ELBA, N.Y. — The demands of 3,800 heifers at CY Farms dictate the rhythm of labor. Farm workers deliver feed down a central aisle of a massive barn. They scrape away manure with tractors. They inject the cows with vitamin B. On a rainy day, the din on the huge metal roof drowns out the moos.

But beyond the usual problems with tractor repairs and feed prices, this season has brought a new worry: the serious threat that farm workers will be deported as part of President Trump’s immigration crackdown.

Migrant labor has long been essential to the dairy farmers in the rolling fields of Western New York. Now, those farmers are arriving at work every day wondering how many of their employees will still be there.

Migrant workers, especially those who are undocumented, also worry; they are afraid to leave their employers’ farms to shop because they fear being apprehended by authorities and deported. Reports of workers being picked off farms throughout the country have only added to the atmosphere of fear hanging over the idyllic farming community.

At CY Farms, managing partner Craig Yunker has a longtime Mexican worker who has won annual work permits from the federal government for the last 10 years. But the latest permit has not been renewed yet, despite inquiries to the local office of Immigration and Customs Enforcement.

Yunker and the worker, Sergio — who used a plastic tube to float across the Rio Grande in 1988 to get to the United States — are increasingly anxious Sergio will be targeted for deportation.

Sergio, who asked that his last name not be used, does not want to return to the ICE office and ask about his permit after hearing high-profile stories in the media since Trump’s election of people who have been detained and sent back to their native countries, leaving families behind.

“Our whole life has been here,’’ said Sergio, who rose from picking cabbage in the field to being one of CY Farms’ most trusted workers. His 18-year-old son — who was born in the United States — recently started working at the farm, too.

“This uncertainty is a big problem for us as his employer, too,’’ Yunker said. If Sergio’s work permit is not renewed, Yunker worries he wouldn’t be able to replace him. He said his farm will not hire workers without all the proper documents.

Yunker also scoffed at the notion that Sergio is taking a job from a US citizen. He has ample proof that is just not the case.

“We’ve tried the local labor office where you go and say we have work, and they’ll send somebody out and they’ll try it for an hour, two hours maybe, or they’ll come out and look at the field and look at the job and say, ‘I’m not doing this’ and walk,’’ Yunker said.

The dairy industry is a year-round enterprise, not seasonal like harvesting crops. But there’s no year-round guest-worker program that could provide a steady flow of legal workers from outside the United States. The result: The Pew Research Center says 26 percent of farm workers are undocumented, but experts say that number climbs to nearly 50 to 75 percent of workers on dairy farms.

“We will lose our food security, we will lose a major piece of our rural economies, and we will lose jobs,’’ said Craig Regelbrugge, the national cochairman of the Agriculture Coalition for Immigration Reform, about the importance of foreign workers. He said there are between 1 million and 1½ million unauthorized farm workers in the United States.

In Buffalo, there has already been increased enforcement activity with officials targeting the “low-hanging fruit,’’ said Meghan Maloney de Zaldivar, the senior associate for regional outreach at the New York Immigration Coalition.

She said law enforcement has picked up undocumented individuals whom they’ve had contact with in the past, putting them into deportation proceedings. When those individuals come from farms, it spells trouble for the farmers as well as the migrants’ families.

“I’m assuming if you want milk to drink and ice cream to eat, this issue needs to be addressed because there wouldn’t be any,’’ said Rich Stein, who is the second-generation owner of Stein Family Farms in nearby Caledonia, about the difficulty of finding legal workers.

Sergio lives in a two-bedroom apartment with his wife and three kids in Byron, a five-minute drive from the farm. Years back, the family used to occupy a three-bedroom house, but one day after immigration officers knocked on the door and brought Sergio to the nearby detention center — later putting him under a supervision program — he decided to sell it amidst worries he would be deported.

In their current living situation, the two eldest children, who are 18 and 16 years old, share a room, and his youngest son sleeps in the same room as Sergio and his wife. All three of his children are US citizens and have no connection to their parents’ native country.

“We’re just in jeopardy right now,’’ Sergio said as he helped his 7-year-old son with his math homework. “We don’t want to be afraid of what’s going to happen.’’

If CY Farms lost its Hispanic workforce, revenue would drop by 75 percent, Yunker estimated, because they would have to resort to growing lower-value crops such as corn, soybeans, and wheat. This year, Yunker said they’re debating whether they can grow cabbage, a high-value crop, but one that requires strenuous manual labor.

For Yunker, who has voted for the Republican presidential candidate in every election with the exception of Richard Nixon, Trump’s takeover of the Republican Party was difficult to watch. Yunker was the chief elected official in Genesee County in the late ’80s, and, in 1986, he unsuccessfully ran for the Republican nomination for the congressional seat. But, when he went into the voting booth this year, he left the top line empty.

Between Trump’s derogatory comments about Mexican workers — Yunker said he would trust his firstborn with his own workers — and his rhetoric on trade, Yunker couldn’t bring himself to vote for Trump.

“It is just remarkable that this society could produce a president like that,’’ he said.

A Livingston County farmer, who declined to be identified for fear of angering his workers, said he voted for Trump because of his stance against abortion, a decision he made the Sunday before Election Day after attending church. Although he’s still hopeful Trump will grow into the position, he regrets his vote.

