Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/27/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: We have shown that compositional changes in circulating T-cell populations and reduced functional capacity of circulating neutrophils from periparturient dairy cows are, in part, due to metabolic demands imposed by the presence of the mammary gland. To further characterize effects of the mammary gland on the immune cell function during the periparturient period, we evaluated the capacity pokeweed mitogen (PWM) stimulated peripheral blood mononuclear leukocyte (PBML) from intact and mastectomized Jersey cows to secrete IFN-gamma and polyclonal IgM. Data were summarized and analyzed so that these functions could be examined within 5 d periods beginning at 15-d prepartum and concluding at 14-d postpartum. The capacity of PBML from intact cows to secrete IFN-gamma and IgM changed significantly during the periparturient period. For this group, the nadir of IFN-gamma and IgM secretion occurred at 0-4 d postpartum and -5 to -1 d prepartum. Although PBML from mastectomized cows showed a similar decline in function with approaching parturition and subsequent restoration of function approx. 5-14 d after parturition, effects of parturition on PBML from mastectomized cows were not significant. Differences between IFN-gamma secretion by PBML from intact and mastectomized cows were significant only from birth to 4 d postpartum. Differences between IgM secretion were significant only from -5 to -1 d prepartum. In both cases, PBML from intact cows were less responsive than those from mastectomized cows. These results indicate that parturition causes a pronounced reduction in the functional capacity of bovine PBML and suggest that the metabolic demands placed on the periparturient dairy cow by the mammary gland contribute to the reduction in function.