Investigators found no irregularities in the feed records at the California dairy where a 10-year-old cow last month was confirmed to have had bovine spongiform encephalopathy (BSE, or mad cow disease), the U.S. Department of Agriculture stated in a follow-up report this week.

The May 15 report to the World Organization for Animal Health (OIE) also said units of all the feed suppliers to the dairy showed they were in compliance with regulations.

The report, by the USDA’s John Clifford, DVM, reiterated that in this BSE case, the fourth confirmed in the U.S. and the first since 2006, the cow was culled because it was lame, never presented for slaughter for human consumption, did not enter the food suppy and “at no time presented any risk to human health.”

The BSE cow was born at the dairy. Investigators identified two of the cow’s calves and said one born in the last 2 years was stillborn, while another, still living, was humanely euthanized, and tested and found to be negative for BSE.  

The case has been described as atypical BSE, which may be caused by a mutation rather than by eating contaminated feed, the usual cause of the disease.