The Bovine Zero Maze: Development of a novel fear test for cattle

Abstract

Fear tests for cattle are criticized as being 1) designed for animals uncomfortable in open spaces, 2) influenced by previous experience, 3) influenced by context, or 4) subjective. The Elevated Zero Maze (EZM) quantifies fear and anxiety in rodents by exploiting their fear of open spaces and propensity for dark, enclosed spaces. Inversely interpreting the EZM, the Bovine Zero Maze (BZM) was developed to quantify cattle fear and anxiety. Frequency, duration of, and latency to perform steps, escape attempts (EA), direction changes (DC), vocalizations, eliminations, entry into closed/open sections in the BZM were decoded from video recordings. Heifers (n = 14) were re-tested four weeks later. Repeatability was analyzed for both latency to perform and total number of steps, DC, EA, vocalizations, eliminations, standing bouts, and total time spent standing using Pearson correlation coefficients (PROC CORR). Test re-test reliability was evaluated using intraclass correlation coefficients (ICC). Relationships among ADG, EV, and total number and latency to perform steps, EA, DC, vocalizations, eliminations, and standing bouts were analyzed using Pearson correlation coefficients (PROC CORR). Relationships between behavior, minute, and test were analyzed using a Generalized Linear Mixed Model (PROC MIXED) and post hoc analyses were conducted with a Bonferroni adjustment. Total number of steps was the only metric that was repeatable across both tests (R2 = 0.71; P = 0.004) and had moderate reliability (ICC = 0.54). The longer heifers were in the BZM, the frequency of entries into the open and closed sections of the maze and eliminations decreased (all P < 0.01). Heifers vocalized less during the BZM re-test than during the novel BZM test (P = 0.01). Total number of steps made by heifers was impacted by minute (P = 0.006) and heifers tended to take more steps during the second minute of testing (60–120 s) than the seventh minute (P = 0.09). Test × minute affected total number of DC (P < 0.001), however no differences were detected between tests for each minute. Data from this pilot study suggest that behaviors during retesting differ from the novel test and that behaviors change as the test progresses. In addition, the lack of association between behavior in the BZM and EV indicate that the temperament traits evaluated by the BZM may not be related to productivity and may be evaluating different components of temperament than EV.