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.