Pasteurized Milk for Calves
Eleanor Jenson, D.V.M.
USU Extension Veterinarian
Raising healthy calves economically with optimal weight gains and minimal sickness is a worthwhile goal for every dairy. One way to achieve this goal is through proper nutrition. This can be attained by feeding whole milk, rather than milk replacer. Besides being more economical, whole milk contains more energy and protein compared to milk replacer. Whole milk supplies about 2331 kcal of metabolizable energy per gallon fed, whereas milk replacer supplies only 1980 kcal per gallon fed, or about 85% of the energy in a gallon of whole milk. Besides facilitating growth, this added energy helps to maintain body temperature and aid response to vaccines and the presence of pathogens. When calves are not receiving enough energy (via milk), they are more susceptible to illness and mortality increases. Conversely, when calves are provided more energy, they perform better.
Despite its economic and nutritional advantage, waste milk may contain an abundance of bacteria and other pathogens. These pathogens may include Salmonella, Mycoplasma, and Mycobacterium avium subspecies paratuberculosis, the causative agent of Johne�s disease. These pathogens can cause illness in calves, resulting in poor growth rates and the added expense of treating sick calves. In the case of Johne�s disease, the pathogen may remain dormant in the calf�s intestinal tract for several years, only to cause severe diarrhea later in life.
One strategy to decrease pathogen load and still utilize waste milk is to pasteurize the milk. Pasteurization does not sterilize milk; however, it does limit the number and type of pathogens passed from adult cows to calves via waste milk. Two types of pasteurization exist. Batch pasteurizers slowly heat milk to a low temperature (145 F) for a long time (30 minutes or greater). This method is suitable for small-scale pasteurization. Continuous flow or high-temperature, short-term (HTST) pasteurizers rapidly heat milk to a high temperature (161 F) for a short time (15 sec). The milk is then immediately cooled.
Colostrum may also be pasteurized, but only the batch pasteurizer is currently suitable for colostrum. The HTST type produces a gelatinous �glob� which may plug the equipment hoses. High quality colostrum should be used, as some of the antibodies are destroyed during pasteurization. One study determined that 25% of antibodies were destroyed during batch pasteurization of 15 gallons of colostrum, and there was a 50% loss of antibodies during batch pasteurization of 30 gallons of colostrum. However, if high quality colostrum is selected for pasteurization, the potential benefits outweigh the loss of antibodies.
Other studies have determined that feeding calves pasteurized waste milk has advantages in addition to the reduced pathogen load. Calves fed pasteurized milk gained weight faster, had a decreased treatment rate, and decreased mortality rate when compared with calves fed nonpasteurized waste milk. The pasteurization process requires extra time, effort, and management. However, it offers a good potential for an improved calf program to those producers prepared to implement it on their farms.