Validation of an automated cell counter to determine leukocyte differential counts in neonatal Holstein calves

Abstract

Morbidity and mortality in calf rearing facilities is known to be high early in the production cycle causing large amounts of antimicrobials to be used for group metaphylaxis after arrival. With recent work focusing on identifying risk factors and biomarkers associated with mortality risk in calves arriving at veal facilities, it may be possible to reduce antimicrobial use after arrival by selectively treating only high risk calves. For a selective antimicrobial therapy protocol to be implemented without a decline in animal health and welfare, further refinement of calf risk assessment is required to increase the sensitivity and specificity of risk status determination. Rapid, on-farm white blood cell differential counts presents an opportunity to improve disease risk assessment in young calves when interpreted with clinical exam findings. The objective of this prospective cross-sectional diagnostic accuracy study was to validate an automated leukocyte cell counter, the QScout BLD test (Advanced Animal Diagnostic, Morrisville, NC), in its ability to determine leukocyte differential cell counts in neonatal Holstein calves.