Want A Ram? No Problem. Want a Ewe? No Problem.
Reproduction Specialty Group Gives Producers Their Choice of Gender
Every producer has a preference. Many want ewes, because that’s where the long-term income potential tends to be. Some sell breeding stock and are happy with rams.
The one thing they have in common? Waiting anxiously for lambs to drop to see just what they’ll get. But it doesn’t have to be that way anymore. Reproduction Specialty Group of Indiana started providing gender sorting services to the American sheep industry in late 2018.
If your goal is to raise market animals for a specific show date or sales to a specific market, gender sorting can ensure you achieve it. If your goal is to produce as many daughters of a certain female family then gender sorting can ensure you achieve it. If you have a sire that produces higher quality males and/or females, you can now select specifically for that and eliminate the less desirable gender when using sorted semen.
Gender sorting has been used in the cattle industry – especially with dairy cattle – for a long time. Turns out, the technology behind gender sorting isn’t all the different for sheep and goats. Sexing Technologies of Navasota, Texas, holds the original patent on the process and has licensed RTI International to develop the process for sheep and goats around the world.
“We’ve partnered with RTI to provide those services here in the United States,” says RSG Founder Dr. Tad Thompson. “We run 1,000 commercial ewes, so we’ve been able to use those as our research animals instead of trying to work with an individual producer. The challenge of working with producers is that in setting up a true, scientific study, a producer has to be willing to make some sacrifices for the sake of science. That might set them back two or three breeding cycles, and that would have a huge impact on a commercial producer.”
While the general technology was already in place, there were some issues to sort out when transitioning the process from cattle to sheep.
“One of the big changes is the number of cells per breeding,” Thompson says. “In general, sheep and goats aren’t as reproductively efficient as cattle. So, they require higher cell counts to achieve the same pregnancy rates as cattle. For example, cattle will use somewhere between two to four million cells per insemination. We’re actually using eight million cells per insemination in sheep. That’s been one of the challenges as we spent the last couple of years preparing to introduce this technology to the small ruminant industry. Of course, there’s a tremendous amount of research going on in small ruminants in Australia and New Zealand. Their research trials include thousands of head, as opposed to hundreds of head here in the United States.”
This technology takes a raw ejaculate from a ram and separates the natural distribution of 50/50 male/female sperm cells into individual subpopulations of X Bearing and Y Bearing sperm. The dam (XX) will always contribute one of her two X chromosomes to her offspring. The sire (XY) however, will donate either a Y chromosome or an X chromosome, resulting in the offspring being male or female respectively.
The gender sorting machine was designed to separate the semen into individual subpopulations of cells containing either X chromosome-bearing cells (female) or Y chromosome-bearing cells (male) based on the size difference between the two chromosomes. Since the X chromosome is larger and contains slightly more genetic material than do Y chromosomes, they can be differentiated based on intensity of signals when the laser illuminates them.
The process involves putting semen into a media that contains a viable fluorescent dye that is attracted to genetic material. The more genetic material a cell contains, the more dye it absorbs. X chromosome-bearing cells absorb more dye than do Y chromosome-bearing cells. The semen is then run through a flow cytometer where the sperm pass single file in front of a laser. The laser Illuminates each cell and, because of the viable dye, causes them to fluoresce. The amount of fluorescence determines whether the cell is carrying an X or Y chromosome.
The sorting machines fluidic jet produces between 60,000 and 70,000 droplets per second and applies a slight electric charge to each droplet containing the desired sperm cell based on the chromosome it is carrying. As the cells exit the machine they pass between two differently charged field plates. The charge on the droplets that contain the sperm of interest reacts to these differently charged plates – one negative, one positive – which directs the droplets into the gender-appropriate vials.
This sorting technology allows for immediate fresh use or frozen for future use. Using gender-sorted semen will give producers the opportunity to ensure 90 percent, on average, of their lambs being born in a specific window will be the gender they are hoping to achieve.
“There are applications for it across a lot of different breeds and sectors of the industry,” Thompson says. “I think we’ll see the most acceptance early on within the show lamb industry. There are more people there already involved in using artificial insemination, embryo transfer and frozen semen. Since they are already involved in that technology, they’ll be more likely to take the next step to gender selection. I think there’s also opportunity with some of the heritage breeds because of their limited numbers. They could benefit from selecting for the females.”
In time, Thompson believes the commercial industry will also enjoy the benefits of gender selection. Large producers might never implement the technology in an entire flock, but could benefit from using it on a small scale.
“It’s not for everyone, but it’s another tool in the toolbox for the American sheep industry,” Thompson said.
To learn more, visit ReproSpecialty.us.
Meet RSG Founder Dr. Tad Thompson
Dr. Tad Thompson grew up with purebred Angus cattle on his dad’s farm in central Illinois. His family relocated to Indiana when he was 5 years old, and his path into the sheep industry began when he started 4-H and got his first Suffolk ewe.
In the early 1990s, Thompson was exposed to Laparoscopic Artificial Insemination when Purdue University hosted an LAI date for Dr. Dennis Gourley. Thompson was in high school and running a group of 50 purebred Suffolk ewes and active in FFA. He went on to attend Purdue University and graduated in 1998 with a bachelor’s in agriculture economics. He took a job with John Deere, working in the parts department of a local dealer, but quickly decided that working inside an office every day was not what he wanted for the future.
Thompson married Amanda Lamb – yes her maiden name was Lamb – in 1999 and started the process of applying to veterinary school. He graduated from Purdue School of Veterinary Medicine, having spent all his extra time in school working on learning the LAI and embryo transfer processes. One of the most influential pieces of his time in school came in the spring of 2006. Thompson spent two months working for AllStock Genetics – a pioneer of LAI and ET work in Australia. Working every day with Dr. David Osborn and his crew was the best education possible for a veterinarian learning these processes.
Upon coming home from Australia and graduating from Purdue, Thompson pursued a year-long internship at Equine Services in Simpsonville, Ky. When that year was done, the family moved to Janssen Veterinary Clinic in Sheridan, Ind. Thompson split his time there between equine work and the growing business of small ruminant reproduction. In 2008, Thompson built the company’s first facility for embryo surgery.
In July of 2012, Thompson and his family decided that the small ruminant world was where their hearts really were and Reproductive Specialty Group was born. RSG is the realization of a dream that began a long time ago when a high school student watched a sheep being bred and said, “I want to do that someday.”