In this study the frequency of isolation of bacteria from quarter milk samples were compared with the frequency of recovery of bacteria from sediment after centrifugation of the same samples. A total number of 52 quarter milk samples that had normal appearance from 20 cows were obtained prior to milking, taken from four problematic herds. The results of bacteriological culture showed that culture of sediment of quarter milk samples increased the number of positive samples to 154.5% (P<0.01). Centrifugation could enhance sensitivity of standard bacteriological culture methods, especially in the case of milk samples from sub-clinical mastitis in which they were infected and in cattle shedding bacteria at concentrations not detected by the use of standard bacteriologic techniques

Keywords