New Advances in Reproductive Technology
FORT COLLINS, COLO. (Dec. 3, 2008) — Most so-called “new” reproductive technologies stem from decades-old concepts and many years of research. According to Colorado State University reproductive physiologist George Seidel, technologies like sexed semen, cloning and transgenics seem new because of their recent application by the beef cattle industry. During the Robert E. Taylor Memorial Symposium in Fort Collins, Seidel provided a review of some of the newer technologies, commenting on their potential.
Sexed semen. The subject of more than 50 years of serious research, recent years have seen development of a practical technique for sorting sperm cells so the gender of a calf can be predetermined through artificial insemination with sexed semen. The accuracy with which sperm cells can be sorted approaches 90%. Most large bull studs in the U.S. now offer sexed semen, but beef producer interest pales in comparison to the dairy industry.
CSU reproductive physiologist George Seidel discussed application of newer technologies, such as sexed semen, cloning and transgenics.
“Still, it’s an imperfect product,” Seidel stated. “The fertility is lower than unsexed semen, and it is available from a limited number of sires. It’s also more expensive, currently costing about $25 more per straw.”
Seidel said he sees the use of sexed semen to breed heifers to produce more replacement heifer candidates as a logical application of this technology. Advantages would include less calving difficulty (no big bull calves) and a hastened introduction of the freshest genetics to the breeding herd. This would also allow most mature cows to be bred for a terminal cross, since replacements would be chosen from calves born to first-calf heifers.
Cloning. Another “new” technology, cloning isn’t all that different than planting potatoes. It’s a form of asexual reproduction, where a piece of the original organism is used to produce a genetically identical organism. One way is to divide an embryo into two pieces to produce twins, but clones can be produced from body cells taken from skin, roots of hair, or somatic cells from milk or semen.
Seidel says practical value might be derived from cloning an animal that is genetically outstanding, but the success rate is low. Cloned embryos are transferred to recipient cows for gestation, but abortion rates are high, and a relatively high percentage of those that survive after birth are abnormal. And cloning is extremely expensive.
Transgenics. With the ability to sequence the bovine genome also has come the ability to add, delete, and modify its parts, Seidel said. In other words, it is possible to change an animal’s DNA. Termed transgenics, Seidel said this technology may represent the ultimate tool for animal breeding. After “correcting” an animal’s DNA, the change would be passed on and present in all of the animal’s offspring.
“An example would be to take an outstanding horned Hereford bull, obtain some skin cells, modify the DNA sequence from horned to polled, in a homozygous way, clone from the modified cells, and end up with an exact copy of the bull – except for being polled. And all of his offspring would be polled,” Seidel explained.
The procedure has become quite reliable, but costs are too high to make it practical for the beef industry. Additionally, the concept of transgenics prompts food safety concerns among some segments of society.
Seidel says most of the technologies discussed will be limited to niche applications in the near term. Eventually, they may become sufficiently inexpensive and efficacious to be as widely practiced as estrus synchronization and artificial insemination are today.
— by Troy Smith
Editor’s Note: This article is available as a news release to redistribute per an agreement between the symposium hosts and Angus Productions Inc. Click here to submit a request for a high-resolution photo of the speaker. For additional information visit the newsroom of www.appliedreprostrategies.com.
The Robert E. Taylor Memorial Symposium is conducted by Colorado State University every other year to provide current, research-based information for improving profitability in the beef cattle industry. The ARSBC program was developed by the Beef Cattle Reproduction Task Force to improve understanding and application of reproductive technologies, including AI, estrus synchronization and factors affecting male fertility. In 2008, CSU and the Task Force collaborated to provide the Dec. 2-3 symposium in Fort Collins. To listen to this presentation, view the accompanying PowerPoint or view other presentations from the symposium, visit the newsroom at www.appliedreprostrategies.com.