Relationships between body temperatures and behaviours in lactating dairy cows

Abstract

The welfare of dairy cows is sometimes compromised by anxiety that could be indicated by changes in body temperature. We hypothesized that there was an association between external body surface infrared temperature (IRT) of lactating cows and behavioural responses to anxiety, using rectal temperature as a reference point. Approximately 50 cows were examined individually once a month for 3 consecutive months. Cows were excluded from the evaluation if > 300 d in milk, somatic cell counts exceeded 400 × 1000′s cells/mL, or if dried-off, and so numbers declined over time. Monthly IRT thermograms of each cow’s head and coronary bands of forelimbs were taken, and we collected data deemed indicative of anxiety (behaviour in a forced lateralisation test, behaviour in the crush, flight speed and rectal temperature) as well as potential confounders: temperature humidity index (THI) in the parlour and crush area and lactation variables. The hypothesized positive association between IRT and behavioural indicators of anxiety was found in the first month only, between IRT of both eyes and cows’ sniffing behaviour in the forced lateralisation test. Associations between rectal temperature and behavioural indicators occurred in month 3, when rectal temperature was positively associated with both flight speed and crush score. Cow waiting time prior to being milked was negatively associated with limb IRT in each of the 3 months, and positively associated with the ratio of eyes to limb IRT in 2 of the 3 months, whereas no such associations were detected with rectal temperature. In the analysis across months there were associations between IRT and behavioural indicators, which suggested that limb IRT may relate to cow behaviour: limb IRT was negatively related to slow to medium walking, and the ratio of IRT of eyes to limbs was positively associated with a vertical, rather than horizontal, tail. No associations were detected between laterality and IRT or rectal temperature. The adjusted R2 of the regressions across months was higher for IRT (eyes 86 %; limbs 78 %) than rectal temperature (63 %). IRT had a high repeatability, particularly for both eyes, across the 3 months, whereas rectal temperature was not repeatable. We conclude that there are potential relationships between IRT and cow emotions, but it is important to account for confounders.