Table 46.

ABMs used for assessment of metabolic disorders: ketosis (KETO), acidosis (SARA), displaced abomasum (LDA) and hypocalcaemia (HYPOCAL), divided into clinical (‘‐c’) and subclinical (‘‐sc’) form

ABM	Description of the ABM
ABMs for clinical ketosis (Keto‐c)
Clinical case incidence rate	Definition: Incidence rate of clinical ketosis (estimated from veterinary diagnoses, farm records or national databases) (Pryce et al., 2016) Feasibility: High ‐ although dependent on accuracy of veterinary/farm records Sensitivity and Specificity: Low sensitivity since some cases may remain unrecorded. Specificity low because an accurate cow‐side diagnosis can be problematic; other conditions such as dilatation or displacement of the abomasum may be present with similar clinical signs (e.g. reduced appetite, changes in behaviour).
ABMs for subclinical ketosis (Keto‐sc)
Individual cow milk constituents	Definition: Individual milk fat:protein ratio or early lactation fat % monitored at routine milk recording Feasibility: High ‐ although it would require all farmers to participate in milk recording. Sensitivity and Specificity: Low sensitivity and medium specificity (factors other than negative energy balance can influence the fat and protein content of milk)
Individual cow beta‐hydroxybutyrate levels or ketones	Definition: Individual cow beta‐hydroxybutyrate levels (blood sample) or ketones (milk or urine samples). Requires regular sampling of a sufficient number of cows (generally ≥ 12) in early lactation to provide effective herd monitoring (Oetzel, 2003). Feasibility: High Sensitivity and Specificity: High sensitivity and high specificity (sensitivity for urine samples likely to be lower than for blood)
Body condition scoring	Definition: Body condition scoring is used to assess the level of body fat by evaluating overall body shape and fat cover with a scoring from 1 to 5 (Welfare Quality, 2009). Feasibility: High ‐ already routinely done Sensitivity and Specificity: Medium sensitivity and medium specificity (body condition score over time provides a useful indicator of energy balance which is related to subclinical ketosis. However, changes in body condition may be related to factors other than ketosis which limits sensitivity and specificity)
ABMs for left displaced Abomasum (LDA)
Clinical case incidence rate	Definition: Incidence rate of left displaced abomasum (estimated from veterinary diagnoses, farm records or national databases) (Pryce et al., 2016) Feasibility: High ‐ although dependent on availability and accuracy of veterinary/farm records Sensitivity and Specificity: High sensitivity and high specificity (accurate veterinary and/or farm records necessary for high sensitivity and specificity to be obtained)
ABMs for sub‐acute ruminal acidosis (SARA)
Individual cow milk constituents	Definition: Individual milk fat%, fat:protein ratio monitored at routine milk recording Feasibility: High ‐ although it would require all farmers to participate in milk recording. Sensitivity and Specificity: Low sensitivity and low specificity (factors other than SARA influence the fat and protein content of milk, therefore sensitivity and specificity limited)
Rumen pH measured by rumenocentesis	Definition: Acidity of the liquid rumen content obtained through puncture of the rumen (Nordlund and Garrett, 1994). A rumen pH measured by rumenocentesis lower than or equal to 5.5 can be considered as a sign of subacute ruminal acidosis (Garrett et al., 1999) Feasibility: Low ‐ too invasive to be used for routine monitoring Sensitivity and Specificity: High sensitivity and specificity
Rumen pH measured by rumen bolus	Definition: Rumen pH can be continually measured by a bolus inserted into the reticulum via a rumen cannula. A bolus pH lower than or equal to 6 is considered as a sign of subacute ruminal acidosis (Neubauer et al., 2018) Feasibility: Low ‐ as technology relatively expensive and requires additional validation but may become realistic with advances in technology Sensitivity and Specificity: High sensitivity and medium specificity
ABMs for clinical hypocalcaemia (Hypocal‐c)
Clinical case incidence rate	Definition: Incidence rate of clinical hypocalcaemia (estimated from veterinary diagnoses, farm records or national databases) (Pryce et al., 2016) Feasibility: High ‐ although dependent on availability and accuracy of vet/farm records Sensitivity and Specificity: High sensitivity and medium specificity (specificity is medium because some cows treated with calcium on‐farm may not be hypocalcaemic)
ABMs for subclinical hypocalcaemia (Hypocal‐sc)
Incidence rate	Definition: Incidence rate (estimated from veterinary diagnoses, farm records or national databases) (Houe et al., 2001) Feasibility: High ‐ although dependent on availability and accuracy of vet/farm records Sensitivity and Specificity: Low sensitivity and low specificity due to very difficult cow‐side diagnosis
Blood calcium levels within days post‐calving	Definition: Blood calcium levels measured by blood sample at 24–48 h after calving. Cows with a serum Ca lower than or equal to 2.14 mM are considered experiencing HYPOCAL‐sc (Rodríguez et al., 2017) Feasibility: Low ‐ requires regular sampling of a sufficient number of cows very close to calving to provide effective herd monitoring Sensitivity and Specificity: High sensitivity and high specificity