Submitted to: Mastitis Council Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 25, 2009
Publication Date: January 25, 2009
Citation: Kehrli, Jr., M.E., Ridpath, J.F., Neill, J.D. 2009. Immune Suppression in Cattle: Contributors and Consequences. In: Proceedings of the NMC 48th Annual Meeting, January 25-28, 2009, Charlotte, North Carolina. p. 103-112. Technical Abstract: With a $35.7 billion Gross Domestic Value for milk produced in the U.S. during 2007, the dairy industry was the largest commodity group of the 2007 U.S. animal agriculture economic engine (when dairy beef is added). The economic value of controlling mastitis pathogens is immense. Most economic analyses of the cost of mastitis cite a 10% production loss as only one part of the overall cost of the disease. A majority (65 to 70%) of losses are associated with decreased milk yield resulting in lower production efficiencies and the remainder of the costs are attributed to treatment. In addition to these direct losses, mastitis causes significant problems in milk quality control, dairy manufacturing practices, quality and yield of cheese, nutritional quality of milk, antibiotic residue problems in milk, meat and the environment, and genetic losses due to premature culling. Most clinical mastitis occurs in dairy cows in early lactation. Because bovine mastitis is predominantly caused by opportunistic pathogens, scientists hypothesized that periparturient cows must be immune suppressed. Today there is an abundance of scientific evidence supporting the three following concepts: 1) the prepartum mammary gland is highly susceptible to new infections; 2) the postpartum dairy cow is highly susceptible to clinical disease (mastitis, metritis and diarrhea); and 3) the degree and duration of immune suppression is correlated with the increased incidence and severity of clinical mastitis, metritis and retained placental membranes in postpartum cows. Here we review the association between immune suppression and infectious disease, highlight several factors (physiologic, genetic and infectious causes) that contribute to immune suppression in cattle. The consequences of immune suppression are increases in infectious disease and premature loss from the herd both of which add significantly to the cost of production and decrease the profitability of dairy farming. Simple solutions will not likely be found for something as complex as immune suppression, however, without additional significant research into this topic we can be assured that no progress will be made.