DENVER » Just a few miles from the midday bustle of this city’s hip downtown, a pen of black-hided yearlings trotted into a dusty arena as a crowd of burly men in cowboy hats looked on silently.

"I’m in the market for some heifers," whispered one cattle rancher, eyeing the animals up and down. "If the price is right, I’ll be buying."

For more than a century now, the National Western Stock Show has been a proud totem of the old frontier – a place where rodeos, ranching and cowboys still live and breathe, even as Denver’s cow town roots have long since faded.

These days, as lofts and breweries spring up in the once blighted industrial neighborhoods near the old stockyards, the show has also become a colorful illustration of just how strikingly life on the range has changed. And there is perhaps no greater example of this shift than cattle ranching.

As suburbs around the West have crept farther out onto the plains and the cost of raising cattle has risen, the number of cattle has dwindled to the lowest level since 1952, according to 2013 data from the U.S. Department of Agriculture. Years of drought have also left pastureland harder to come by, ranchers say.

At the stock show last week, generations of ranchers who come each January to showcase and sell their animals told of the marked changes they have had to make in recent years to maintain their livelihoods and traditions. Gone are the days when a cattleman could simply eyeball his herd to figure out which animals to breed; these days, cutting-edge genetic techniques are used to identify the strongest cattle and those requiring the least amount of grass.

"It’s a tough, rapidly changing business," said Marshall Ernst, a cattle rancher from Windsor, Colo., who serves as senior director of livestock operations at the two-week stock show, which runs through Sunday. "Those who are not taking advantage of new technology or are resistant to change may not be able to survive."

Finding good, knowledgeable cowboys has also become harder as more people have moved to cities away from the rural communities that raised them, cattlemen here said. And these days, ranchers must spend considerably more money and time on marketing their cattle over the Internet to stay relevant and profitable.

At a showcase of breeding cattle last week, ranchers drawled quietly into their cellphones, negotiating sales and checking on business back home. From his front-row seat, Newley Hutchison, a sixth-generation rancher from Seiling, Okla., whose ancestors were original homesteaders, watched intently as a set of prized heifers he was trying to sell stared blankly out at the crowd. He talked of the mounting pressure ranchers feel to keep up with all the advancements, like the newest genetic markers being used for herds and the latest computerized equipment to maximize the efficiency of land.

Still, Hutchison said, some aspects of ranch work will never change.

"A cow still eats grass, and she always will," Hutchison, 40, said with a chuckle. "You still have to have devout faith in the creator because there are a lot of variables you have no control over."

By day’s end, 22 of his family ranch’s heifers, including the ones being displayed, had fetched $1,700 a head.

To be sure, beef cattle prices have risen sharply of late, driven in part by historically low inventories. But the increasing costs of feeding and caring for cattle have prompted more ranchers to get out of the business, said Mike Miller, a senior vice president for the National Cattlemen’s Beef Association, which has its headquarters in Centennial, Colo., not far from the stockyards.

Fifty years ago, Miller said, a family of four could make a decent living off 250 cows. These days, it would take more than twice as many for the same family to earn the same amount of money, he said.

"Generationally, things change," Miller said. "We’ve got kids that grow up on farms and ranches. They watch their mom and dad work extremely hard, and in some cases not make very much money. And they decide that’s not the life for them."

Kyle Schnell, one of the few men in the crowd without a cowboy hat, watched the competition with his wife and two children. Schnell, 35, grew up on his family’s cattle ranch in western Nebraska. But at 17, he decided he wanted to do something different.

"Honestly, it was too much work," he said with a grin. "I’m in the technology field. It’s a little easier than waking up at 4 in the morning and staying out until it’s dark."

Every year, though, Schnell and his family travel to the stock show from their home in Windsor, Colo., to support Schnell’s younger brother and father, who still run the ranch and show their cattle here.

"My brother has always had it in his blood," Schnell said. "He got a couple of agricultural degrees in college and came right back. It’s still something I want to keep around my kids, for sure."

The stock show continues to be a huge regional draw. More than 600,000 people attend each year, a number that has held largely steady for two decades.

Outside the arena, little boys in cowboy hats darted in and out of a warren of cattle pens, while an elegantly dressed couple wearing blazers and riding pants gazed admiringly at a sleeping calf.

Courtney Jacobs, a kindergarten teacher from Denver, pointed out the cows to her young daughter. Jacobs, 33, has been coming to the stock show since she was 3.

"I’m a city girl, but my parents wanted me to be immersed in ranching and farming because we were never around it growing up," she said. "Ranching, farming, they are the arteries of our society, and I want my daughter to know that, too."

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Dan Frosch, New York Times

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