Better handling at the farm and attention to detail in loading and hauling has improved the process of shipping hogs to slaughter.

But a University of Illinois research project is exposing one gap in that process: the shortcomings of the transport vehicles in providing a suitable environment for the journey to the packing plant under all weather conditions.

The University of Illinois project, which was funded by the National Pork Board, represents a collaboration between animal scientists, agricultural engineers and a leading production system (The Maschhoffs) and was led by Professor Mike Ellis. University of Illinois graduate research assistant Chad Pilcher outlined the series of challenges and some potential solutions at the Swine Handling and Transport Forum in Des Moines, IA, in June.

A double-deck, aluminum, punched-side livestock trailer typically used to haul hogs was studied. The trailer was divided into 11 compartments to evaluate environmental conditions on hogs hauled from the farm to the packing plant in a span of about three hours.

A total of 20 trailer loads of 156 market hogs, averaging 290 lb., were monitored. All 11 compartments were fitted with monitoring devices to measure temperature, relative humidity, carbon dioxide and airspeed.

Not surprisingly, trailers were hot and humid in summer shipments; however, the variation in temperature and humidity between compartments was relatively small.

In contrast, the variation in temperature between compartments in the winter was large, with the temperature in the rear compartments being close to freezing, while in the front compartments the temperatures were above 50°F for most of the journey.

Generally, throughout the study period, results indicated that air velocity or ventilation was fairly good in the middle compartments, and poor or virtually nonexistent in the front compartments of the trailer, Pilcher says.

Both temperature and humidity levels rose quite rapidly in all seasons when the trailer was stationary.

The major conclusions were:

  • There was extreme variation in environmental conditions on transport trailers both between seasons and between individual compartments on the same trailer load of pigs.

  • The times of greatest extremes and changes in temperature were when the trailer was stationary.

  • Temperatures were generally higher in the front compartments of the trailer.

Pilcher says the environmental issues cited are potentially predisposing factors for transport losses. However, he reports no pigs became non-ambulatory or died during the study.

Their recommendations:

  • Trailers should be designed to minimize variation in environmental conditions between compartments.

  • Trailers should have a “ventilation control system” to cope with environmental variations.

Until those changes can be made in manufacture of livestock trailers, Pilcher suggests:

  • Minimize the amount of time trailers are loaded and stationary. “Once pigs are loaded at the farm, get moving as quickly as possible and keep the vehicle moving,” he says.

  • Design facilities for efficient loading and unloading. Having pigs presorted before load out can help.

  • Utilize large external fans while the truck is stationary.

  • Work with your packer in scheduling times to reduce waiting at the slaughterhouse.

“We have loads of hogs that are transported from the southern United States to the northern United States, and those pigs encounter quite varying conditions. With the current design of trailers, the only way to adjust the ventilation openings is by the trucker when the trailer is stationary,” Pilcher says. To help this situation, Pilcher urges the pork industry to scientifically validate current Transport Quality Assurance guidelines for trailers to recognize the need to improve environmental conditions for the pigs.

He also suggests there is a need to develop a system that ideally, automatically changes sidewall openings.

Livestock trailers may also need to be redesigned to improve ventilation in the front and rear sections of the trailer that could have hot and cold areas.

Another future design change could include the installation of ventilation fans in the front end wall of the trailer to pull cool air across the pigs when the truck is stationary.