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Feeding behavior can be measured using automated calf milk feeding systems, that record total number of visits consisting of rewarded (milk consumed) or unrewarded (no milk consumed) visits. Unrewarded visits can be either when the calf is entitled to milk, but does not drink (“Entitled”), or is not entitled to milk, so cannot drink (“Non-entitled”). Feeding behavior can be used as an indicator of sickness in calves; fewer unrewarded visits to an automated feeder has been shown to be a sensitive measure of the onset of illness. However, a greater understanding of sickness behavior would aid in early detection of disease in calves. This study aimed to evaluate unrewarded visits prior to signs of clinical illness in calves. Calves were group-housed in pens with an automated feeder from approximately 1 wk of age and examined daily for signs of illness. Of the 74 calves, 16 were diagnosed with neonatal calf diarrhea. To examine the feeding behavior during the 5 days leading up to calves displaying clinical signs of illness, we calculated a robust estimate of the daily rate of change (the Kendall-Theil slope) over this time and used the one sample t-test to test whether the slopes were significantly different from zero. During the 5 days before clinical signs of illness, there was a decrease in unrewarded visits, in accordance with other studies. Interestingly, the proportion of “Non-entitled” unrewarded visits decreased (KT slope = -0.05, P = 0.037) whereas “Entitled” increased (KT slope = 0.04, P = 0.038). These results suggest that during the days leading up to clinical signs of neonatal calf diarrhea, calves may be less motivated to drink even though they are entitled to, possibly due to reduced appetite |
