Just a decade ago, pasteurizing colostrum was virtually unheard of in the U.S. dairy industry. Then, as the benefits of pasteurizing waste milk for calves were realized and the practice was embraced on-farm, interest in colostrum was sparked as well. Could the bacteria-reducing, calf-performance-enhancing results of pasteurization also be applied to colostrum?
University of Minnesota veterinary researcher Sandra Godden is a pioneer in the field of heat-treating colostrum. Early efforts to test the practice were not entirely successful, mostly because of the differing characteristics between waste milk and colostrum. “We made many batches of ‘pudding’ and gummed up a lot of equipment in those first attempts,” shares Godden. In addition to creating a product that was an unacceptable consistency for feeding, Godden and other researchers found that the pasteurization process denatured all-important colostral antibodies, lowering immunoglobulin (IgG) levels by up to 30 percent.
Eventually, the Minnesota team arrived on a practice that worked: heating colostrum in batches at a lower temperature (60°C or 140°F), for a longer period of time (60 minutes). Godden is quick to point out that it is important to describe this process as “heat-treating” versus “pasteurizing,” because the time and temperature guidelines do not meet the specifications of true pasteurization.
They proved, though, that the process does significantly lower bacterial levels, including E. coli, Salmonella, Mycoplasma, Listeria and hard-to-kill Mycobacterium paratuberculosis, the bacteria that causes Johne’s disease. And follow-up on calves fed the heat-treated colostrum showed that they had higher 24-hour serum total protein (TP) and IgG levels. “We think this is because there are fewer bacteria in the gut to interfere with passive absorption of antibodies in the colostrum,” says Godden.
Still, studies in a laboratory setting, conducted by trained researchers, are not always guaranteed to translate into real-life application at the farm level. Godden and her teammates were anxious to explore whether this one could.
They worked with six commercial dairy farms in Minnesota and Wisconsin to compare the effects of feeding raw versus heat-treated colostrum to more than 1,000 newborn calves. Farm staff were trained by the researchers but then left to implement the study protocols on their own.
Sarah Kreft, calf manager at Jon-De Farms, Inc., a 1,700-cow dairy near Baldwin, Wis., was one of the cooperating on-farm researchers for the study. “At the time, we still were feeding milk replacer and not even pasteurized waste milk, but I was very curious about switching over,” says Kreft.
“I thought trying the heat-treating process on colostrums would be an interesting test of both the value of the practice and our ability to manage it.”