“I was hoping he was going to do a lot of good for the country,’’ he said.

Representative Chris Collins, the first member of Congress to endorse Trump, represents Yunker’s district, which includes large swaths of Western New York farmland. Amid rising anxiety among his constituents, Collins said he has met with many farmers to reassure them of his support for their workers. He wants to see a legal guest-worker program for dairy workers created in the vein of the H2A visa, which allows farmers to hire foreign workers for seasonal agricultural work.

“I want to see them get work papers because we need to milk the cows three times a day and we need workers out in the field,’’ he said. “These are typically jobs that Americans do not want but they are essential jobs.’’

Still, his continued support of Trump has many of his constituents disappointed as they worry about the stability of their workforce. Trump promised mass deportations during his presidential campaign, but ICE said it does not “conduct sweeps or raids that target aliens indiscriminately.’’

“ICE focuses its enforcement resources on individuals who pose a threat to national security, public safety, and border security,’’ ICE spokeswoman Dani Bennett said in a statement. “ICE conducts targeted immigration enforcement in compliance with federal law and agency policy.’’

Collins said Trump wants to prioritize securing the border and deporting “the criminal element’’ and then deal with the undocumented workers who are currently in the United States “with compassion.’’

Progress on the issue, however, is still at least six months away as repealing the Affordable Care Act and tax reform are at the top of the president’s agenda, Collins said.

Despite Collins’s stated opposition to the deportation of law-abiding undocumented workers, more than a dozen farmers declined to speak on the record with the Globe, expressing serious concerns about ICE raids and the potential of losing their workers.

“We don’t want to have a target on our back,’’ said one dairy farmer in Livingston County.

Another farmer added, “They’re going to pick and choose who potentially they go out and just make an example of, so we’re right square in the bull’s-eye of that. That’s our fear.’’

Farmers and experts maintain that these labor issues have persisted for years, but they say the new administration has exacerbated the problem.

“It seems to be the official policy is going to be much more intrusive and stricter than it has been, which is very unfortunate because you’re talking about very important economic activity that is hindered by the fear and even more hindered if there’s actually enforcement activity,’’ said Marc Smith, a retired senior extension associate at Cornell University.

In Orleans County, the Rosario family operates a retailer similar to a Costco, specializing in Hispanic products. Piñatas hang from the ceiling of the store, colorful boots line the wall, and Spanish delicacies can be found in each aisle. The family has owned the store for nearly 11 years, catering primarily to the thousands of Hispanic farm workers in the area.

As deportation fears mount among those workers, most of whom are likely undocumented, the family has seen a spike in their delivery service — a response to migrants’ fear of going to public places such as shopping areas. Although the family has always offered to deliver goods to workers on the farms, the service was rarely used. Now, it’s a necessity, both for migrants and the Rosarios’ business.

“If we didn’t do a delivery service, I would probably have to close my business because I wouldn’t have enough to keep the business,’’ Francisco Rosario, the patriarch of the family who started out as a migrant farm worker, said in Spanish.

The Rosario family requested their business not be named for fear that police are targeting Hispanic businesses, looking for undocumented workers.

One farm worker, who has been deported twice after being caught at the border, said he keeps coming back to the United States because he is married to a US citizen and Mexico is too dangerous. He requested anonymity because he does not have legal documentation.

“Every time I go to the store, I look first for the police. If I see something, I don’t go in there,’’ he said. “I stay out of trouble.’’

Rich Stein, the dairy farmer in Caledonia, takes his workers to Walmart every Thursday afternoon. Often, four or five of them accompany him. Last week, the trip didn’t happen. None of the workers wanted to leave the farm.

Stein’s farm has roughly 750 cows and is staffed by nine Hispanic workers. He said he will not hire any workers without proper documentation.

“I am scared because you hear and see on the news that immigration officers are taking people,’’ Edgar, a 20-year-old worker from Guatemala, said in Spanish as he waited for his dentist appointment at the Geneseo Migrant Center in Leicester. “In my country, there’s no work and there’s no money.’’

The Migrant Center, a nearly 50-year-old establishment that offers medical services and coordinates educational programs, is in touch with more than 1,000 people a year.

Since Trump was elected, Chris Norton, the executive director of the center, said Hispanic farm workers — whether they are legally documented or not — have been trying to keep a low profile. They don’t want to draw any unnecessary attention to themselves, he said.

The crackdowns, they fear, however, aren’t a wholly new concern for the farming community.

Maria Orozco remembers the cold winter night she spent sleeping in a vegetable field when she was 8 years old. Rumors had spread in her Orange County, N.Y., community that immigration officials were going to raid the farms. Her parents didn’t want to take any chances.

Orozco, who crossed the border when she was 5 years old, is now 38 years old and a US citizen working at the Geneseo Migrant Center as the coordinator of the High School Equivalency Program. With Trump’s rhetoric and policies, she’s worried more children may have to sleep in the fields just like she did.

“Those words are coming from fear,’’ she said, as tears streamed down her face. “[Trump] should just meet these families. He should meet my dad. He should meet the millions of people. All they want to do is come here and work. All they want to do is provide for their families.’’

Tyler Pager can be reached at tyler.pager@globe.com. Follow him on Twitter @tylerpager.