A calm companion lowers fear in groups of dairy cows.

Dairy cows are generally calm and compliant, but some management procedures can make cows fearful or stressed. Not only are fearful cattle a threat to human safety, but fear is also detrimental to animal welfare and productivity. This study aimed to test whether fear in small groups of dairy cattle could be attenuated by the presence of a calm and experienced companion. Twenty-seven dairy cows from a Swedish agricultural school participated in the study. The study included a standardized fear-eliciting stimulus, which was 3 sudden, repetitive openings of a red and white umbrella. Demonstrator cows (n = 9) were selected based on age to ensure that all demonstrators were older than the naïve test cows (n = 18). Of these 9 demonstrator cows, 6 were selected as untrained (i.e., habituated to the presence of the test person) and 3 were selected as trained demonstrators (i.e., additionally habituated to the fear-eliciting stimulus). The remaining 18 test cows comprised 6 test-cow groups of 3 cows each, which were their own controls, resulting in a crossover design; 3 groups were tested with a trained demonstrator first and then with an untrained demonstrator, and vice versa for the other 3 groups, resulting in a total of 12 trials (4 sub-treatments). Response variables were heart rate increase from baseline, behavioral reaction indicative of fear, and latency to resume feeding after exposure to the fear-eliciting stimulus. The study found a calming effect of a trained demonstrator on test cows' heart rate but not on latency to resume feeding or behavioral reaction. Post hoc analyses revealed a carryover effect on latency, indicating that test cows who were accompanied by an untrained demonstrator first had longer latencies than cows in all other sub-treatments. Adding a calm, experienced cow to groups of dairy cattle may mitigate fear and thereby improve welfare and safety.