New frontiers - Embryo transplant, laparoscopic AI performed in sheepWritten by Wilson Stewart
Casper – Both embryo transplant (ET) and artificial insemination (AI) have been used for an extensive amount of time by producers in the cattle industry. However, sheep producers have only more recently been able to take advantage of this wonderful technology in their flocks.
In fact, according to Jim Dona of Dona Livestock, “To my knowledge, in Wyoming, embryo transplant has only been done on a research based situation at the University of Wyoming. This is the first time a producer has flushed ewes in the State of Wyoming.”
This August, club lamb operations run by Dona, Heath Hornecker and Jack Stewart, as well as the Casper College Ag Department, worked together to collectivity breed approximately 40 ewes via both ET and AI, enlisting the advice and technical expertise of Glen Erickson, who performed both the procedures on site at the Stewart’s property.
Bringing in an expert
Erickson is a graduate of Utah State University.
“I have a B.S. degree, in animal science from Utah State. I also have a masters degree in reproduction from Utah State,” he said.
According to Erickson, “I have been doing this for 25 years and on my own for eight years.”
In that time, he has performed ET on sheep, goats and whitetail deer in 48 states.
He adds, “I even bred a yak once.
Erickson explained briefly that AI in sheep is different from cattle. While cattle are AI’ed vaginally, sheep cannot be, due to their reproductive anatomy.
“In a cow’s cervix, there are three rings, all lined up in the center,” he continued. “The sheep cervix anatomy is so different. It’s very soft. There are seven cervical rings like a funnel, with the small end towards us. They’re offset.”
According to Erickson, University of Guelph in Ontario, Canada developed a method to breed sheep through the cervix. However, this apparently caused many injuries to the ewes.
He also stated, “Conception rates with the Guelph method were pretty low.”
The method used to artificially inseminate sheep now is known as laparoscopic (LAP) AI.
Erickson explained, “Just below the ewe’s udder, we make two incisions. Through one side we look through a laparoscope, locate and identify the uterine horns. Through the other hole we put the breeding tip in, right into the uterine horn and deposit semen.”
Erickson later explained that using this method, roughly 20,000 percent more sperm is deposited in the uterine horn than during natural breeding.
Prior to AI
Before ET or AI can take place however, a complicated and strict regimen, recommended by Erickson, is instituted on all the ewes involved.
Stewart of Stewart Club Lambs explained, “We went into a feeding and drug regimen that was suggested by Mr. Erickson. This included giving numerous injections and feeding only grass hay.”
The preparation took place prior to two days of ET and AI.
On Aug. 22, the first actual day of procedures took place. With the help of several Casper College ag students, as well as Dona, Hornecker, Stewart and others, Erickson AI’ed 10 ewes using the laparoscopic method. Six of these ewes would later be used for donor ewes for the ET program.
A total of five different rams’ semen was used in the process, either from frozen straws or freshly collected.
Six days later, on Aug. 28, embryos were transplanted into ewes.
During this process, the donor ewes were flushed with fluid to extract the six-day-old embryos within their uteruses. As a whole, 60 viable embryos were extracted from all the ewes used, which is above the average.
Dona commented, “We were certainly pleased with our embryo production.”
These embryos were then implanted in 30 donor ewes, which should produce approximately 42 lambs, based on averages provided by Erickson.
Reasons for new procedures
Dona and Stewart, who often partner in their lamb enterprises, had similar reasons for doing ET.
Dona explained, “It’s going to allow me to choose a select group of females that are bred the same, that are out of my best ewes and do it in one year, versus three or four.”
Stewart added, “Basically we are leveraging our genetics through the ewe base, rather than the ram base.”
With his partnership with Casper College, Hornecker comes at a different angle.
“It’s a new technology. From the college perspective, we were hoping to learn the process,” he said. “Hopefully we can teach other producers about this in the future.”
By and large, all involved recognize that the process is on its way to becoming the future of the lamb business as the ability to see a single ewe’s bloodline extended years ahead, in a single year, is invaluable.
As with any major capital investment operation, there are some risks involved.
Hornecker noted, “Well, there’s a financial risk. It’s not a cheap process.”
Dona and Stewart agreed.
Dona also added, “We could only get a few eggs from the donors. We were fortunate and averaged 10 eggs per donor ewe.”
There are also health risks. Stewart said, “It’s risky for the ewes when we chemically and hormonally treat these ewes so heavily.”
Hornecker added, “It is an invasive surgery.”
Despite the risks, the producers expressed interest in pursuing the technology into the future.
Hornecker said, “It was a success for us, even at this point. Being able to get the students involved and see that type of technology was an awesome experience for them.”
Stewart’s plan is focused more long term, and he said, “We want to give this at least two years.”
Dona added, “I see this growing for Dona Livestock. I think the future of the flock is very bright. After talking to others who do ET, it pays for itself pretty quickly. It puts our program ahead at a faster pace.”
Before performing embryo transfer or artificial insemination, selecting ewes is an important step.
In choosing which ewes to flush, Jack Stewart of Stewart Club Lambs said, “The donors that we chose were based on their performance and also their genetics. They were ewes that had performed well in the past.”
Jim Dona of Dona Livestock echoed his reasoning.
Aside from donor ewes, recipient ewes must be carefully chosen. While any ewe could be used as a surrogate mother, discretion should be used to encourage better results.
Heath Hornecker explained, “We searched for ewes that had lambed and were of the right age to become a recipient mother.”
Stewart further explained, “White-face ewes tended to be better recipient ewes than black faces, particularly if they had some Dorset in them.”