The school lunch -- the universal experience for 540,000 Washington-area public school students -- is undergoing major changes in price and content this year as administrators cope with sharp inflation, new federal diet recommendations and an expected $2 million cut in federal lunch subsidies locally.

Prices will rise as much as 20 cents for older students in District of Columbia schools. Portions will shrink for younger children in many area schools. And the weekly diet will include as many as three extra slices of bread or the equivalent in order to meet revised federal nutritional needs.

Additional price increases and other menu changes are predicted for later in the school year as officials adjust to the $500 million national reduction in lunch subsidies, which Congress has approved for the federal fiscal year beginning Oct. 1.

"It will be a disaster," said Joanne Styer, director of the Montgomery County school food services, which serves about 45,000 lunches daily.

Since some differences must be worked out between the Senate and House versions of the subsidy changes, the reductions may not take effect until after the Nov. 4 election. When they do, school districts will receive about 4.5 cents a lunch less than they now get in cash and commodity subsidies from the federal government.

Meantime, area schools are adjusting prices to reflect higher costs and implementing new policies to comply with previously ordered federal rules.

A summary includes:

Higher prices. District of Columbia schools raised prices 15 cents for elementary students and 20 cents for older ones. Fairfax and Alexandria went up 10 cents on all lunches.Falls Church and Prince Gerorge's County increased prices for all lunches by 5 cents. Arlington and Montgomery have the same prices as last year.

"We have had a tremendous increase in food costs and labor costs," said Dorothy VanEgmond-Pannell, director of food services for Fairfax. She said this was the school district's first increase in lunch prices in five years.

More pasta and bread. The U.S. Department of Agriculture now requires to serve eight slices of bread or bread alternate each week in order to meet revised nutritional needs. Last year the minimum requirement was for five bread servings a week.

"We're using pasta -- which is an accepted bread alternate under the department's rules -- and more rice," said Montgomery County food director Styer.

Some other schools, however, said that they have been serving enough bread and bread alternates to meet the new requirements. "This has no impact on us," said C. Antony DiMuzio, director of the Prince George's school food program.

Reduced portions. The Agriculture Department recommended that schools this year serve 1.5 ounces of meat or meat alternate to children in kindergarten through third grade. In the past, the recommendation has been for a two-ounce meat serving.

The department officials said that small children tend to eat less when their servings are too large. In addition, the smaller servings are intended to reduce waste. "This is aimed at better meeting the needs of the younger child," one official said.

Meantime, the department also recommends that larger portions -- three ounces of meat rather than the standard two-ounce size -- he served to older students in grades seven and up.

Among the school districts which have adopted the USDA recommendations is Alexandria. "We have the new school lunch patterns, with smaller portions for the older ones," said Donald V. Miller, the district food director.

Some other districts, however, such as Montgomery, plan to try the portion recommendations on an experimental basis to see if it is effective. And still other schools -- including those in Fairfax -- will have small portions on "a very few items," but don't agree that it is necessary to vary portions for all students.

Students eating school lunches also may notice some other changes in the meals they are served this year. For example, under the new federal recommendations, it now takes two eggs to equal a two-ounce meat serving; last year, one egg was rated as an equivalent.

The amount of cooked dry beans or peas necessary to substitute for a two-ounce meat serving now is one cup. Last year, one-half cup of beans or peas was equivalent.

Although the changes in the diet recommendations and portion sizes are considered the most far-reaching of any since the school lunch program begin in the mid-1940s, school cafeteria generally regard them as reasonable.

"Most of these changes, quite frankly, I find realistic," said DiMuzio, Prince George's food director.

But local cafeteria officials view the proposed subsidy cuts, which passed the House Thursday, with dismay.

"It will mean a 5- to 15-cent a lunch price increase for us," DiMuzio said. Actual price increases in school lunch programs would have to be approved by the school board, however, and would depend on final federal subsidy decisions.

In the Washington area, the District of Columbia probably will be least affected by the subsidy changes. That is because school districts with 60 percent or more children qualifying for free or reduced lunches are exempt from the 4.5-cent-a-lunch subsidy cut.

Of the 53,830 student lunches served each day in District schools, 44,786 -- about 90 percent -- are free or have reduced prices.

The lunch subsidy, as passed by the House, calls for a total reduction of $498 million nationally. That includes $175 million in cash and commodity reductions for lunches: $105 million in cuts by raising the income eligibility for free and reduced-price lunches. The balance of the cuts represent miscellaneous program changes.

One of those changes includes an increase in the price of the reduced-price lunch, from 10 cents now to 20 cents under the new program.