Alpaca Breeding Technologies | Reproductive Evaluation in Alpacas for ET

Herd Evaluation: Is Your Farm Ready for an ET Program?

Jorge Reyna

BSc (Hons), MScVetSc (Sydney Univ.)

Lecturer in Higher Education - Learning Design

Faculty of Science

University of Technology Sydney

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Herd evaluation (HE) is a new concept developed by Alpaca Reproductive Technologies (ART) to ensure that animals destined for an ET program (donors and recipients) are suitable for the procedure, thereby optimising the production of quality embryos and pregnancies. Herd evaluation does not guarantee that females will respond to superovulatory treatments in the future, or that recipients will carry the pregnancy successfully and produce a cria. The idea is to discard “problem animals” which lead to less efficient results.

In my opinion, HE is essential prior to an ET program, due to the investment in hormones and laboratory materials and the time-consuming nature of the procedure. We need to make sure we are selecting females with the best chance of producing embryos (for donors) and of becoming pregnant (for recipients).

Herd evaluation takes into account 4 essential criteria in both donors and recipients:

· Rectal accessibility

· Morphology of the reproductive tract

· Ovarian examination

· Cervical accessibility

Rectal accessibility

Non-surgical ET and AI rely on access to the reproductive tract via the rectum. It is necessary to palpate the uterus and to locate the cervix and the uterine horns, both to perform the flushing procedure in donors and also to deposit the embryo or sperm into the recipient when AI is used. Without rectal palpation it is impossible to conduct these procedures. In cows, due to the size of the rectum, access to the reproductive tract via the rectum is possible in all cases. In the case of alpacas, there are some animals that are hard to get rectal access to. In my experience, 80% of animals are quite easy, 10% are more difficult and 10% are inaccessible via the rectum.

Rectal palpation in alpacas, when performed for the first time, needs to be very gentle. First you remove the faeces and then you place 30-50 ml of lubricant into the rectum. With a gloved, previously lubricated hand massage the entrance of the rectum, introducing finger after finger with circular movements until the sphincter relaxes and it is possible to introduce the whole hand (Figure 1). This procedure can take around 5 minutes or more in the case of animals with tight rectums. It is normal for there to be slight bleeding, as observed in cows. After the first rectal palpation, the animal will become easier to access in subsequent examinations.

In the case of animals with tight rectums, sometimes it is necessary to perform the procedure 2-3 times before getting access to the rectum. Sedation will help the animal relax the sphincter and make the procedure easier.

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Figure 1: Rectal palpation is an easy procedure but needs to be performed very gently and slowly for the first time. The animal is placed on an ET table in sternal recumbency. Note that the tail is raised and locked to facilitate access.

Morphology of the reproductive tract:

Upon introducing the hand into the rectum, the next step is to palpate the reproductive tract to ensure it is in perfect condition and does not present any anatomical abnormalities. In general terms, it is quite easy to find the reproductive tract, to follow the cervix and to locate the junction of the horns with the uterus. Following each horn, it is possible to palpate the ovaries as well (Figure 2). The most common congenital abnormalities in alpacas are uterus unicornis (one uterine horn) and uterine hypoplasia (infantilism). These abnormalities are easy to detect with rectal palpation. Abnormalities in the cervix configuration (irregular) are not possible to find by rectal palpation, but become evident when difficulty in penile penetration is observed. Pregnancy is possible in some cases, but breeding is not recommended because of the risk of genetic transmission of the trait.

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Figure 2: A normal reproductive tract from an adult female, showing (from right to left) vulva, vagina, cervix, uterus, horns and ovaries. This is the optimal morphology, which can be determined in most cases by rectal palpation.

Ovarian examination

Ovarian examination is possible to conduct by rectal palpation, but requires years of experience. Palpation it makes possible to differentiate between a corpus luteum and a follicle. The corpus luteum is a rigid structure which feels like a “small stone” that grows from the ovarian surface. In contrast, a follicle is a smooth structure. It is also possible to determine the size of the follicles by palpation, but again this requires a lot of practice. The most practical and accurate method is using transrectal ultrasound.

Using transrectal ultrasound in alpacas (TRUSA), it is possible to visualise the image of the alpaca ovary as a globular irregular shape which should present follicles in different stages of growth (Figure 3). Usually a dominant follicle from 4 to 9 mm is observed, along with smaller follicles. This may indicate that the animal has active ovaries which are presenting follicular waves. It is also possible to find persistent luteal activity (persistent luteinised follicles) by TRUSA. In this case females will have a high level of progesterone in the blood and reject the male. A treatment with prostaglandin will destroy the persistent follicle, making the female receptive again. If you find unovulatory follicles (>12 mm) (Figures 4 and 5), a treatment with GnRH will solve the problem.

In summary, donors and recipients should present with active ovaries, measured by the presence of a dominant follicle and/or small-medium size follicles. If pathologies, like persistent luteinised follicles or follicles larger than 12 mm, are found at the ovaries it is necessary to treat animals with hormones (prostaglandin, GnRH) before starting a superovulatory protocol (donors) and/or induction of ovulation (recipients).

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Figure 3: Alpaca ovary showing a dominant follicle (8 mm) and a small follicle on the right (3 mm)

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Figure 4: Alpaca ovary showing an unovulatory follicle (13 mm) observed by transrectal ultrasound.

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Figure 5: The follicle from Figure 4 observed by laparotomy.

Cervical accessibility

The alpaca cervix or uterine neck has been reported to be regular or irregular in shape with 2-3 rings, which is why some animals may not be suitable for ET or AI. We need to take into account that, to perform flushing of the embryos from the uterus, a Foley catheter needs to be passed across the cervix (Figure 6). In the case of AI, the deposit of the semen is done at the uterine horn which means that the insemination gun needs to pass the cervix as well. Regrettably, some of the animals present an irregular cervix which is very difficult to pass. These animals are not suitable for use as donors or recipients in an ET program.

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Figure 6: The right hand is inside the rectum palpating the reproductive tract while the left hand is very gently introducing the Foley catheter through the cervix. The insemination gun is placed onto the catheter to provide rigidity and to allow its introduction.

Finally, after HE is performed and the animals have passed the 4 essential criteria, you will know how many of them can be included in your ET program. You will thereby reduce the risk of including animals that are not worthy. It Is important to remember that animals need to be in good body condition and free of parasites/disease. After we perform HE on your farm, the next step will be to discuss your ET program according to your needs.

Please cite as:

Reyna, J (2006). Herd Evaluation. Is Your Farm Ready for an ET Program? The Camelid Quarterly Magazine, Canada. Vol 3, Sep. 47-48 p.

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