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A description of mount
behaviour during the Buller Steer Syndrome in a western Canadian feedlot
J.L. Clavelle
University of Saskatchewan,
Saskatoon, Canada
The Buller Steer Syndrome is an aberrant behaviour characterized by the persistent and excessive mounting of one steer (the buller) by several of its pen mates (riders). Fourteen steer pens (containing a total of 2919 steers; mean group size 209), at a commercial beef feedlot were included in the study. Twelve pens were each observed once per daylight hour, for a 4-min period. Each pen was assessed for the presence of a ‘Suspect’ Buller (SB) (a steer that might become a Buller) or a Buller steer, according to pre-determined SB and Buller criteria. To be considered an SB it had to receive at least 3 mounts and 5 chin rests, and be followed by 3 riders throughout the duration of the 4-min period. To be considered a Buller it had to receive at least 7 mounts and 10 chin rests and be followed by 7 riders throughout the duration of the 4-min period. Once a buller was identified, observations of other steer pens ended. Observations were continuously recorded until sunset, or until buller activity had ended (buller received no mounts for a period of 20-min), or until feedlot personnel removed the buller.
Eleven steers were identified that met Buller criteria. Bullers on average received a total of 61 mounts/hr (range 43-114 mounts/hr) and an average of 149 mounts total (range 36-353). Bullers were followed by an average maximum of 11 riders (7-18). Results were divided into 10-min periods. The maximum number of mounts each buller received varied considerably between bullers (12-34 mounts/10-min). Mount frequency was observed to be ‘episodic’, with periods of high intensity followed by periods where mount frequency was relatively low. Buller activity for six of the 11 bullers ended but then resumed later that day or during subsequent days. Of the 11 bullers, feedlot personnel removed only four. Buller activity for the remaining seven bullers had ended by the time feedlot personnel arrived at the pen. Bullers were observed during all times of day. We conclude that a buller’s identification and subsequent removal from the pen is dependent on the time at which feedlot employees enter the pen relative to peaks in buller activity.