Prevalence of traumatic events for each combination of breed and trailer type. There was a significant interaction between trailer type and cattle breed, whereby Holstein cattle hauled in fat/feeder combination trailers experienced higher prevalence of traumatic events than their beef counterparts. 1Fat/feeder combo trailers are those which are used to haul both feeder calves and finished beef cattle. Fat trailers are usually used to haul finished cattle only. The differences between these types of trailers include the presence or absence of a “jail” or “doghouse” in the upper rear compartment of the trailer, used to contain very small calves (present in fat/feeder combo trailers, Beef Quality Assurance, 2006), the presence of a small compartment in the nose of the trailer, used as a counter-balance (also present in fat/feeder combo trailers), and the clearance height of the entrance into the “belly”, or lower compartment of the trailer (approximately 5–8cm shorter in fat/feeder combo trailers). Either type of trailer can have a slide-in or fold-up ramp leading into the upper deck compartment.