RENWICK, IOWA -- Harold Trask's quest for the perfect pig began in 1978. Consumers wanted lean meat and would have nothing else. Pork had to change or face gastronomic oblivion.

"So we bred for lean," said Trask, a rough-cut hog farmer from the central Iowa flatlands. The idea was to achieve "lean pork" -- a linguistic contradiction in terms and a sharp break with tradition in an industry that 40 years ago prided itself on 35-pounds-of-fat-per-animal "lard hogs" that provided shortening for an entire nation.

But it appears to have worked. Last month the University of Wisconsin, working in conjunction with the hog-raising industry and the U.S. Department of Agriculture, published a study showing that retail pork in 1990 was 31 percent lower in fat, and had 17 percent fewer calories and 10 percent less cholesterol than it did in the USDA's 1983 nutrient handbook.

The study is not without its detractors. Jayne Hurley, a nutritionist for the non-profit Center for Science in the Public Interest, said it is "misleading."

"Certain cuts are leaner than they were, but how available are they, and how much fat does the average cut of pork have? The study doesn't tell us." For these reasons, Hurley said, the industry "has not proved" its claim that pork is "the other white meat."

But for Russ Sanders, executive vice president of the National Pork Producers Council, the study is a watershed in a decade-long effort to redeem and renovate the nation's pork supply:

"Pork was the first meat that addressed the fat issue," said Sanders, whose council represents 100,000 hog farmers nationwide. "We're on a product improvement curve that's probably unprecedented in the business."

Modesty is not a virtue of an organization whose goal is to make pork "the meat of choice by the year 2000." They have a way to go, but they are gaining -- somewhat.

USDA forecasts that the United States in 1990 will consume 8 million tons of pork and 12.1 million tons of beef -- the country's biggest-selling meat. In 1986, the numbers were 7.6 million tons for pork and 13.2 million tons for beef.

These gains would be more impressive if chicken hadn't eclipsed them in the same period, with broiler consumption rising from 6.9 million tons in 1986 to an estimated 8.8 million tons this year.

Barry Pfouts, the council's vice president for product marketing, nonetheless remains optimistic that "chicken and fish fatigue" will set in. When it does, he says, pork will take up the slack.

Meanwhile, the council will continue urging restaurants to serve more pork, and urging supermarkets to stock more. The council has even trademarked its own 1 1/2-inch-thick boneless loin chop as "America's cut."

"We're trying to build some long-lost romance for the product," Pfouts said. "I mean, let's face it, raising pigs is not glamorous."

Few would dispute him. If cattle ranching is outlaws, stampedes and blazing sixguns under the big skies of Marlboro Country, hog farming is a bunch of low-roofed sheds filled with ugly, oinking, close-to-the-ground creatures whose chief characteristic lends credence to the phrase: "They stink like pigs."

"They do smell some," admitted Trask. "You want to watch your feet."

Revitalization of the pork industry began with producers like Trask, a 44-year-old Iowa State University graduate who started hog farming in 1972 with 10 sows and 320 acres of rented land.

Today he has 220 sows, each of which produces an average of 2.26 litters per year of eight to 10 piglets each for a total of about 4,200 pigs for market, averaging from 220 to 260 pounds. He sells 50 to 90 pigs per week, depending on the price. Every transaction, as well as the medical and growth history of every animal he owns, is registered with a computer company he has under contract. The firm presents him with a weekly printout.

"I've got a reputation for knowing the markets better than anyone," Trask said. "It's nerve-wracking. I spend about an hour a day seriously looking at the market, maybe two."

The hog farmer as commodity broker is one break with the past. Another is the relative importance farmers accord their pigs. Thirty years ago, swine were an afterthought -- animals that would eat some of the extra feed corn that Iowa and other midwestern states produce in such abundance.

Today raising pigs is so sophisticated that farmers cannot afford to let their charges run loose in the yard all day. Most Iowa pig farmers grow corn, but pigs are what take the time and effort.

"I make about half my income from pork and half from grain," Trask said. "But, yeah, I consider myself a pork producer."

Trask lives on his family's 120-acre farm in Renwick, about 100 miles north of Des Moines, and conducts his business in a clutch of nondescript buildings divided into compartments dedicated to each stage of pig development: breeding, birthing, weaning, growing and "finishing" -- readying pigs for market.

Native intelligence and skill brought Trask some early success, but in 1978 he began to take an interest in leaner pigs. Lard was passe', and pork had begun a slide into obscurity, what the council's Sanders calls "two dried-out pork chops to feed the kids on Wednesday night."

To overhaul the product, Trask and his peers became geneticists, able to juggle breeds, bloodlines and family trees in a continuing search for the perfect animal. Trask's essential message is simple: Breeding leaner pigs is easy; breeding lean pigs that are good reproducers is harder.

"Five, six years ago we had the leanest animals that we ever had," Trask said. "But they couldn't survive because they couldn't move. We had to breed back for a freer-muscled pig."

Lauren Christian, an Iowa State animal scientist who sometimes consults with Trask, believes one answer to breeders' continuing search for a leaner product could be porcine somatotropin or PST, a chemical that artificially duplicates a growth hormone produced by the animals.

PST, Christian said, makes the pig "bigger all over," by prolonging growth and delaying maturity. Test results have shown that PST gives pigs up to a 15 percent increase in daily weight gain, a 25 percent reduction in back fat, and an 18 percent increase in loin muscle mass.

"It's just incredible," Christian said. "One pork chop is half again as big as a regular one with a nicer pink color and less fat. The guys who were testing it were just blown away."

Trask and others in the industry remain skeptical. They are worried that the projected cost of PST -- which is only used experimentally today -- would offset any benefits farmers could achieve in the marketplace.

Trask also worries that consumers will not accept PST-produced pork. Bovine somatotropin, a similar drug designed to make cows give more milk, has caused an uproar among some consumer and small farmer groups. Neither PST nor BST has been found to harm humans.

Still, Trask said, "you have to be aware of what the consumer thinks. I'm here to sell hogs and make money. I don't have these hogs just to look at them."