Short communication: The effect of storage conditions over time on bovine colostral immunoglobulin G concentration, bacteria, and pH

The objective of the present study was to measure the effect of storing colostrum in different conditions for varying amounts of time on IgG concentration, bacteria, and pH. In experiment 1, colostrum from 12 Holstein-Friesian cows (6 primiparous and 6 multiparous) was collected within 3 h of calving, and colostrum from another 12 multiparous cows was collected within 3 h of calving (6 cows) and >9 h postpartum (6 cows). Aliquots were refrigerated or stored at room temperature for up to 72 h, depending on treatment. In experiment 2, colostrum was collected from 6 multiparous cows within 9 h of calving, and aliquots were stored for up to 72 h in temperature-controlled units set at 4, 13, and 20°C. All colostrum samples were analyzed for IgG concentration, total bacteria count, and pH after 0, 6, 12, 24, 36, 48, 60, and 72 h of storage. Storage conditions did not affect the IgG concentration of colostrum. Bacterial growth was most rapid in the first 6 h of storage, reducing thereafter, but bacteria multiplied at a significantly greater rate when stored in warmer conditions (i.e., >4°C). The pH of colostrum was not significantly altered when stored at temperatures <13°C, but when stored at 20°C the pH significantly decreased after 24 h of storage. Storing colostrum in warmer conditions significantly alters both total bacteria count and pH; consequently, colostrum should be stored at ≤4°C.