By Leah Douglas and Tom Polansek
(Reuters) – Dairy cows infected with bird flu in five U.S. states have died or been slaughtered by farmers because they did not recover, state officials and academics told Reuters.
Reports of the deaths suggest that the bird flu outbreak in cows could take a greater economic toll on the agricultural sector than initially thought. Farmers have long been clearing out poultry infected with the virus, but raising cows costs much more than raising chickens or turkeys.
A spokesperson for the U.S. Department of Agriculture said the agency was aware of some deaths, but that the vast majority of cows are recovering well. Reuters could not determine the total number of cows with bird flu that died or were killed in South Dakota, Michigan, Texas, Ohio and Colorado.
Avian flu has infected dairy cows in more than 80 herds in 10 states since late March, according to the USDA.
Some animals died from secondary infections they contracted after bird flu weakened their immune systems, said state veterinarians, agriculture officials and academics who helped lead the state’s bird flu response. Other cows were killed by farmers because they did not recover from the virus.
Cattle infected with bird flu suffer from reduced milk production, digestive problems, fever and loss of appetite, according to farmers and veterinarians.
In South Dakota, a dairy farm with 1,700 cows sent a dozen animals to slaughter after they failed to recover from the virus, and killed another dozen that suffered secondary infections, said Russ Daly, a professor at South Dakota State University and veterinarian for the state information agency that spoke to the farm.
“You get sick cows from one disease, and that creates a domino effect for other things, like routine pneumonia and digestive problems,” Daly said.
A Michigan farm killed about 10% of 200 infected cows after they too failed to recover from the virus, said Phil Durst, an educator with Michigan State University Extension who spoke to that farm.
Michigan has more confirmed infections in livestock than any state, as well as two out of three confirmed cases of U.S. dairy workers contracting bird flu.
In Colorado, some dairies reported culling cows with bird flu because they did not return to milk production, said Olga Robak, spokesperson for the state Department of Agriculture.
Ohio Department of Agriculture spokesperson Meghan Harshbarger said infected cows have died in Ohio and other affected states, mainly due to secondary infections.
The Texas Animal Health Commission also confirmed that cows have died from secondary infections at some dairy farms with bird flu outbreaks.
Officials could not provide numbers on the number of cow deaths statewide.
New Mexico’s state veterinarian, Samantha Uhrig, said farmers increasingly culled cows because of reduced milk production early in the outbreak, before the U.S. even confirmed that bird flu was infecting livestock. The culling slowed down when farmers discovered that most cows were gradually recovering, she said.
Officials in North Carolina and Kansas said there have been few to no cow deaths in their states due to bird flu. Idaho officials did not respond to requests for information.
Bird flu virus particles were found in beef tissue taken from a dairy cow sent to slaughter for meat, and meat from the animal did not enter the food supply, the USDA said last month.
The agency has reported that no virus particles were found in samples of ground beef collected at stores, and that no bird flu virus was found after cooking ground beef to medium to well done after it was injected with a virus surrogate as part of a study. experiment.
