Immunological parameters of periparturient Holstein cattle: genetic variation.

The genetic variability of blood neutrophil functions, lymphocyte blastogenic responses to mitogens, serum Ig concentrations, and serum complement and conglutinin activities was investigated from 35 d prepartum to 35 d postpartum for 137 Holstein cows. Periparturient cows experience an immunosuppression of various immunologic parameters at calving. Heritability estimates were obtained before, during, and after the episodes of immunosuppression. Significant genetic variability occurred in the periparturient changes for total number of neutrophils, neutrophil chemokinesis, assays of the neutrophil respiratory burst associated with phagocytosis (cytochrome c reduction, chemiluminescence, and iodination), serum concentrations of IgG1, IgG2, and IgM, and serum homolytic complement activity. This variability implies that immune profiles could be used for the selection of cattle with improved innate immune response without adverse effects on milk productivity. These results should be considered tentative, however, because the number of observations included in the data were limited.