An untapped market soon may be available to the United States for importation of livestock embryos from countries with various livestock diseases, a scientist involved with research being conducted by the U.S. Department of Agriculture said.

Testing at the USDA Plum Island Animal Disease Center in New York has shown that embryos taken from cattle and hogs carrying the foot-and-mouth disease virus and riderpest in cattle can be washed by means of a thorough rinsing process to dilute the virus. The process leaves no trace of the virus in young born from livestock implanted with the embryos, said Jerry Callis, a senior science adviser at the center.Speaking at the Livestock Conservation Institute's annual meeting late last week, Mr. Callis said positive results from this research would allow a whole new market for U.S. producers wishing to cross certain domestic animals with exotic breeds.

Cattle in some European countries, as well as South American countries including Brazil, Colombia and Argentina, soon could be tapped for desirable genetic traits, he said. Until now, these cattle have not been available for crossbreeding.

Currently, no importation of embryos is allowed from countries not free of livestock disease, said M.J. Gilsdorf, senior staff veterinarian for the import and export division of the Animal and Plant Health Inspection Service.

However, the division could soon develop regulations on importing embryos

from such countries, depending on the results of the research at Plum Island, he said. A proposal could be in the Federal Register by the end of this year, he said.

Mr. Callis said about 100,000 embryo transfers were done in North America in 1987 among countries free of the livestock disease. If countries with known livestock diseases are allowed to export to the United States, Mr. Callis estimated in the first year several hundred embryo transfers could take place

from each new country.

The United States already imports embryos, mostly from Canada. In 1987, 400 embryos were imported from that country, and through March of 1988, 110 were imported, plus 30 from Costa Rica, Mr. Gilsdorf said.