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We assessed effects of two-step debonding strategies in calf rearing systems with different types of prolonged cow-calf contact (CCC) on stress responses, health and performance of dairy cows and calves. Forty-eight Holstein Friesian cow-calf pairs had either: 1) full contact including suckling, where contact was reduced before weaning via fence-line separation at day 49 (FC-FS) (n = 10); 2) full contact, where contact was reduced at day 56 by fitting calves with a nose-flap (FC-NF) (n = 10); 3) partial contact (calves were housed in a pen adjacent to the cow area allowing physical contact on initiative of the dam but no suckling), where contact was reduced before weaning by moving the calf box from the wall to prevent physical contact at day 49 (PC-BW) (n = 6); 4) partial contact, where contact was reduced the week after weaning by moving the calf box away from the wall at day 63 (PC-AW) (n = 12); 5) no contact (calves were removed from dam directly after birth and housed in a calf barn), calves were weaned at day 56 (NC) (n = 10). Between weeks 7–10, we assessed physiological stress parameters, weight gain, and the health status of calves, plus general activity patterns based on accelerometer sensor data of cow-calf pairs before, during and after the debonding interventions. Additionally, calves were subjected to four consecutive behavioural tests (i.e. open field, novel object, voluntary human approach and involuntary human approach test) prior to permanent separation at day 70 and their behavioural responses were assessed via video recordings to assess fearfulness. Machine-harvested milk yields of cows were evaluated during weeks 6–12. Data were analyzed with (generalized) linear mixed models. Throughout the debonding period, FC-NF calves had an impaired growth rate (P = 0.02). In weeks 6–9, FC-FS and FC-NF cows had lower machine-harvested milk yields than PC-BW, PC-AW, and NC cows (P ≤ 0.01). We found no differences in responsiveness of calves to behavioural tests, except that NC calves exhibited more solitary play events compared to PC and FC calves in the novel object test (P = 0.002). Overall, our results imply that calves with partial CCC showed low stress responses to debonding, whereas abrupt weaning with a nose-flap during full contact seemed most stressful. Machine-harvested milk yield of FC cows seemed to recover once calves were weaned. More research into strategies to improve the process of debonding is warranted. • Debonding after prolonged cow-calf contact (CCC) may cause distress in cow and calf. • Calves with partial CCC showed minimal stress responses to debonding. • Debonding via nose-flaps negatively impacted calf growth after weaning in full CCC. • Following full CCC, machine-harvested milk yields seemed to recover after weaning. [ABSTRACT FROM AUTHOR]

Early cow-calf separation prevents much of cows' natural maternal behaviour. Early separation is thought to prevent the development of a cow-calf bond. To assess this bond, we measured motivation of dairy cows to reunite with their calf. To vary the degree of bonding, some cows were allowed continued contact with their calf and others were separated from their calf soon after birth, following standard practice on most farms. Among cows allowed continued contact, some were able to suckle their calf and others were prevented from suckling (by covering the cow's udder with an udder net). Cows were habituated to the weighted-gate apparatus before calving by daily training with the (un-weighted) gate. After calving, cow willingness to use the gate was assessed by determining if she would push open the gate to access to her own calf. Testing occurred once daily, with weight on the gate gradually increased. After passing through the gate, the dam's calf-directed behaviour was recorded. Suckled cows pushed a greater maximum weight (45.8 ± 7.8 kg) than separated cows (21.6 ± 6.7 kg) and non-suckled cows (24.3 ± 4.5 kg), with no differences between separated and non-suckled cows. Once reunited, latency to make nose contact and duration of licking did not differ between treatments. We conclude that motivation for calf contact is greater for cows that are suckled. [ABSTRACT FROM AUTHOR]