Does the duration of repeated temporary separation affect welfare in dairy cow-calf contact systems?

Dairy farm calf rearing systems with prolonged cow-calf contact may have benefits such as improved cow and calf health, and better public acceptance of farm practices. However managing cows and calves together can be logistically challenging on modern dairy farms, particularly pasture-based operations. Half-day separation of cows and calves may offer practical benefits compared with full-time contact systems. We predicted that half-day separation could negatively affect cow and calf welfare, compared with separation for milking only. We compared the behaviour of 16 recently calved cows and their calves, separated daily for milking only (MO), or for a half-day (HD) between morning and evening milking (8-10 h of separation per day), over a 10-day period. Linear mixed models and generalised linear mixed models (Poisson regression with random effects) were used to compare the treatments at different times of day. HD calves spent approximately twice as long suckling as MO calves (P = 0.035) before morning milking and after evening milking. HD calves showed a longer latency to lie (analysed using the Goodman-Kruskal gamma test) than MO calves, both when cows left for morning milking (gamma =-0.24, P = 0.045) and when they returned after evening milking (gamma =-0.83, P < 0.001), and had a shorter lying duration in the evening (-375 s, P = 0.009). HD cows avoided nursing 2.9 times more (P = 0.028), and performed approximately 8.5 times more grooming (P = 0.016) and 5.9 times more agonistic behaviours (P < 0.001) than MO cows, when reunited with their calves after evening milking. HD cows also showed more restlessness during evening milking, performing 4.6 times the number of kicks than MO cows (P = 0.035). Results were comparable between treatments (P > 0.05) for milk cortisol concentration, milk yield, time spent ruminating, calf weight gain, cow vocalisations at separation for morning milking, and time taken to separate cows from calves for morning milking. Overall, some potential welfare issues with HD cow-calf separation compared to MO may be calf hunger, cow discomfort when reunited with hungry calves whilst having an empty udder, and cow restlessness at evening milking. Providing HD calves with milk during the period of separation may address these issues, apart from that of cow restlessness at evening milking; however, further research would be needed to confirm this.