A well-functioning immune system has been shown to support multiple aspects of dairy cattle health and productivity. For example, research suggests that immune health is a major determinant of reproductive function in lactating cows, according to Peter Hansen, Ph.D., of the University of Florida Department of Animal Sciences.

Dr. Hansen notes that a dairy cow’s natural immune function is suppressed by physiological changes that occur during the transition period, including metabolic changes to support lactation. “Cows with poor immune function are more likely to experience disease, and cows that experience disease have poor reproduction,” he said, citing difficulty in the resumption of cyclicity, establishment of pregnancy and fetal survival to term.

Dr. Hansen’s comments came at a pre-conference symposium sponsored by Prince Agri Products Inc. at the recent Tri-State Dairy Nutrition Conference in Ft. Wayne, Indiana. Dr. Hansen presented data from 5,700 postpartum dairy cows on seven dairy farms showing a high incidence of health issues during pregnancy and the first 60 DIM (days in milk), including calving problems, metritis, clinical endometritis, postpartum milk fever, mastitis, clinical ketosis and lameness.

Ken Zanzalari, Ph.D., dairy technology manager for Prince Agri Products, told participants that low blood calcium in postpartum cows in combination with increased blood concentrations of the stress hormone, cortisol, further compromise the immune system. He presented research showing that reduced immune function in hypocalcemic cows is associated with diseases such as retained placenta, mastitis and a higher likelihood of displaced abomasums.

Recommendations from Drs. Hansen and Zanzalari for optimizing transition cow health include:
– Manage transition nutrition to avoid excessive negative energy balance (NEB) and meet or exceed metabolizable protein requirements-
– Select for genes during breeding that improve immune function.
– Exceed National Research Council (NRC) requirements for trace minerals and provide adequate levels of vitamin E.
– Minimize stress associated with high stocking density and excessive pen movements of pre-fresh cows.
– Feed a fully acidified pre-fresh diet beginning at least three weeks before calving to achieve a target urine pH in the range of 5.8 to 6.2.