Studies on the survival of Salmonella dublin, S. typhimurium and E. coli in stored bovine colostrum
Wray, C.; Callow, R.J.
Veterinary Record 94(18): 407-412
1974
ISSN/ISBN: 0042-4900 PMID: 4605178 Document Number: 81093
Salmonellae did not survive for >10 days in colostrum stored for 4 and 7 days prior to inoculation and subsequently kept at 16-21 deg C. In similar colostrum samples, stored at 5-11 deg C, inocula of 106 salmonellae/ml survived for periods ranging from 16 to 32 days, whilst inocula of 104/ml were not isolated after 20 days of storage. [At 4 deg C, salmonellae survived for 28-38 days and Escherichia coli for >36 days.] In fresh colostrum (collected on the 4th day after parturition) stored at 16-21 deg C, salmonellae survived for >37 days in one batch and for <10 days in another. E. coli survived for periods of >36 days irrespective of the environmental temp. In citrate phosphate, buffer and buffered nutrient broth, salmonellae and E. coli respectively were killed at pH 3.4 and 3, but in acidified colostrum, the organisms did not survive at pH <4.5. These findings suggest that the natural bactericidal activity of colostrum is probably of greater importance in killing added pathogenic bacteria than are low pH values resulting from souring, and that the temp. of storage is also an important factor. Results are discussed with regard to the possible risk of salmonellae and E. coli infection that may occur from feeding stored bovine colostrum to calves.