Tips For Evaluating Your Implant Program

Side Effects: Buller Syndrome

The buller syndrome is an economically significant, abnormal behavioral trait of feedlot steers. It has an increasing incidence about which comparatively little is known. The syndrome is characterized by an expression of female sexuality by the buller steer, which becomes sexually attractive to some of its penmates (riders). Riders will persistently follow and repeatedly mount the buller until it becomes so physically exhausted that it can no longer stand.

Even though the syndrome has been known to exist for several years, it has only recently been described to be of significant monetary importance. The current changes in the cost and price structure of the cattle feeding industry, together with improved management, have emphasized the importance of conditions, such as the buller syndrome, which are responsible for a loss other than that associated with infectious disease or death.

The fairly intangible monetary loss involved with each buller has been estimated at $23.68. This loss has been attributed to injuries, reduction in live weight gains, and occasional deaths. The cost of treating the traumatic lesions also should be considered. Treatment costs should include not only medical expenses but also the labor and record keeping involved when the affected animal is removed from its pen, maintained in isolation facilities until recovery, then returned to its original pen.

The cause of the buller syndrome is unknown, but practical field observations have led to the consideration of several predisposing factors–mainly weather, management procedures, and anabolic hormone implants. The course of the syndrome is thought to involve increased blood concentration of estrogenic hormone, expressed by mounting behavior.1

Factors Associated with Bulling

  • Stress factors
    • Age at castration
    • Disease or injury
    • Pen density
    • Processing
    • Time of processing
    • Ration changes
    • Transportation
    • Weather changes
  • Seasonal influences
  • Estrogenic compounds
  • Growth stimulants
  • Plant estrogens

Economic Considerations

  • Increased labor costs
  • Increased management costs
  • Increased susceptibility to disease
  • Physical injury
  • Property damage
  • Maintenance of isolation pens
  • Reduced carcass value
  • Occasional death

Feedyard managers who recognize the impact of the buller syndrome will be better able to estimate its cost and make management decisions to help control it.

1 Irwin MR, Melendy DR, Amoss MS, Hutcheson DP. Roles of predisposing factors and gonadal hormones in the buller syndrome of feedlot steers. JAVMA 174;4: 367-370, 1979.