Bacteriophage contamination in calf sera collected by different methods from various sources

Abstract

A systematic study was carried out in order to compare the presence and the frequency of different phage types in foetal calf sera collected aseptically in slaughterhouses, in sera collected aseptically from young healthy donor calves and in calf sera obtained under clean but not sterile conditions in slaughterhouses. Twenty-five batches of aseptic calf sera collected from 300 donor calves bred in closed herds were consistently phage-free while 14 out of 16 batches of foetal calf sera showed phage contamination. Calf sera were positive to a lesser extent (8 out of 16 batches). E. coli B and E. coli K 12 proved to the most sensitive strains for detecting phages and their presence can give information about the frequency and the abundance of other enterobacteria phages containing sera. The advantages of using sera collected aseptically from donor calves are discussed.