Table 1.

Schematic overview of the categorization of the five (not mutually exclusive) categories of welfare indicators mentioned in this review as well as their relevance for the three major welfare concerns: health and functioning, affective state, and natural living (14).

Indicator of calf welfare	Health and functioning	Affective state	Natural living
BEHAVIORAL INDICATORS
Feeding	X	X	X
Drinking	X	X	X
Lying	X	X	X
Standing	X
Lying inert	X	X
Locomotion	X		X
Grooming	X	X	X
Self-grooming	X	X	X
Exploring		X	X
Postural changes		X	X
Play behaviorb		X	X
Ruminationb	X	X
Head shakeb		X
Head rubb		X
Ear flickb		X
Head-out-of-penb		X
Tail flickb		X
Foot stampb		X
Fallingb		X
Escape attemptb		X
Rearingb		X
Strugglingb		X
CLINICAL INDICATORS
Respiration	X	X
Heart rate/heart rate variability	X	X
Ocular temperature	X
Nociceptive thresholda	X
Horns or horn buds removed			X
Degree of healing	X	X
Bleeding	X
BLOOD PARAMETERS
Plasma cortisol	X	X
Haptoglobin	X	X
Prostaglandins	X	X
Circulating neutrophils	X
Substance P	X	X
PRODUCTION INDICATORS
Changes in body weight	X		X
Feed intake/milk consumption	X		X
AFFECTIVE STATE INDICATORS
Behavioral indicators marked byb		X
Human verbal report of pain score		X
Pain scale or pain score		X
Cognitive bias		X
Conditioned place avoidance		X

Importantly, strict grouping of the indicators according to welfare concern is complicated and lies beyond the scope of this review. Hence, the distinctions made are not conclusive and reflects decisions made by the authors in order to create overview and stimulate discussion. As indicators of affective state and behavior overlap to a large degree, these are shown together and indicators often interpreted in relation top affective state are marked.

^aChanges in nociceptive threshold are a well-described consequence of tissue damage, inflammation and pain but not a measure of affective state as such.

^bBehavioral indicators often interpreted in relation to affective state.