AETA Small Ruminant Ovum-Pick-Up Brief

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Published on: April 17, 2019

Submitted by Dr. Kevin Lindell

Recently, Dr. Rachael Gately, Tufts Veterinary Field Service, had the opportunity (through a collaborative research project) to explore the realm of small ruminant ovum pick-up (OPU)/in vitro fertilization (IVF).

We thought it would be interesting to the membership to relay our initial experiences and challenges.

To date, donors have been collected after superstimulation, using protocols somewhat similar to those we use in cattle. Without prior manipulation of the estrus cycle, a SR CIDR is placed on day −7. On day 0 donors receive PG and 1.5 cc of follicle-stimulating hormone (FSH) AM/PM; day 1 donors receive 1.0 cc of FSH AM/PM and then 1.0 cc of FSH on the morning of day 2. Oocyte collection is performed on day 4, resulting in a coasting period (time between the last FSH injection and time of collection) of approximately 48 hours. Variables such as FSH dosage, number of total injections, and coasting period seemed to make a significant impact on follicular recruitment, size, and competency, although the data set is very small to this point.

Oocyte collection is performed under general anesthesia using a short-needle system. A threaded small ruminant 18-ga OPU needle, attached directly to aspiration tubing (without using a metal rod) has been a relatively simple and successful method for oocyte collection, in conjunction with our regular aspiration/vacuum pump. Although we would ultimately like to offer small ruminant OPU as a purely laparoscopic procedure, it has been difficult to stabilize the ovaries well enough, so we have instead opted to externalize the ovaries briefly for aspiration.

As this procedure seems to be growing in interest amongst our clientele, we are looking forward to additional small ruminant oocyte collection trials and embryo development results.

The abstract below from a recent review article was also a useful tool as we initially organized equipment, consumables, and donor protocols.

Theriogenology (86) 2016

Recent advances in in vitro embryo production in small ruminants

By Maria-Teresa Paramio*, Dolors Izquierdo

ABSTRACT

To increase productivity in the small ruminant industry, the genetic material of these species should be improved. In vitro embryo production could be an important technology to reach this goal by combining selected male and female gametes. In the world, marketing of in vitro-produced embryos is an economical activity which is progressing rapidly in cattle but is practically nonexistent in small ruminants. Since the birth of the first lamb and kid using IVF in the 80s, several studies have been carried out; however, results still are inconsistent and unpredictable. Moreover, significantly fewer research groups are working on embryo production in small ruminants than in cattle and pigs. Although conventional methodologies of oocyte IVM, IVF, and IVC in small ruminants give rise to blastocysts, significant variation exists between experiments. One important reason for these differences is the heterogeneity of the pool of oocytes recovered from ovaries from slaughtered females. Oocyte quality, also referred to as competence, is the key factor in the success of in vitro embryo production programs. Different criteria are used to select the best oocytes for fertilization, such as follicle size, oocyte diameter and morphological appearance, and Brilliant Cresyl Blue staining. New research lines aimed at improving oocyte competence are: (1) arresting nuclear maturation in vitro allowing optimal capacitation of cytoplasm, (2) growing oocytes inside the follicle, and (3) identification of biomarkers of oocyte competence in granulosa and cumulus cells and metabolites in the follicular fluid.

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