It is late afternoon on the first day of the Iowa Pork Congress and the time has come for Porkett Seminar No. 2. The woman at the microphone -- the one who calls herself the Queen of the Pigs -- is dimpled, perky and exuding the wholesome ebullience known in the Midwest as pep. Her subject is motherly love among hogs. Her audience of 82 farmers's wives is rapt.

"If any of you gals are thinking about geting out there in the barnyard, you should know there are some occupational hazards," the dimpled woman says, and peppily goes on to list them: stillborn pigs, fighting boars, sows that sit down on their litters, frozen hog-water pipes, manure-encrusted hog houses, and other hog-business horrors.

The woman at the microphone is Soo Greiman. She changed her name from Sue to Soo (as in sooeeee) when she was back in high school, growing up on her father's hog farm and hungering for the title of National Pork Queen. She won the title in 1973, and now, at the age of 28, with a son named Dusty and daughter named Katie Soo, she's happily raising hogs with her husband near Waterloo, Iowa. She's always loved hogs and believes they like her, too.

That's why she came to Des Moines this week to join nearly 10,000 Iowa hog farmers for the annual gathering of the Hawkeye State's porcine believers -- the men and women who make their livings off hogs and who think the animals are sorely underrated. Presidential politics has put Iowa in the headlines, but pigs pay the bills.

The coquettish Miss Piggy of Muppets fame has achieved the cover of People magazine as a sex symbol. Pig cookie jars, pig underwear, neckties and innumerable bric-a-brac have become such high fashion that New West magazine dubbed 1979 "The Year of the Pig." Hogs are chic, but so misunderstood. Ergo, Iowa. Nowhere in the United States -- indeed, nowhere in the world -- is there a better place for exploring the mysteries of the much maligned beast of glory.

There are eight hogs for every man, woman and child in Iowa. Of the 67.6 million hogs in the United States, 16 million of them -- nearly one-quarter of the national hog horde -- live in Iowa.Hogs here have paid off more mortgages than any other livestrock animal or crop. Hog manure in Iowa is a major pollution problem. Television commercials here have featured the romantic snout-touching of a boar and a sow on a hilltop as an orchestra played the theme from "Love Story."

Hogs have become part of this state's consciousness, giving the hogs a status unknown in the East, where the foul similes of pigness persist (ugly as . . . smelly as . . . lazy as . . . ). There is an unmistakable niceness, a straightforward friendliness, an ineffable peppiness among hog people here.

As hog authority William Hedgepeth ha written in "The Hog Book," "Iowa is the nation's richest state [in terms of hogs]. There seems to be a direct correlation between this and the fact that one so rarely, if ever, reads reports coming out of Iowa having to do with muggings, rapes, riots, rampaging hippies, gangland shootouts or other anti-social behavior. Nay, Iowa is veritably suffused with overwhelming wholesomeness."

The thousands of hog people who invaded Des Moines for three days this week brought with them fond memories of hogs that have been special in their lives. The excitement of crowning a new Iowa pork queen, of strolling through display after display of the newest in hog technology or of attending parties sponsored by hog implement companies could not shake many hog people from tales of porcine wonder. There were stories of leaping hogs for whom a fence was not an obstacle but an athletic challenge, of cute little piglets that grew up in the house and of sows whose fecundity was legendary.

Lloyd Martin, a hog man from Marion, Iowa, who this week was named the master seed stock producer of Iowa, told of his close relationship with Golden Oscar, a 500-pound Hampshire boar.

"The hog is not a dumb animal. We had this old boar that was my favorite. Its name was Golden Oscar. When I'd go out to its pen, I'd tap a stick on the fence and he'd come a-runnin'. He knew what was gonna happen. Then I'd get on him and ride him over to the sows. I'd let him in with them and when he got through with his job I'd ride him back to his pen."

Hogs not only touch the heart of many hog men here; they are fodder, too, for good clean jokes. Jerry Burchele, a Grafton hog farmer, asked two of his peers this week if they'd heard the one about the hog man who was advised one day to take his prize hog to the state fair instead of the slaughterhouse. The next day, that hog man was seen in his pickup truck with the prize hog sitting right beside him. Asked what for, the hog man said: "I had such a good time at the fair, I thought I'd take him to a ball game."

Given the hog's national reputation for grunting, gluttony and generally boorish behavior, the reader outside Iowa may wonder what the attraction is. How can these unique swine-human relationships develop in Iowa?

There are clues in popular culture and children's literature. Aside from the ever-popular Miss Piggy, Arnold Ziffle of the television show "Green Acres" was a pig of great stature and Porky the Pig continues to draw well among children uninitiated in hog prejudice. But the hog men of Iowa say the best way to understand the hog and his appeal is to look carefully at the hogs themselves. What are the facts? Mao's Golden Rule

One, hogs and humans are the most populous large mammals on earth. There are a quarter-billion hogs in China, and a national longing for more. As Mao Tse tung's Golden Rule of pig production is popularly translated, "One man, one pig."

Two, hogs are smarter than horses, chicken, goats, cows, dogs and cats. Studies show only some primates (monkeys) are brighter. A hog can easily learn a dog's tricks -- pointing, birding, flushing, retrieving. The hog is limited only by bad eyesight.

Three, hogs will never eat enough to make themselves sick. They know when to back away from the feeder -- unlike horses or cows, who will eat themselves to death.

