In a problem herd the losses by E. coli-infection of weaning piglets could not be reduced neither applicating an oral vaccine before 4-2 weeks to weaning nor via feed of antibiotics or sulfonamides. Therefore many feeding trials were carried out by 1247 weaning piglets which are feeded with high raw fibre rations (wheatbran coarse grained, strawmeal) beginning 2 weeks before weaning till 3 weeks afterwards. The most effective feeding additive was 25-30% wheatbran. In fact of this results the diarrhea, a problem in many herds infected with a lot of EEC (08, 045, 0138, 0139, 0141, 0147 and 0149) could be reduced effectively. Light cases of diarrhea during the trials could be stopped by two applications of TMQ (20 mg Terramycin/kg BW). Based on these results the use of the supplementing wheatbran to the normal feed during the weaning period can be recommended for such problem herds.