Abstract
Dairy cattle experience a variety of stressors associated with routine farm practices, including injections, pen movements, regrouping, and artificial insemination. The primary objective of this study was to assess ear position (categorized according to 5 positions) and body movement responses of heifers during their first experience of artificial insemination, in comparison with responses during baseline observations before and after this procedure. A secondary objective was to test whether heifers exposed to positive reinforcement training (PRT) responded differently to this procedure. We tested 12 heifers (13 ± 0.7 mo. old); 7 were trained using PRT (as part of another study) and 5 had no experience with PRT. Ear axial and ear forward positions were more frequent during observations before and after artificial insemination relative to during artificial insemination (4.57 ± 0.82 vs. 0.31 ± 0.82 times/period, and 3.45 ± 0.51 vs. 0.50 ± 0.51 times/period, respectively). Backward pinned ear position was observed less frequently before and after versus during artificial insemination (0.12 ± 0.76 vs. 3.76 ± 0.76 times/period). We found no effect of period relative to artificial insemination on any of the 4 body movements assessed (leaning forward, backward, and steps taken with front legs and back legs).We found an effect of PRT on forward ear position (1.00 ± 0.51 times/PRT group vs. 2.95 ± 0.60 times/control group), and found that control heifers leaned forward and took more steps with their front legs than did PRT heifers (0.93 ± 0.57 times/PRT group vs. 3.55 ± 0.67 times/control group and 1.29 ± 0.68 times/PRT group vs. 3.85 ± 0.81 times/control group). We conclude that heifers experiencing artificial insemination for the first time express distinct ear positions that are consistent with responses to a negative emotional state. Further work is required to validate these responses and to determine the extent that they can be used to assess affective responses to this and other procedures.