SAO PAULO—Brazil, the world’s largest beef exporter, has suspended beef exports to its No. 1 customer China after confirming two cases of atypical mad cow disease in two separate domestic meat plants, the agriculture ministry said on Saturday. The suspension, which is part of an animal health pact agreed between China and Brazil and is designed to allow Beijing time to take stock of the problem, begins immediately, the ministry said in a statement. China will decide when to begin importing again, it added. The suspension is a major blow for Brazilian farmers: China and Hong Kong buy more than half of Brazil’s beef exports. The cases were identified in meat plants in the states of Mato Grosso and Minas Gerais, the ministry said. It said they were the fourth and fifth cases of atypical mad cow disease that have been detected in Brazil in 23 years. It said atypical …