Social rank and personality are associated with visit frequency in dairy cows learning to use an automatic milking system

Abstract

Automatic milking systems (AMSs) require cows to perform relatively complicated behaviours: visiting the milking robot voluntarily at appropriate intervals and at a high enough frequency to maintain production. Failure to correctly learn this behaviour can lead to prolonged training for the affected cows, which in turn can result in increased labour, reduced milk yields, and reduced animal welfare. There is currently considerable individual variation between cows in the number of voluntary milking visits achieved per day which may be due to variation in learning ability, amongst other factors. A better understanding of factors influencing dairy cows during conditioning to use an AMS may ensure better adaptation to these systems. To that end, this study investigated the hypothesis that social ranking and measures of personality will influence the ability of cows learning to use AMS. Data were obtained from 30 cows newly transferred to an AMS. The personality attributes of all cows were assayed using two validated tests (human approach, novel object). Principal component analysis revealed two distinct attributes: Boldness and Sociality. In addition, agonistic interactions at the feed face and milking robot were collected over a 3-week period and used to construct a social ranking of the herd using the Elo method. Social ranking and the two personality attributes were used as independent variables in further analysis. Learning was assessed by the following variables, which were included in four separate GLMs as dependent variables; (1) Average voluntary visit frequency weeks zero to two, (2) Average voluntary visit frequency weeks zero to four, (3) Days until the cows’ first voluntary milking, (4) Days until last necessary training session. Cows with higher social rankings had a higher average voluntary visit rate in weeks zero to two and zero to four and a lower latency until their first voluntary milking. Cows that combined a low boldness score with a lower sociality score tended towards a longer latency until their first voluntary milking. We propose that social ranking could play a role in learning success in an AMS context and suggest developing specific training strategies targeting low-ranking cows. Further research is required to fully elucidate the effects of personality attributes on learning success; however, based on the outcomes of the current study, we suggest that investigating strategies for less bold and less social cows may be an important area for future research into improving learning efficacy, productivity, and welfare in this setting.