Hoping to juice up its sales, the dairy industry is making big changes in the looks of the plastic jug, created half a century ago.

New on the market are a pitcher-like jug so easy to pour from that a 4-year-old can use it -- without spilling -- and jazzy single-serving bottles of flavored milk aimed at teen-age boys that would replace the half-pint cartons that are the staple of school cafeterias.

"The milk industry realized some years ago that it had to perk up its act a bit, or appear more relevant to consumers, especially young consumers," said John Sicher, editor of Beverage Digest.

For years, milk has been steadily losing market share to soft drinks, juice, bottled water and other beverages. Milk consumption dropped from 19.4 gallons per person in 1988 to 18.2 gallons in 1998.

Enter the Milk Chug, single-serve bottles of flavored milk introduced by the nation's second biggest dairy processor, Dean Foods Co. of Franklin Park, Ill. Sales totaled $100 million in 1999 and are projected to double to $200 million this year as the product is introduced nationwide, thanks to a new technology that the company says triples the shelf life of milk to six weeks or more.

Now mostly in convenience stores and supermarkets, Milk Chugs will soon be sold in vending machines in Philadelphia. A smaller competitor, Smith Dairy of Orrville, Ohio, has a similar product called Moover selling in convenience stores in New Jersey and several Midwest states.

The drinks give kids a healthy alternative to soda, said Eric Blanchard, a Dean Foods spokesman.

"That's the main goal, to get people to drink a healthier product that is still fun and tastes good," Blanchard said. "For years, you didn't have the convenience or the portability or the re-sealability with the standard half-pint or a pint of milk."

The new three-liter milk jugs are aimed at younger kids -- and their parents. First introduced in Canton, Ohio, last year, the new jug was designed so a child could pour a glass by tilting the bottle rather than lifting it up. So far, the "rock and pour" jug can only be found in limited markets, primarily in Ohio, Michigan and New York, but it soon will be available in Virginia and North Carolina as well.

"I love it, it's really a neat design," said Eric Tim, who manages a Churchill supermarket in Toledo, Ohio, that recently started selling the new bottles. "My 12-year-old doesn't spill it all over the counter any more."

Dallas-based Suiza Foods, the nation's biggest dairy processor, is test marketing an oval-shaped jug of its own in New England, Nevada and Michigan.

"It's been sort of a long time coming," said Art Jaeger, assistant director of the Consumer Federation of America. "I think it's a positive step."

Jaeger's one concern is that retailers will price the three-liter bottles -- which contain about 101.5 ounces -- the same as gallon jugs with 128 ounces.

Even when the three-liter bottles sell for less, the gallon jugs remain a slightly better buy.

In the Churchill stores, the three-liter bottles are selling for $2.19 each -- 2.16 cents per ounce -- while the gallon jugs next to them cost $2.59, or 2.02 cents per ounce. Wegmans, a chain based in Rochester, N.Y., is selling the 3-liter bottles for $2.00 -- 1.97 cents per ounce -- compared with $2.42 for the gallon jugs -- 1.89 cents per ounce.

No one expects the familiar jugs and cartons to disappear any time soon.

Still, "the industry has recognized that it has to invest in ways to make the packaging more consumer friendly," said Susan Ruland, a spokeswoman for the International Dairy Foods Association. "If you don't do that, you're losing out to the Cokes, and Pepsis and Frutopias of the world."

On the Net: International Dairy Foods Association: http://www.idfa.org