Assessment of Ventral Tail Base Surface Temperature for the Early Detection of Japanese Black Calves with Fever.

The objective in the present study was to assess the ventral tail base surface temperature (ST) for the early detection of Japanese Black calves with fever. This study collected data from a backgrounding operation in Miyazaki, Japan, that included 153 calves aged 3-4 months. A wearable wireless ST sensor was attached to the surface of the ventral tail base of each calf at its introduction to the farm. The ventral tail base ST was measured every 10 min for one month. The present study conducted an experiment to detect calves with fever using the estimated residual ST (rST), calculated as the estimated rST minus the mean estimated rST for the same time on the previous 3 days, which was obtained using machine learning algorithms. Fever was defined as an increase of ≥1.0 °C for the estimated rST of a calf for 4 consecutive hours. The machine learning algorithm that applied was a random forest, and 15 features were included. The variable importance scores that represented the most important predictors for the detection of calves with fever were the minimum and maximum values during the last 3 h and the difference between the current value and 24- and 48-h minimum. For this prediction model, accuracy, precision, and sensitivity were 98.8%, 72.1%, and 88.1%, respectively. The present study indicated that the early detection of calves with fever can be predicted by monitoring the ventral tail base ST using a wearable wireless sensor.

Economic loss due to treatment of bovine respiratory disease in Japanese Black calves arriving at a backgrounding operation in Miyazaki.

The present study assessed the economic loss due to treatment of bovine respiratory disease (BRD) in Japanese Black calves that were introduced to a backgrounding operation from the age of 3 to 4 months until the age of 10 months. The data collected from a backgrounding operation in Miyazaki, Japan included the records of 2,690 animals entering the farm from 2013 to 2018. The treatment duration was defined as the number of days from the beginning to end of treatment. The cost of treatment was defined as the total cost of treatment during the treatment duration. The average incidence of BRD was 54.6%, and the relative frequency of calves that had BRD once, twice, and three or more times until they left the farm was 64.4%, 26.8%, and 8.8%, respectively (total recorded diagnoses of BRD: 2,494). Among the 2,494 recorded diagnoses, the average and median duration of treatment of BRD was 5.9 days and 3.0 days, respectively. The average and median cost of treatment was 7,767 and 5,600 Japanese yen, respectively. A prolonged duration of treatment and high cost of treatment were associated with BRD relapse, steers, and early stage of production (P<0.05). At the studied farm, the total cost of treatment during the 6-year study period was 19,658,988 yen, and the annual cost was approximately 3 million yen. In summary, the present study showed that BRD had a large economic impact in this backgrounding operation.

Associations between calf factors of Japanese Black calves arriving at a backgrounding operation and bovine respiratory disease.

Bovine respiratory disease (BRD), a common and costly disease of beef cattle, has various causes. In Japan, Japanese Black calves aged 3-4 months were introduced to a backgrounding operation that raises calves until age 10 months. We assessed whether any associations relating to the calf information on arrival at the backgrounding operation and BRD incidence in Japanese Black calves exist. The data collected from a backgrounding operation in Miyazaki (Japan) included the records of 1843 animals entering the farm during 2012-2016. The information collected on arrival at the backgrounding operation was calf sex, age, blood line, weight and chest circumference, and the arrival season. Mixed-effect multivariable logistic regression modeling was applied to these data. The dependent variable was whether or not a calf showed the clinical signs of BRD and was subsequently treated with an antimicrobial between farm entry at 3-4 months of age and farm exit at 10 months of age (1 or 0). The first diagnosis of BRD after arrival was counted in this study. Average BRD incidence was 52.5 %, the relative frequencies of which at 0-30, 31-60 and ≥61 days after arrival were 58.7 %, 25.2 % and 16.1 %, respectively. BRD incidence was associated with sex, age and season (P < 0.05), but not blood line, weight, and chest circumference. Steers had 1.39 times higher odds than heifers of being diagnosed with BRD (P < 0.05). Calves entering in September to November had the highest BRD incidence (65.3 %), whereas those entering during March to May had the lowest BRD incidence (42.3 %; P < 0.05). Calves of ≤125 days old on farm arrival had higher BRD incidence than those ≥148 days old (P < 0.05). Thus, various factors on arrival at the backgrounding operation were found to be associated with BRD incidence in Japanese Black calves. It is important to carefully observe high-risk calves and monitor them for the clinical signs of BRD at the earliest opportunity on arrival at a backgrounding operation.