The 200 dead cattle were discovered on a farm field on 4th Street in Amherst. Sunday, the bodies were taken out in semi-loads to be disposed of.
The farm's veterinarian says preliminary results show the animals died of acute interstitial pneumonia, also known as AIP. Samples from the dead animals were sent to Madison for testing.
The vet says the steers began to die early last week, with the last dying Saturday. The animals started showing symptoms of illness and then died within 12 hours. The vet says animals didn't respond to treatment.
The herd's owner declined to comment on the situation.
Investigators say there is no threat to people or other animals. The Portage County Humane Society is investigating the deaths.
The cattle on the farm are not quarantined.