Behavioral Fear Response to a Novel or Human Stimuli in Barrows Selected for Feed Efficiency
The objective of this study was to relate fear behaviors to feed efficiency gains through the human approach and novel object tests. Eighty Yorkshire barrows divergently selected for feed efficiency were tested using the human approach and novel object tests to evaluate fear behavior. Testing occurred over four consecutive weeks between 1300 and 1700 h. Barrows were tested individually within a 4.9 x 2.4 m test arena. Live observations were collected continuously by one observer. Data was collected on latency and total number of urinations, defecations, and human/cone touches. All data is presented descriptively. During both the human approach and novel object tests more feed efficient, low residual feed intake (LRFI) barrows took longer to approach the human or cone than the lessfeed efficient, high residual feed intake (HRFI) barrows. Once the pig made contact with the novel stimuli, total number of stimuli contacts were similar between genetic lines. During the human approach test, HRFI line barrows took less time to urinate but longer to first defecate compared to pigs from the LRFI line. During the novel object test, HRFI line barrows took more time to first urinate but less time to first defecate compared to pigs from the LRFI line. Throughout both tests, pigs eliminated a similar number of times. In conclusion, barrows of the LRFI line took longer to approach the human and cone compared to HRFI line barrows but once they made contact with the novel stimuli, interactions were similar between genetic lines.