Dairy cows housed both full- and part-time with their calves form strong maternal bonds

Dairy cow and calf are typically separated shortly after calving preventing the formation of a maternal -filial bond. To allow some cow -calf contact, part-time contact during the first weeks is thought to be a feasible solution, but it is unknown if it weakens maternal bond, i.e., if maternal motivation is lower. This study aimed to investigate how different amounts of calf contact (full-time, part-time, and no contact) affect cows' maternal motivation. Using pneumatic push gates, we assessed cows' motivation to access their own calf using the maximum price paid (MPP) method. To mitigate frustration at high prices, cows could also access an unfamiliar calf at a constant low price. We expected that cows would access the unfamiliar calf when reaching the maximum price that they were motivated to pay to access their own calf. Following 48 h in a calving pen, cow -calf pairs were allocated to three different treatments: full-time (23 h contact/d, 28 pairs), part-time (10 h contact/d, 27 pairs), and no contact (0 h contact/d, 26 pairs). Approximately 40 d after calving, cows were trained to pass through each of two push gates: one leading to their own and one leading to an unfamiliar calf. The weight on the gate leading to the cows' own calf increased following each passing, while the gate leading to the unfamiliar calf remained light. Cows were tested once daily, until they failed to pass through the gate leading to their own calf on two consecutive days. MPP was analysed using a Cox's proportional hazards mixed effects model. Fewer nocontact cows than full- and part-time cows fulfilled the learning criteria. Furthermore, no -contact cows paid a lower maximum price compared to the two contact treatments, while the MPP of full- and part-time cows did not differ. Most cows remained in the start box if they did not pass the gate to their own calf, indicating that an unfamiliar calf could not substitute for their own calf at high prices. We conclude that cows with part-time calf contact form a maternal bond of similar strength to cows with full-time calf contact. Additionally, cows separated from their calf at 48 h after calving have a weaker maternal motivation at 40 days postpartum.