It is known that providing high quality colostrum is important for ensuring a calf receives a solid foundation for building the immune system. How we usually check colostrum quality, as well as failure of passive transfer of immunity in calves, is by measuring IgG or protein of the serum or plasma concentration (either directly or indirectly). And while IgG (antibodies) are an important component of the immune system, they are only one part of the immune system, which means there may be other aspects of colostrum that are important for calf immunity that are being ignored. For example, researchers have identified immune cells in colostrum and have looked into their ability to help the calf fight disease as well.
Recently, a study performed at Virginia Tech looked at immune cells in colostrum and their effects on immune cell profiles in calf blood and potential benefits on calf health. The study treatments consisted of feeding calves either whole colostrum (WC) or cell-free colostrum (CFC), which represented colostrum that was unaltered (i.e. containing immune cells), or colostrum that did not contain viable immune cells, respectively (Figure 1). The CFC treatment was prepared by rapidly freezing the colostrum in a plastic bag with liquid nitrogen to lyse the cells and then warming it back up (~98.6°F) before feeding. It was hypothesized that WC calves would have enhanced levels of immune cells in the blood compared to CFC calves. All calves were separated from their dams at birth to prevent suckling and were subsequently fed 2 quarts of colostrum within 3 hours of birth and then fed another 2 quarts between 5 to 8 hours after birth. Blood samples were taken before the first colostrum feeding and then at various time points after feeding colostrum. Antibody concentrations were determined and specific immune cells were isolated from the blood samples and quantified. The immune cells measured are able to show the difference in how the WC or CFC treatments would alter the calf’s immune system to be able to respond to disease. Also, fecal and respiratory scores were taken daily for each calf using the Calf Health Scoring Chart from the University of Madison-Wisconsin School of Veterinary Medicine to detect any symptoms of potential illness.
In summary, it was found that there was no difference in IgG concentrations (or any immunoglobulins) between treatments, increases in particular immune cells of interest (specific T lymphocytes) as well as decreases in other immune cells of interest (a specific T lymphocyte and monocytes) between treatments, and no differences in fecal scores, but an increase in CFC calves indicating respiratory illness compared to WC calves. Immunology can be a confusing field to understand, but altogether it was concluded that immune cells transferred to the calf via colostrum may aid in enhancing an immune response to a disease as seen by the differences in immune cells and the case of respiratory illness in CFC compared to WC calves.
Findings from this research support the idea that there may be more than just IgG levels in colostrum that are important to consider. Practically, feeding whole colostrum from her dam may pose some problems, but it may end up being beneficial for calf health as well. The verdict is still out on how important colostral immune cells can be for developing a calf’s immune system, but signs are positive. It should be noted there is nothing wrong with using IgG to assess colostrum or serum in calves, but that there may be more to the story that we need to keep investigating to make sure our calves are getting the best colostrum to support their budding immune systems.
Virginia Cooperative Extension materials are available for public use, reprint, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.
May 2, 2016