Throw away that American Gothic stuff about life on the farm. Dispense with the mom-and-pop myths and the craggy-jaw images of the cowboy. Here comes Jo Ann Smith, the newest first lady of American agriculture, a tall and elegant Florida rancher who keeps shattering the cliches.

Since the end of January, Smith has been president of the National Cattlemen's Association (NCA), as big a collection of hard-eyed cusses as you're likely to find, which says more about changes in agriculture than any textbook will tell you.

Smith, who runs a 5,000-acre north-central Florida cattle and crop spread with her husband, Cedric, has launched an aggressive campaign to take the beef story to the public and get the cattlemen more involved in federal agricultural policy making.

That's no easy task, because the NCA, with about 285,000 direct and affiliate members, has not done business that way. The cattlemen nurtured an image as independents unaffected by Washington. They took the view that if you didn't eat beef, you were un-American or daft. Or both.

But the world doesn't work that way, and that fact is dawning only belatedly on the cattlemen. Although meat consumption has held at about 200 pounds per capita for a decade, beef has lost its market predominance to pork and poultry, industries that have shown more skill in giving consumers the leanness and price they want.

And jolts from Washington in the last several years have persuaded cattlemen that they are not immune to federal policy. A new dairy program that sent thousands of cows to market for slaughter gave the cattlemen competitive fits. The 1983 payment-in-kind (PIK) surplus grain giveaway to farmers sent feed prices soaring, to the cattle industry's dismay.

With no lobbying levers to speak of at their control, the NCA grudgingly decided that it was time to join the late 20th century. Enter Jo Ann Smith, who comes on like gangbusters as an advocate for her new-look NCA.

"It is a big shift of our general philosophy, to even address the consumer," she said recently. "We have realized it was not an ideal world we operated in, that we had competition. And we admit that. We didn't advertise that we had a leaner product; we didn't accept that our competition packaged and boxed their product better than we did."

This year, the NCA for the first time will be lobbying on Capitol Hill when Congress gets into the fine print of a new farm bill. The NCA also will be pushing government to reduce deficits and hold down costs to help ranchers and farmers out of their worst financial straits since the Great Depression. This year, Jo Ann Smith will travel the country with the NCA's message.

It is one thing to understand that Jo Ann Smith is the first woman to head a national, traditionally male farmer-rancher organization. It is another, and probably more important, thing to know that with her elevation to the NCA's top job, women's vital role in agriculture is accorded its due.

Although an estimated 4 perent of U.S. farms are run by women and although women from time to time rise to head male-dominated county farm groups, public perceptions of females in farming often seem limited to crownings of the queens of pork or wheat or pomegranates.

The Smith ranch is a joint enterprise, as are many American farming operations, run with her husband and their children. "From the days of the Chisholm Trail until now, women have always played a role on the farm," Smith said. "Women were in the decision-making process. We have made decisions as a team and as a family. I always knew what Cedric was paying for corn."

Jo Ann Smith helps put up hay. She has clambered into the cab of a tractor-trailer and driven loads of cattle to market. She has done the same farm tasks that crack men's shins and strain their backs.

She also has strongly held opinions about how government policies affect agriculture and how farmers and ranchers must educate the public about their problems if they are to remain on the land as producers of food.

Smith's first taste of the NCA's image difficulties occurred in 1977, when she was named to head its beef promotion and consumer relations committee. "A very explosive time," she said, alluding to the critical marks that government and consumer groups were giving beef on health and nutritional grounds.

That job told her how far the NCA had to go to get its message out. Driven by the idea that she could help tell the story, Smith has moved up through the hierarchy, and the top job is hers.

"My responsibility is to communicate the true picture, although there are strong variables in that picture," she said. "The rancher always has been highly leveraged; we operate on borrowed money. Yet we have no control over what we get for our product. There's no way I can pass on to the consumer what that high rate of interest costs me.

"Other industries can pass it on. I cannot. The consumer has no concept of the difference. I just want him to know why we are in the problem we are in, why we have to keep federal spending down to save American agriculture. Not just freeze the budget, but cut it."

Given half a chance, Smith will talk and talk. That goes back to the first grade when she talked so much that the teacher resorted to adhesive tape.

The lesson: Pick your spots. Smith has.