MEXICO CITY, JUNE 2 -- What's two feet tall, gives a gallon of milk a day and moos?

The answer: a full-grown Mexican mini-cow, the diminutive result of 17 years of experimentation in animal husbandry by creative cattlemen and researchers at Mexico's national university.

Bred in the sweltering ranchlands of northeastern Mexico, 30 of these abbreviated Brahman-type cattle are now happily grazing alongside their bulkier brethren, unaware that they are pioneers in what their designers see as a potential agricultural revolution.

"Our idea was to create a low-cost animal, one that could be easily maintained in a small amount of space and without much resources," said Juan Manuel Berruecos Villalobos, the director of the Veterinary Medicine School at the National Autonomous University of Mexico.

Beginning with one of the largest kinds of cattle anywhere -- an Indo-Brazilian zebu, which stands nearly six feet tall and weighs up to 2,000 pounds -- Berruecos has bred selectively over five generations a dwarf version of the same animal that averages just 300 pounds in weight and two to three feet in height.

Horses and other farm animals have been similarly reduced in scale by breeders elsewhere, Berruecos noted in an interview, but what surprised the Mexican researchers "was the unexpected productivity of the small cow as a milk producer. They were producing three to four liters daily, compared to the six liters or so you get from a full-sized zebu cow."

The advantage of what he has dubbed the mini-cow, Berruecos said, is that up to 10 can survive on three acres of grassland, or about what it takes to support one normal zebu. Berruecos is now planning parallel experiments with milk-producing Jerseys and other breeds and enthusiastically envisions entire miniature farmyards stocked with downsized fowl and pigs.

These Morris Minors of the bovine world began as a hobby for Angel Castrillon Nales, an anthropologist and third-generation rancher in Tamuin, in the verdant lowlands 50 miles inland from Tampico.

Berruecos, a veterinarian with a doctorate in genetics from North Carolina State University, became his scientific adviser and collaborator. Castrillon's Tanleon ranch is now home to 18 adult miniature cows and a dozen minute calves.

The latest calves "are really very, very small -- shorter than our turkeys, in fact," said Anabella Castrillon, Angel's wife, today in a telephone interview.

"The little cows are cute, but they are almost too tame," said Anabella Castrillon, who grew up on a cattle ranch. "When you try to move them, they just stand there and look at you."

One complication of the cows' small stature, Berruecos acknowledged, is that they tend to disappear in the local elephant grass. "Sometimes we lose a few for a while," he said.

Recent publicity, which Berruecos said he inadvertently started by discussing the mini-cow project on a national radio talk show, is transforming the animals into Mexican media stars. Reporters and camera crews were dispatched from the capital and, later, from South America and Europe.

An American amusement park offered to buy the entire little herd. Notimex, the Mexican government's news agency, weighed in with a lengthy editorial effusively praising the project and suggesting that while it "might seem laughable," the day could come when urban families prefer tiny Holsteins to cats or dogs.

"A cow won't greet us wagging its tail, of course, but it could be a notable help to the family economy," Notimex said, proposing that the animals be kept on rooftops and nourished with leftovers from the dinner table.

Berruecos and other agricultural experts, though, view miniature cattle primarily as a protein source for the typical rural family. In Mexico, as in much of the rest of the Third World, few poor farmers have enough high-quality grazing land to support even a single cow, and store-bought milk and meat is beyond the family budget.

In the project's next phase, Berruecos plans to experiment with embryonic implants, gestating as many as eight mini-cow fetuses in a single normal-sized adult cow. Through this and other methods, he expects to speed reproduction to the point where there could be more than 100 miniature animals by this time next year.

"What Berruecos is doing could turn into the animal equivalent of the Green Revolution" -- the boom in wheat production that followed development of a new strain here in Mexico -- said Samuel del Villar, a former adviser to the president.

Del Villar now divides his time between lecturing at graduate schools and raising goats on a ranch near Tamuin. He and other staunch defenders of the economic "efficiency" of goat protein concede, albeit reluctantly, that most Mexican consumers prefer cow products.

The Castrillons, meanwhile, natives of a region where cattle are still rounded up by cowboys on horseback, have begun thinking about getting terriers for their corralling chores. "The truth is, though, that you don't even need a dog for these little things," said Anabella Castrillon. "You could do just as well walking behind them beating a drum."