Pregnant cattle associations and links to maternal reciprocity

• Correlations between cattle social associations and postpartum age were explored.
• Maternal status is an important determinant of association preference.
• Association preferences change immediately post-partum.
• Maternal cows preferentially associate with cows having calves of a similar age.
• Offspring provides a motivation for reciprocity.

Cattle are a highly gregarious species that form strong social connections. Social support following calving serves to increase offspring survival and conception rates for the following breeding season. It has been shown that cattle change their association preferences following calving, but the correlation between social association and postpartum age class has not been explored. This study investigated the effect of postpartum age on association strength based on the amount of time pairs of individuals spent within close proximity as recorded by proximity logging collars. The associations of 58 mixed breed cattle were recorded over an 11 week period and associations analyzed within and between three maternal classes: maternal (calved prior to the beginning of the trial), pregnant and calved during the trial. There was a clear distinction in the association preferences between the maternal and pregnant cows: both cow classes associated more within their own maternal status than between statuses (maternal 181.47s, pregnant 141.48s, between groups 91.62s, P < 0.001). Network analyzes showed both between and within group preferences for the two groups, with some individuals playing a prominent social role in connecting the groups together. The cows that calved during the study showed an immediate change in association preference from the pregnant to the maternal group following parturition. The effect of this was correlated with age of calf; newly maternal cows preferentially associated with cows that had calves of a similar age. This study demonstrates that maternal status is an important determinant of association preference. The change in association patterns once a pregnant cow calves and the strong dyadic relationships between newly calved cows supports the notion that an offspring at foot might provide a motivation for reciprocity.