Early Milk Total and Differential Cell Counts as a Diagnostic Tool to Improve Antimicrobial Therapy Protocols

Abstract

Mastitis is a major cause of antimicrobial treatments either during lactation or at drying off. From a One Health perspective, there should be a balance between the risk of IMI that may impair cow health and welfare and the reduction of antimicrobial usage to decrease antimicrobial resistance, as may happen when applying selective dry-cow therapy. This reduction may be achieved by an early and accurate diagnosis followed by prudent and rationale therapeutical protocols. This study aims to assess the accuracy of PLCC (neutrophils + lymphocyte count/mL) in identifying cows at risk of having IMI due to major pathogens (S.aureus, Str.agalactiae, Str.uberis, and Str.dysgalactiae), and to simulate the impact of this early diagnosis on the potential number of treatments using a decision-tree model. The results of this study showed that PLCC had an overall accuracy of 77.6%. The results of the decision-tree model based on data from the 12 participating herds, with an overall prevalence of major pathogens of 1.5%, showed a potential decrease in the number of treatments of about 30% (from 3.4% to 2.5%) when PLCC in early lactation (days 5–16) was used to identify cows at risk for major pathogens compared with using SCC at the first milk test (days 17–43). The study confirmed that it is possible to improve animal health and reduce the risk of antimicrobial use through early IMI detection based on PLCC and applying a rationale and prudent antimicrobial protocol.

A First Investigation into the Use of Differential Somatic Cell Count as a Predictor of Udder Health in Sheep

“…Selection for genetic resistance to mastitis can be direct through the diagnosis of the infection (e.g., bacteriological examination of milk and observation of clinical cases of mastitis), or indirect. The microbiological analysis of milk samples to identify the presence of intramammary infections is not applicable as a routine monthly examination in conjunction with the dairy herd improvement milk test due to its cost and demanding lab protocol [7]. A robust indirect proxy for selecting against mastitis is somatic cell count (SCC) in milk, a wellknown indicator of udder health and milk quality in dairy animals.…”