Observations on the effects of non-maternal adult contact on the behavioural patterns of pre-weaned dairy heifers

Context. Dairy calves are often separated from their dams following birth, despite the beneficial effects of early life adult contact on behavioural development across species. Cow-calf contact systems are rare and often difficult to implement in the modern dairy industry. The development of alternative systems offering some of the benefits of adult social contact during early life, such as contact with non-maternal adults, has been limited. Aims. This study explored the behavioural patterns of grouped pre-weaned calves reared with or without non-maternal adult contact, and is the first in a series of studies following the social and behavioural development of experimental calves from the age of 2 weeks to 2 years. Methods. Four groups of 10 calves housed at pasture were studied from 2 to 12 weeks of age. Two groups were housed with three non-maternal dry cows each (+S). Calf behaviour in these groups was compared with that of calves in the remaining two groups, housed without adult contact (-S). Observations were conducted on behaviours including grazing, locomotion and lying, using 5-min scan sampling between morning (0930 hours) and afternoon (1600 hours) milk-feeding on 1 day every second week of the experiment (x(SIC) = 5.9 h of data +/- 0.4 h/group.day). Key results. Few behavioural differences were found between groups. All groups performed mostly lying behaviour in the middle of the day and spent the most time grazing in the afternoon before the evening milk feed. Conclusions. Our results indicated that calves housed at pasture behave according to innate diurnal patterns previously observed in studies of calves housed with the dam, and choose to spend the majority of daylight hours lying or grazing. Being housed with non-maternal adults has few effects on these observed behavioural patterns. Implications. Our study suggests that non-maternal adult contact does not affect the immediate behavioural development of calves housed at pasture. Future research needs to explore longitudinal effects of this contact.