Behavioural responses to cow-calf separation: The effect of nutritional dependence

Abstract There is increasing interest in keeping dairy cows with their calves during the milk feeding period, and in reducing distress associated with separation. The aim of this study was to investigate how nutritional dependence upon the cow’s milk affects behavioural responses to separation by both the cow and calf. For the first six weeks of life, dependent (n = 10) and semi-dependent (n = 10) calves could suckle from their mother at night, but semi-dependent calves also had ad libitum access to an automated milk feeder (AMF). Independent (n = 10) calves had ad libitum access to an AMF, and their dams wore udder nets to prevent nursing. Once cow and calf were separated, (first a 4 d period of partial separation with fence-line contact followed by total separation when the dam was removed), all calves had ad libitum access to the AMF. We used live, focal-animal observations and classified vocalizations either as high pitched (open mouth) or low pitched (closed mouth). We found that during partial and total separation , independent calves produced fewer high-pitched vocalizations/d than did dependent and semi-dependent calves combined (median: 0.00 vs. 7.2; U = 12.0, z = −3.21, P = 0.001 and 0.00 vs. 0.00; U = 40.5, z = −2.25, P = 0.024 for the two phases respectively) and also tended to produce fewer low-pitched vocalizations during partial separation (0.00 vs. 1.17; U = 29.5, z = −1.90, P = 0.057). Similarly, independent cows tended to produce fewer high-pitched calls during partial separation (0.00 vs. 1.08; U = 31.5, −1.74, P = 0.083) as compared to semi-dependent and dependent cows combined. During the separation phases, 23 calves (four, nine and ten calves) of dependent, semi-dependent and independent treatments, respectively, consumed at least 1.5 L/d from the AMF; these calves spent more time playing (s) ( total separation ; 3.67 vs. 0.00; U = 28, z = −1.99, P = 0.047) and less time close to the separation barrier ( partial separation ; 51.31-81.01-124.44 vs. 134.03-147.23-280.10), produced fewer high-pitched vocalizations during partial separation (0.00 vs. 8.33; U = 16, z = −2.22, P = 0.027), and tended to produce fewer low-pitched vocalizations (0.00 vs. 0.83; U = 21.5, z = −1.73, P = 0.083), than did calves consuming less milk from the AMF. The number of high-pitched vocalizations produced was negatively correlated with the calf’s milk intake ( partial separation; Spearman’s r = −0.770, P