Improved Sex-Sorting of Livestock Sperm

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 Agriculture’s 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 sperm’s 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 Johnson’s 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:

http://www.ars.usda.gov/is/AR/archive/may99/accu0599.htm

Scientific contact: Lawrence A. Johnson, ARS Germplasm and Gamete Physiology Laboratory, Beltsville, Md.; phone (301) 504-8545, fax (301) 504-5123, lajohnsn@lpsi.barc.usda.gov.