This study was conducted on 6 commercial dairy farms in Minnesota and Wisconsin to describe the effect of heat treatment (at 60°C for 60min) on colostrum, on colostrum bacteria counts, and immunoglobulin G concentrations. First-milking colostrum was collected each day, pooled, divided into 2 aliquots, and then 1 aliquot was heat treated in a commercial batch pasteurizer at 60°C for 60min. Frozen samples of pre- and post- heat-treated colostrum were submitted for standard microbial culture (total plate count and total coliform count, cfu/mL) and testing for immunoglobulin G concentrations (mg/mL). Data were analyzed from 266 unique batches of colostrum. Linear regression showed that heat treatment decreased colostrum total plate counts (-2.25 log10) and coliform counts (-2.49 log10), but, overall, did not affect colostrum IgG concentration. Though higher-quality batches of colostrum did experience a greater magnitude of loss of IgG as a result of heat treatment as compared with lower- or intermediate-quality batches of colostrum, the colostral IgG concentrations in these batches remained high overall, and within acceptable limits for feeding. This study demonstrates that batch heat treatment of colostrum at 60°C for 60min can be successfully conducted on commercial dairy farms by farm staff to decrease colostrum microbial counts while maintaining colostrum IgG concentrations.
Bibliographical noteFunding Information:
This study was funded by a grant from the US Department of Agriculture-Cooperative State Research, Education , and Extension Service (USDA-CSREES) . The authors thank the owners and managers of the 6 dairy herds for their participation and support. We also thank Amber Hazel, Eb Ballinger, Jennifer Belz, and Katie Konkol (of the University of Minnesota, St. Paul) for their technical assistance.
- Heat treatment