HORSE SPRINGS, N.M. - Wranglers at the Platt ranch were marking calves the old-fashioned way last week, roping them from horseback and burning a brand onto their haunches.
What they were emphatically not doing, said Jay Platt, the third-generation proprietor of the ranch, was abiding by a federally recommended livestock identification plan, intended to speed the tracing of animal diseases, that has caused an uproar among ranchers. They were not attaching the recommended tags with microchips that would allow the computerized recording of livestock movements from birth to the slaughterhouse.
"This plan is expensive, it's intrusive, and there's no need for it," Mr. Platt said.
Mr. Platt said he already did all he could to fight epidemics. He does not bring any outside animals into his herds, and he happily staples on metal tags that identify animals to help with brucellosis control. But as he drove his pickup from grasslands into dense thickets of piñon pine on this highland desert that requires 100 acres per cow, he explained why he thought the federal plan was wrongheaded.
Mr. Platt called the extra $2 cost of the electronic tags an onerous burden for a teetering industry and said he often moved horses and some of his 1,000 head of cattle among three ranches here and in Arizona. Small groups of cattle are often rounded up in distant spots and herded into a truck by a single person, who could not simultaneously wield the hand-held scanner needed to record individual animal identities, Mr. Platt said. And there is no Internet connection on the ranch for filing to a regional database.
Looking over the 22,000 acres that his cattle share with elk, pronghorns and mountain lions and where animals can easily disappear, Mr. Platt scoffed at the idea of reporting every death, as animal health officials prefer.
"They can't comprehend the vastness of a ranch like this," he said of federal officials. "They don't appreciate what is involved logistically."
Ranchers like Mr. Platt have been joined by small-scale family farmers and other agrarian advocates to oppose the national animal identification system, a plan first broached five years ago by the Bush administration. It has created more visceral opposition than officials expected.
The plan, which is still being ironed out, might have seemed simple enough. With the ever-present threat of animal epidemics, why not modernize the system for identifying livestock? Why not keep computer records of movements so that when a cow is discovered with bovine tuberculosis or mad cow disease, its prior contacts can be swiftly traced? The disease source and the herds needing to be quarantined can be determined faster, officials said.
"Now, when there's an outbreak, we can't trace prior movements quickly, and we end up testing a lot more animals than necessary," said Neil Hammerschmidt, director of the identification program for the federal Agriculture Department. "We want to put in place the infrastructure prior an outbreak."
Mr. Platt expresses his opposition in more measured terms than many. Web sites analyze every official statement with suspicion, and angry farmers have packed the "listening sessions" held around the country this spring by the Obama administration's new agriculture secretary.
Rumors have swirled, and farmers are asking whether the government will really require tags on every baby chick and catfish fingerling or a computer report when a pet pony trots onto a neighbor's land.
Underlying the opposition is the fragile economics of ranches and small farms, which are already disappearing. The extra cost of radio tags, scanners and filing reports when animals change premises would be crushing, some smaller producers say.
"My main beef is that these proposed rules were developed by people sitting in their offices with no real knowledge of animal husbandry and small farms," said Genell Pridgen, an owner of Rainbow Meadow Farms in Snow Hill, N.C., which rotates sheep, cattle, pigs, turkeys and chickens among three properties and sells directly to consumers and co-ops.
"I feel these regulations are draconian," Ms. Pridgen said, "and that lobbyists from corporate mega-agribusiness designed this program to destroy traditional small sustainable agriculture."
Paul Hamby, owner of Hamby Dairy Supply in Maysville, Mo., and a vocal opponent of the plan, said, "It is very much an economic and class warfare issue."
"Fifty years ago," Mr. Hamby said, "hundreds of thousands of farms raised hogs, and now very few players have control of the market. I believe one of the reasons for this plan is to consolidate the cattle industry."
The notion of centralized data banks, even for animals, has also set off alarms among libertarians, drawing former supporters of the Ron Paul presidential campaign like Mr. Hamby into the fray. One group has issued a bumper sticker that reads, "Tracking cattle now, tracking you soon."
Among all the different types of livestock, cattle have the most pressing need for improved records, said Mr. Hammerschmidt, who added that some opponents were misinformed.
"It's never been our intent to implant chickens, especially chicks," he said. "People out there are saying that they have to microchip every chicken, and if that chicken crosses the road they'll have to report that event to the government. That has really stirred the pot."
Nor do officials want every small producer to buy a $1,000 scanner, Mr. Hammerschmidt said. "The tag could be read at the market or feedlot, where they are more likely to have a reader," he said, suggesting looser monitoring than many ranchers fear.
Mr. Hammerschmidt pointed out that Michigan and Wisconsin, to strengthen the fight against bovine tuberculosis, now require radio tags for cattle. But he emphasized that the federal government had not mandated the tags, instead hoping it could prod states and individuals to join in.
"At the end of the day," he said, "we need the ability to trace an animal where there's a disease issue."
Mr. Platt, the rancher, said he believed that the authorities already had ample information to pounce on diseases.
Though he is one of the larger independent ranchers, the business is precarious, Mr. Platt said, sustained by land trades and sales. "Any new expense will mean a loss for us," he said.
Mr. Platt watched with pride as one of his adult sons worked a cutter horse in a timeless ritual, hiving off calves from the herd in the branding corral. "We do this because we just enjoy it," he said.