Abnormal protein (called PrP, Prion Protein , PRION is the summary of proteinaceous infectious particle) which is protein degradation process resistant and which is responsible for B.S.E. ( Bovine Spongiform Encephalopaty ) called also "crazy cow disease". This protein could be present in organic fertilizers from animal origin or in amino-acids produced by animal carcasses hydrolysis. PROTAMINAL, produced by enzymatic fermentation of vegetal material is free from this dangerous protein.