Embryo transfer in alpacas is a worthwhile endeavor due to the advances it can bring to the fleece market.
In order to understand embryo transfer in alpacas, it is necessary to first understand the natural way in which alpacas become pregnant. Alpacas are induced ovulators and therefore have regular cycles of ovarian follicular growth. Follicle waves are made up of a number of follicles which all grow to 4-5mm in diameter. Once the follicles have grown to this size, one specific follicle will become the dominant in the group that will grow to 5-6mm while the other follicles undergo regression. If mating occurs, the dominant follicle will be released, as signaled by copulatory stimulus and ovulation-inducing factor in the male’s semen. Ovulation occurs around 30 hours post copulation and the corpus luteum will develop 2-3 days post ovulation. A decrease in blood concentration of progesterone must occur with 8 to 12 days post fertilization to ensure maternal recognition of the pregnancy. If the female is not exposed to males either through mating or close proximity, follicular waves will continue but the female will demonstrate long periods of receptivity. Receptivity is demonstrated through submission to a male for mating (Vaughan, n.d.).
The first breeding for a female should be once 65% of mature weight has been reached, typically by 12 months of age. However, follicle growth usually begins around 5-6 months of age. Receptive females are bred and then tested for receptivity around 7 days later. If the female is assessed as receptive, ovulation did not occur and the animal will be bred again. A receptive female at this point is then bred again and checked for receptivity 14 days later. A nonreceptive female indicates the presence of corpus luteum. Behavior testing is continued every 2 weeks throughout the first 60 days of pregnancy. Post 60days gestation, there is a five percent chance of fetal loss, therefore testing for receptivity is continued throughout the pregnancy at an interval of 2-4 wks. Ninety percent of females should conceive with this protocol; however the 10% that do not are not likely to be culled due to the breeder’s emphasis on the individual value of the animal (Vaughan, n.d.). Alpacas are generally accepted as less fertile than other livestock but the failure to cull animals that do not regularly become pregnant is most likely the explanation.
Embryo transfer in alpacas can occur through single ovulation or multiple ovulation methods. In the case of single ovulation, there are fewer requirements. Donor females are bred as to standard protocol but are then flushed 7 days post breeding. The receiving female then receives the embryo through transcervical implantation into the uterus. Pregnancy is assessed 25 days later by transrectal ultrasound. Multiple ovulation of a donor female is slightly more complicated. The donor female is made to superovulate by the application of hormones such as equine chorionic gonadotropin or follicle stimulating hormone. The donor female is then mated naturally and the embryos are flushed and collected after 7 days or post injection of gonadotropin-releasing hormone. The embryos are then loaded into an inseminating pipette and surgically transferred into the left uterine horn of a recipient female. In order for maximum success, the recipient female is synchronized by an injection of human chorionic gonadotropin (Hafez & Hafez, 2000; Vaughan, n.d.).
Embryo transfer has many benefits. Mainly, it is the practical way to speed up the improvement of genetics in alpacas. The generational interval in alpacas is very long compared to other livestock because alpacas are slow to reach sexual maturity and have a long gestation of 11.5 months. Therefore, conventional breeding results in slow genetic gain. The use of embryo transfer in alpacas increases the number of offspring that a superior female can have each year. Embryo transfer is beneficial to small breeders as there is a greater access to genetically superior genes. Also, a system that uses embryo transfer will see an increase in the number of animals that superior fleece, assuming selective breed was successful to achieving the goals set. Practical application of embryo transfer has been widely used and accepted in Australia, leading to a higher numbers of superior animals on a national scale. This translates directly into a greater amount of superior fleece harvested annually (Vaughan, n.d.).
Despite these merits, there is a lack of interest in fine-tuning protocols from embryo transfer in alpacas. This is primarily attributed to the young age that alpacas can be successfully bred and because nonpregnant alpacas remain receptive throughout the entirety of the year. Furthermore, the US Alpaca Registry does not allow for registration of alpacas as a product of embryo transfer or artificial insemination. The lack of national fiber market is possibly the reason that this technique is not pursued in the US. However, the benefits of embryo transfer are too great to be ignored by the US. The US should open the registry to embryo transfer offspring in order to keep up with global pace of alpaca genetic improvement (Pineda & Dooley, 2003; Safely & King, n.d.).
Hafez, B., & Hafez, E. S. (2000). Chapter 15- Llamas and Alpacas. Reproduction in farm animals (7th ed., pp. Pg 232-233). Philadelphia: Lippincott Williams & Wilkins.
Pineda, M. H., & Dooley, M. P. (2003). Reproductive Patterns of Alpacas. McDonald's veterinary endocrinology and reproduction (5th ed., p. Pg 540). Ames, Iowa: Iowa State Press.
Safely, M., & King, J. (n.d.). Alpacas as a Business. arilist. Retrieved January 23, 2012, from https://www.arilist.com/academy/about/business
Vaughan, J. (n.d.). Mating management and embryo transfer in alpacas. Australian Alpaca . Retrieved January 23, 2012, from nswhunter.alpaca.asn.au/notes/matingmanagementinembryotransfer.pdf