Abstract
The assessment of the rectal temperature plays an important role in the early detection of bovine respiratory disease (BRD) in young calves, but the measurement is invasive and labor-intensive. The aims of this retrospective field-trial evaluation were to assess the correlation between the automatic measurements of the reticulo-ruminal (ReRu) temperature and the rectal temperature and to evaluate the diagnostic accuracy of a cumulative sum (CUSUM) control chart to detect pre-weaned calves suffering from BRD. In 150 male fattening calves (16.6±3.3 d at arrival) the ReRu-temperature was obtained every 5min automatically with a wireless device over a period of 8 weeks. Data was averaged over periods of 30min and 4–6h (day periods). The 30-min means were further evaluated using CUSUM control charts. All calves were inspected by trained persons at least twice a day and rectal temperatures were measured in calves showing visible signs related to BRD. A ReRu hyperthermia (ReRu temperature ≥40°C) was detected in 139 calves over 30min and in 99 calves over day periods, respectively. During the evaluation period 30 animals were affected by BRD (rectal temperatures ≥40°C and one additional clinical sign). The correlations between rectal temperatures and both the corresponding 30min as well as the day period ReRu temperatures was r=0.75. The sensitivity (Se) and specificity (Sp) of ReRu hyperthermia for the 30min means to detect BRD were 77% and 97%, respectively, whereas means of the day periods had a Se of 61% and a Sp of 97%. The CUSUM test revealed a Se of 71% and Sp of 98% to detect BRD. On average, by the CUSUM method calves with clinical signs of BRD were identified 3.5 d earlier. In conclusion, the automated ReRu temperature measurement possesses potential for the early detection of febrile responses in very young calves warranting further investigations.
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