Brazil suspended beef exports to China after a case of mad cow disease was reported in Mato Grosso state, dealing another blow to the nation’s meat exporters.

Shipments have been temporarily suspended in compliance with quarantine and sanitary protocols between Brazil and China, according to the South American nation’s agriculture ministry. Meat cargoes shipped after May 30 must be returned to producers or redirected to other destinations.

The suspension was a protocol measure and may be reviewed soon as Chinese authorities review the details of the case, a press official for the agriculture ministry said by phone.

Meat producer Minerva SA closed down 2.2% in Sao Paulo while larger rival JBS SA lost 2.4%. The export suspension was first reported by local newspaper Valor Economico.

The ministry said late Friday a 17-year-old cow with bovine spongiform encephalopathy, or BSE, was found in Mato Grosso. The case was considered “atypical” as the animal contracted the neurological disease spontaneously instead of through contaminated meat-and-bone meal.

Atypical BSE also differs from the classical variety linked to Creutzfeldt-Jakob disease in people. The infected cow didn’t enter the food-supply chain, and the sanitary risk status for classical BSE remains “insignificant,” the ministry said.

Brazilian meat producers have faced a string of bad news including export bans since a major food-safety scandal broke two years ago. China is the largest destination for the country’s beef, accounting for about 20% of total shipments.