Article 1 (1) of Regulation (EEC) No 3901/89 defines lambs fattened as heavy carcases as those which have been the subject, after weaning, of a declaration of stock sent for fattening in verifiable batches and have reached a minimum average weight of 25 kilograms following a minimum period of fattening of 45 days ... In cases where lambs are fattened in a Member State other than that in which the producer lodged his premium application and fattening declaration a procedure for administrative cooperation between the competent authorities of the two Member States must be set up and such procedures are to be notified to the Commission.