Hundreds of veterinarians, support staff and lab workers at the animal health arm of the U.S. Department of Agriculture have left under the Trump administration's push for resignations, according to three sources familiar with the situation, leaving fewer specialists to respond to animal disease outbreaks. The departures come as the country battles its longest-ever outbreak of bird flu and faces the encroachment of New World screwworm, a flesh-eating pest detected among cattle in Mexico. "With the decrease in USDA veterinary positions, there is concern that fewer veterinarians will be able to perform ongoing regulatory requirements, disease investigations, and response planning and preparation," Kansas animal health commissioner Justin Smith said.