Association between neutrophil functions and periparturient disorders in cows

Area of Science:

• Veterinary Immunology
• Dairy Cattle Health
• Infectious Disease

Background:

• Periparturient dairy cows experience significant physiological changes impacting immune function.
• Neutrophil dysfunction is implicated in postpartum diseases like retained placenta, metritis, and mastitis.
• Understanding neutrophil function is crucial for improving herd health and productivity.

Purpose of the Study:

• To evaluate neutrophil function in healthy and diseased periparturient dairy cows.
• To identify potential predisposing factors for postpartum infections.
• To investigate the in vitro effects of specific compounds on neutrophil function.

Main Methods:

• Blood samples collected weekly from 1.5 weeks prepartum to 4 weeks postpartum from healthy and diseased cows (n=97).
• Neutrophil function assessed using six assays: random migration, chemotaxis, ingestion, myeloperoxidase activity, superoxide production, and antibody-dependent cell-mediated cytotoxicity.
• In vitro incubation of neutrophils with arachidonic acid metabolites and recombinant human colony-stimulating factors (rhCSF).

Main Results:

• Neutrophil function varied seasonally and showed defects in cows with retained placenta, metritis, or mastitis.
• Prepartum neutrophil superoxide production and chemotaxis were lower in cows later diagnosed with metritis and mastitis, respectively.
• In vitro treatments with arachidonic acid metabolites or rhCSF did not improve neutrophil function; however, simple preincubation altered function.

Conclusions:

• Host defense via neutrophils is impaired in periparturient cows, especially in killing capacity, increasing infection risk.
• Neutrophil function defects may predispose cows to postpartum diseases.
• Current in vitro interventions with arachidonic acid metabolites and rhCSF are ineffective in restoring neutrophil function in affected cows.