Add this to the potential criteria for sorting incoming stocker calves based on performance potential and health risk: calf location in the loaded trailer.

“Our current project reveals that the environment within a commercial transport carrier is not likely homogeneous. And, cattle position within the transport vehicle may result in differing health and performance outcomes,” say researchers at Kansas State University (KSU).

In this unique study spanning two years (May 2006 to May 2008), KSU researchers looked at how location within the trailers impacted the health and performance of 21 loads of calves assembled in the Southeast, commingled in Tennessee and shipped to the KSU Beef Stocker Research Unit west of Manhattan. Specifically, KSU researchers—Dale Blasi, Mark Epp and Brad White, DVM—looked at health and performance differences during 45-60 days of backgrounding ahead of pasture turn-out.

Trailer sections were identified as: bottom deck rear (BDB), bottom deck front (BDF), bottom deck (bottom deck forward and back combined, BOT), rear on top (ROT), bottom deck nose (NOB), nose on top deck (NOT), rear on bottom (ROB), top deck back (TDB), top deck forward (TDF), and top deck (top deck back and forward combined, TOP).

Approximately 24 hours post-arrival, cattle were processed with standard health protocols including castration for bulls, metaphylaxis, modified-live and viral vaccines. Vaccinations were boostered, and individual animal weights were recorded between 10 and 16 days after arrival for each load. Cattle were fed a total mixed ration twice a day that included a mixture of prairie hay, alfalfa, wet gluten feed, and cracked corn. Calves were fed for approximately 6 weeks; just prior to exit from the facility, each animal was individually weighed.

According to the results:

  • Cattle in the middle section were significantly more likely to be treated at least once than cattle in the most forward sections.
  • The least squares mean rate of gain (Average Daily Gain-ADG) from arrival to reweigh for cattle in the rear section (3.8 lbs./head daily) was lower than that for calves housed in the front section (4.2 lbs./head daily). Cattle in the middle section also tended to have lower least squares mean ADG during this period (4.0 lbs./head daily) than cattle in the front section.
  • The relationship with this short-term gain was further explored when the rear of the truck (ROT, ROB) was compared with the rest of the vehicle. Cattle in the two rear truck sections had lower ADG relative to cattle in the middle and forward sections of the truck.
According to the researchers, “One hypothesis to explain this finding is that potentially toxic fumes from the transport vehicle move behind the vehicle because of airflow currents and enter the rear of the truck, exposing these calves to lower quality air first. This could lead to short-term mechanical or physiological insults that limit short-term ADG. This hypothesis may be supported by the fact that one of the few associations between health outcomes and location on the truck was identified between cattle in the most forward sections (NOT, NOB) when compared with cattle in the middle (BDF, BDR, BOT, TOP, TDF, TDR) or rear (ROT, ROB) compartments.

“In many transport vehicles, the front of the first two sections is solid or directly behind the cab of the truck and thus protected from direct intake of exhaust. If airflow from the exhaust enters the trailer from the rear and sides of the truck, the most forward sections would tend to be somewhat protected from this effect.”

For more information, see www.oznet.ksu.edu/library/lvstk2/SRP1010.pdf