Mastitis and bovine respiratory disease are examples of diseases caused by many different pathogens, and continued research is needed in these areas. “A multi-etiology disease often suggests an underlying impairment of innate immunity contributing to its development,” Kehrli says. “The importance and need for basic research in these areas is abundantly clear to livestock producers and veterinarians who help produce the most affordable, safe and sustainable food supply in the world.”
Immunity and the transition cow
Proper immune function, like all systems of the body is dependent on proper nutrition – and nowhere is this more evident than in the transition dairy cow that is faced with numerous challenges. Much of the research on innate immunity in bovine medicine is focusing on the role of the innate immune response in defense of the mammary gland.
Nutritional deficiency and chronic stress can certainly impair innate immune responses. Amelia Woolums, DVM, PhD, Dipl. ACVIM, Dipl. ACVM, says hypocalcemia during the transition period in dairy cows, for example, has been shown to be associated with depressed neutrophil function (Kehrli and Goff, J Dairy Sci 1989;72:1188-1196).
Epidemiological data going back decades has identified greater disease incidence in transition cows that experience ketosis and/or milk fever (e.g., higher incidence of mastitis and metritis), adds Marcus Kehrli, Jr., DVM, PhD. “Given the immune system requires a wide array of nutrients to make cells, enzymes, cytokines, antibacterial peptides, antibodies and other soluble glycoproteins of the innate immune system, it only makes common sense that if we short-change the transition cow nutritionally, it will only further enhance her susceptibility to a myriad of infectious diseases – particularly in the first few weeks of lactation.
“Therefore it is absolutely critical that we manage transition cow diets to minimize the effects of both clinical and subclinical hypocalcemia and ketosis. In addition, we know the importance of a proper balance of vitamin E and selenium to support optimal neutrophil function and defense against mastitis.”