Member States shall ensure that, following a bacteriological, pathological or serological examination, animals in which the presence of brucellosis has been officially established and those considered by the competent authorities to be infected are slaughtered under official supervision as soon as possible and not later than 30 days after their owner or the person in charge has been officially notified of the results of the tests and of his obligation, under the eradication plan, to slaughter the cattle concerned within that time limit.