NEW YORK — The Orthodox Union's advanced seminars on kashrut are so popular that more than 170 people have been turned away since the program's inception last year.

Dubbed "Ask O.U.," the seminar was designed to provide a "course not offered anywhere else," said Rabbi Yosef Grossman, director of the program, which is sponsored by the world's largest kosher food certification agency.

The goal, Grossman said, is to provide hands-on demonstrations of the latest developments in the ever-changing field of kosher food technology.

Nearly 60 men attended this year's weeklong conference in New York, which is open to congregational rabbis, rabbinical students and those involved in the kashrut field all over the world.

"People who come have a theoretical knowledge but may not have a practical knowledge." And those who have a practical knowledge don't have all the resources of the O.U., Grossman said.

At the recent conference students learned, among other things, how to establish a community kashrut agency, provide supervision to food factories and set up hotels for kosher catering.

Students also took field trips to a kosher restaurant, food factory and meat processing plant.

One rabbi compared the seminar to continuing education.

"If you don't go to school, you lose something," said Yitzchak Gallor, a Seattle rabbi who works for a local kosher food supervision agency.

The seminar allows the participants to put into practice the theory they learned in yeshiva, said Rabbi Betzalel Marinovsky, a participant from Houston.

Marinovsky said that with the knowledge he has acquired here, he will be able to serve his community better.

Among those who attended this summer's conference was Rabbi Yitzhak Asiel, the assistant rabbi of Yugoslavia, now comprising Serbia and Montenegro.

Asiel is based in Belgrade, but travels to smaller Jewish communities, including those in Serbian-controlled areas of Bosnia several times a year. He also goes to Slovakia twice a year to slaughter animals and cut meat according to Jewish law.

It is "very hard to be kosher in Yugoslavia," Asiel said, because there is "no organized kosher industry."

Asiel cited other reasons why it is hard to keep kosher in Yugoslavia. Since the country is still under partial international sanctions, people are poor, lacking the funds "to spend more on kosher food."

Asiel, who realized "how important kosher is" while studying in Israel, took several steps to help his community.

With the help of the American Jewish Joint Distribution Committee, he bought a freezer and plates, enabling him to hold communal meals in Belgrade three times a year — on Rosh Hashanah, Purim and Passover. Some 250 people attend those meals.

By attending the seminar, Asiel said he has learned "what exists now" in terms of kosher food and technology.

Indeed, it was the appeal of learning the latest in food technology and strengthening ties with the O.U. that attracted many of the participants.

"I feel you can't be a quality mashgiach [kosher food supervisor] unless you have access to the cutting edge of kashrut," said Seattle's Gallor.

With more and more companies interested in appealing to the kosher consumer, there is a growing need for the resources of a national organization, he added.

Nechemia Rozenhaus, an immigrant from the former Soviet Union who serves as an acting rabbi in Richmond, Va., said, "My knowledge is insufficient in this field and when I saw the ad I wanted to participate."

Rozenhaus said he kept kosher for many years even while he lived in the former Soviet republic of Uzbekistan. Today he encourages other Russian immigrants in Richmond to do the same.