Elevated serum amyloid A concentrations in the first days after calving are an early disease indicator in dairy cows

Abstract Text: Early disease detection is critical for maintaining cow health and productivity.  Serum amyloid A (SAA) is an acute phase protein that is primarily produced in the liver and is elevated in response to infections and tissue damage in dairy cows.  To evaluate whether serum concentrations of SAA may assist in early disease detection, blood samples were taken from 57 Holstein cows at days -21, -14, -7, -3, -1, 0, 1, 3, 7, 14, 21, and 28 relative to calving and analyzed for SAA concentrations.  Cows were grouped based on severity of diseases (no disease, subclinical, mild clinical, and moderate clinical), class of diseases (no disease, metabolic, infectious, both types), time of diagnosis (no disease, 0-3 d, 4-7 d, 8-28 d after calving), and birth complications (yes, no) in early lactation and examined for group differences.  Serum amyloid A concentrations in the first days after calving were higher and elevated  longer in cows that developed diseases in early lactation. Observed group differences reflected the severity of disease and preceded clinical disease diagnosis irrespective of disease class.  Group differences were strongest one day after calving, when 0% (healthy), 43% (subclinical disease), 57% (mild clinical disease), and 72% (moderate clinical disease) of cows had SAA above 125 mg/L (sensitivity for any disease: 66%; specificity: 100%).  Cows with birth complications had higher SAA concentrations 2 wk before calving than cows without birth complications.  Our results support our hypothesis that greater tissue damage and disproportionate inflammatory responses after calving are gateway disorders that increase disease risk in early lactation.  Serum amyloid A can detect those risk factors one day after calving and thereby opens opportunities for prevention and early treatment.

Keywords: biomarker, dairy cows, diseases, serum amyloid A