Table 27.

Assessment of ABMs for mastitis in terms of feasibility, sensitivity and specificity

ABM	Description of the ABM
Clinical cases	Definition: Incidence rate of clinical mastitis. Increased clinical cases is indicative of more severe welfare impairment. Feasibility: High – although dependent on availability and accuracy of vet/farm records Sensitivity and Specificity: High sensitivity and high specificity rely on complete and accurate recording of clinical mastitis events on‐farm
Bulk milk somatic cell count	Definition: Bulk milk somatic cell count (SCC). Increased SCC indicates more severe welfare impairment. Feasibility: High – records readily available Sensitivity and Specificity: Low sensitivity (because not all cows with acute mastitis will contribute to milk in the bulk tank (milk withdrawn) and in addition, individual cases may not be detectable because of dilution) and low specificity due to e.g. high average age of herd
Individual cow somatic cell count (SCC)	Definition: Specified increases in individual cow SCC values between consecutive monthly recordings (or in case of AMS between milkings) to indicate a new infection has occurred. Feasibility: High – but information not routinely available in all farms (even fewer farms with AMS) Sensitivity and Specificity: Low sensitivity because acute cases of mastitis that occur between sampling time points may be missed. Possibly reduced specificity because other factors may increase SCC (e.g. end of lactation).
Bacterial culture; screening of individual cow milk samples	Definition: Screening of individual cow milk samples for pathogens indicative of mastitis. Feasibility: Low – it requires exact sampling and lab analysis Sensitivity and Specificity: Low sensitivity because most clinical cases might be missed at a one‐time herd screening. Low specificity for clinical mastitis because some pathogens do not lead to clinical signs.