Improved Sex-Sorting of Livestock Sperm
May 4, 1999
Sperm-sorting technology that could allow
livestock producers to predetermine the sex of their animals has been
significantly improved by the Agricultural
Research Service scientists who developed the original technology. ARS is
the U.S. Department of Agricultures
chief scientific research agency.
Animal physiologist Lawrence A. Johnson, head of ARS
Germplasm and Gamete
Physiology Laboratory in Beltsville, Md., developed the patented Beltsville
Sperm Sexing Technology a decade ago. The method separates living
female-producing X-chromosome sperm from male-producing Y-chromosome sperm
based on their content of genetic material called DNA.
In the past year, Johnson and colleagues have improved the rate of sexed
sperm production by 15 to 20 fold, enhancing sexed sperms adaptability
for livestock reproduction worldwide.
The technology uses a fluorescent dye that sticks to sperm based on how much
DNA the sperm contain. The X-chromosome sperm contain about 4 percent more DNA
and therefore hold more dye. This extra dye means they give off more light than
Y-chromosome sperm as the sperm pass through the laser beam of a high-speed
sperm sorter in Johnsons laboratory. The sperm are collected in separate
tubes with 90 to 100 percent accuracy and with much higher efficiency than in
the original technology.
Johnson is collaborating with several scientists around the world to
establish and perfect the technology for commercial development in livestock.
To date, more than 500 animals have been born using sexed semen. All of the
animals were healthy and normal. The sperm sorting technology has also been
licensed for biomedical use in humans.
An in-depth article appears in the May issue of Agricultural Research magazine.
The story is also on the World Wide Web at:
Scientific contact: Lawrence A.
Johnson, ARS Germplasm and Gamete Physiology Laboratory, Beltsville, Md.;
phone (301) 504-8545, fax (301) 504-5123,