are currently evaluating similar procedures in sheep. Therefore, this review aimed to present the current panorama of nonsurgical embryo transfer in sheep and goats.

Combined treatment with oestradiol benzoate, d‐cloprostenol and oxytocin permits cervical dilation and nonsurgical embryo recovery in ewes

“…Approximately 20% of ewes in the breeding season may still require surgical procedures to recover embryos. As stated earlier, the consistency and repeatability of the “Embrapa protocol for cervical relaxation and uterine flushing” in other breeds of sheep ewes remains to be determined (Fonseca et al., ).…”

“…In vivo embryo production (IVP) continues to be the primary method to produce ovine embryos for commercial embryo transfer in Brazil. Surgical embryo recovery from donor ewes is the technique of choice worldwide, even though repeated invasive procedures may have severe adverse effects such as adhesions, postoperative trauma and stress (Candappa & Bartlewski, ; Fonseca et al., ). Nonsurgical (i.e., transcervical) embryo recovery is feasible and efficient, but this approach still needs to be refined and tested in different breeds of sheep (Candappa & Bartlewski, , ).…”

“…Despite cervical remodelling during the oestrous phase, cervical penetration for artificial insemination procedures in ewes remains problematic (Candappa & Bartlewski, ; Fonseca et al., ). Therefore, the use of 200‐400‐600 USP of exogenous OT was implemented to facilitate cervical dilation, which permitted complete cervical penetration in 74‐75‐83% of ewes, respectively, as opposed to 0% of saline‐treated animals (Khalifa, Sayre, & Lewis, ).…”

Assessing the usefulness of B‐mode and colour Doppler sonography, and measurements of circulating progesterone concentrations for determining ovarian responses in superovulated ewes

“…High variability in superovulatory outcomes is the major drawback of the MOET biotechnology in sheep; it has been attributed to several intrinsic and extrinsic factors (Bartlewski et al., ). Due to variable superovulatory responses and the fact that embryo collection in sheep is performed predominantly by a surgical technique (Fonseca et al., ), the ability to accurately and non‐invasively determine the outcome of hormonal superstimulation would be an invaluable asset.…”

“…extrinsic factors . Due to variable superovulatory responses and the fact that embryo collection in sheep is performed predominantly by a surgical technique (Fonseca et al, 2016), the ability to accurately and non-invasively determine the outcome of hormonal superstimulation would be an invaluable asset.…”