Four, hogs are more fecund than any domestic animal save that moral pigmy, the rabbit. A sow usually produces more than 16 piglets a year. Despite their breeding prowess, boars are naturally monogamous, catting around the hog house only because of the two-a-day breeding demands of agribusiness. Six Minutes of Bliss

Five, hogs are reported to have the longest orgasm of any farm animal. Six full minutes of hog heaven.

Six, hogs are the cleanest of all barnyard animals. Hogs will not dung where they sleep, unlike those indiscriminate beasts, the horse, the cow and the sheep. Hogs, which cannot sweat, roll in mud holes only to keep cool. Given the option of clean water, they will bathe in it.

Seven, hogs are not nearly as fat as they used to be . In the last 20 years selective breeding has reduced the fat on a 220-pound hog from 30 to 14 percent of its total weight.

Eight, hogs are remarkably similar to humans in their anatomy and physiology. Hog heart valves are transplanted routinely into humans. Hog teeth are the same size as human teeth.

Nine, hogs are more efficient meat machines than cows or sheep, converting nearly 35 percent of their food into pork. (The chicken, it must be admitted is the most efficient, converting 50 percent of its food into chicken.)

And last, despite their seemingly unlimited potential, most hogs die young. They do not go willingly. They are sacrificed at the altar of commerce, with nearly 60 percent killed by the age of 6 months. Although students of cliches disagree, there is at least one school of thought that looks at the hog as the progenitor of the saying, "Only the good die young."

There have been instances where hogs, presumably striking out in anger at a world that kills them so mercilessly, have sought revenge, eating the hog men who feed them. The story is told of a young reporter who went out to cover one such tragedy and came back with the breezy lead sentence: "Edward Rogers went out to feed the pigs today, and feed the pigs he did."

These cases, however, are rare, and never so much as mentioned at a pork congress. The Pork Depression

The hog people in Des Moines this week know these hog facts and, given the slightest opportunity, they'll recite them to the uninitiated. But when the hog people get together among themselves for a little party, they talk about one hog fact that is not happy. Hogs aren't worth what they were last year. In fact, the market-weight hog sells this year for $37, nearly $20 less than he brought last spring.

"My hogs would be a whole lot more interesting if they were worth a little more money," said Marvin Ries, who sells 2,000 hogs a year from his 320-acre farm in Delaware County, Iowa.

Ries was bemoaning hog losses while sipping free liquor at the K&L Swine Service party on the fourth floor of the Des Moines Ramada Inn. K&L has a reputation, among hog people who like free drinks, for parties that don't end for want of booze.

"Our policy is not to run out [of liquor]," said Wilbur Kehrli, the "K" of K&L, a company that tests and sells items such as hog houses, hog pens and a new product called "Tenderfoot" -- plastic-coated wire mesh for little pigs to walk on without hurting their feet.

"And actually," Kehrli continued, "because our parties are good, clean fun, [hog] producers bring their wives. We haven't had a fight yet." Uncle Moe & Jolting Johnny

Besides the whooping, hollering, broad-shouldered good times that are to be expected when hog people get together over liquor, there was considerable shoptalk at the K&L hospitality suite this week. For example, Gordon MacDonald, who sells confinement gestation stalls (pens where pregnant sows are kept before the blessed day), was telling Kehrli about his wares.

"We have what I feel is the most efficient gestation stall around, Wilbur.

That yard of yours is gonna have one before I'm through with you," MacDonald said.

Wilbur Kehrli smiled.

The hog man smiling in the face of a man who wants to seel him something is probably the most common scene here at the Iowa Pork Congress, where 216 hog-implement, hog-fed and hog-breeding companies set up displays to catch the farmer's eye.

"There's everything here that a hog needs and a lot of things he don't need," said Lloyd Martin, the hog man who used to ride Golden Oscar to the sows.

There was, among other hog items, "Uncle Moe's Pig Holder Number Two." It holds a pig by its back legs while a hog man checks for lice, castrates it or administers medicine. Uncle Moe, according to the free brochures, offers "absolutely the closest thing to another human being in the way it holds the little pigs."

Also on sale was the Jolting Johnn y Blitz Board," a device used by the hog man who wants to get in a hog pen and move his animal around without a lot of pushing. The Blitz Board has hot wires on one side that jolt a hog in the desired direction. The Coronation

The Iowa Pork Producers Assn., which runs the Pork Congress, knows that even a hog man needs more than hardware to keep him excited at a convention. Therefore, a banquet was held which ended with the moment the hog farmers were told they'd all been waiting for: the crowning of the Iowa Pork Queen for 1980.

The pork queen, according to one insider, has to grow up on a farm and be proud that her parents are pork producers. According to this source, a woman who asks not to be identified, "You don't want an ugly gal as the pork queen because that projects the wrong image."

The 16 candidates here for pork queen were attractive young women in their late teens, who were not at all ashamed of being associated with hogs. Janine Stewart of Waverly proudly listed her hobbies as "sewing, reading, showing hogs and being with friends." She didn't win, though.

With tears running down her cheeks, it was Marla Joy Smith, 19, of Oskaloosa, who won the title. For her spontaneous answers to a question about the need for government involvement in the pork industry, Marla said: "It is our industry working with the government that is going to keep the pork industry on top."

Marla will go out for one year across the country to grocery stores and food fairs to promote pork. She will say that hogs are clean and smart and meaty. For that honor, Marla received a crown, a banner, a pigskin coat, roses and a $200 check.

As Marla posed teary-eyed for photographers after receiving her crown Wednesday night, the piano player at the pork banquet played "Pomp and Circumstance" and the master of ceremonies spoke these solemn words:

"Let's go out and be proud of Iowa and move that pork."