Buller steer syndrome review

The bullet steer syndrome is found among confined and pasture-kept cattle. The buller behavior occurs when a steer is repeatedly mounted ('buller') and ridden by its pen mates ('rider') until it is injured or killed. The usual practice is to remove the animal being ridden. The ridden animals are typically grouped together in a 'buller' pen where little or no mounting is observed. The bullet steer syndrome, in today's dollars is estimated at US $70 per steer and thus represents a significant economic loss. Factors associated with an increase in the rate of bulling include: submissive behavior, pheromones, warm weather, large group sizes (over 200-250 head per pen) and other stressful events (mixing, handling, temperature, dust). Bullet steer physiology has been studied, with few concrete conclusions. Exogenous estrogen may increase and androgens may decrease the behavior. The vomeronasal organ was not found to be involved in the behavior since lesions to this secondary olfactory organ did not influence bulling rates. A concerted effort is needed to systematically study this problem for economic and welfare reasons.