Producers and packers would like to reduce dead and down market pigs during transportation for economic and welfare reasons. Transport losses may be due to pig genetics, management before, during and after transportation, handling and environmental factors to identify a few. Environmental factors during transportation can be partly controlled whereas some of the components of environment cannot be controlled by human effort. Temperature, humidity, ventilation and air speed in close contact with pigs, termed as the micro environment, play a crucial role that can impact pork quality and  transport losses.. There are few peer reviewed  studies conducted in this area focusing on the microenvironment inside the trailer. Because transported pigs are in close contact with bedding, the type, quality and level of bedding may be important factors associated with the rate of dead and down market pigs.
The objective of this study was to establish the level of bedding to be used while transporting market pigs from finishing sites to packing plants in the U.S. over different seasons and weather conditions. This work is a challenge due to the large sample size needed and the need for study personnel at both the farm and plant during data collection.

The study was divided into three parts; winter (January and February), mild (March and May) and warm summer months (June and July) in the mid-west region of U.S. (Iowa, Minnesota and Missouri). Three levels of bedding; low (3 bales), medium (6 bales) and high (12 bales) were assigned randomly to the trailers within each season. Only medium and heavy levels of bedding were used during winter; low, medium and heavy during mild and only low and medium bedding levels were evaluated during the summer period.
This study was conducted in field while market pigs were transported from finishing sites to the packing plants. Variables measured at the finishing site include bedding information, trailer information, handling method, devices and intensity, information on farm design and management, and external environmental condition. Sensors set to record relative humidity (RH) and temperatures every 5-minute during loading, transit, waiting at the farm and unloading were installed in selected trailers in four compartments; top front, top rear, bottom front and bottom rear. Surface skin temperatures on the pig’s flank/side of 10 randomly selected pigs (5 of first 50 and 5 of last 50 pigs loaded into the trailer) in each load were also taken with an infrared laser thermometer (Extech model # 42570) with a sensitivity of 0.1 °F. At the packing plants, weather information, handling methods, intensity and devices, dead on arrival, non-ambulatory and total dead and down information were collected.
Major findings and recommendations of the study based on the total loss of the pigs include:
1. During cold weather (<32 °F), there was no significant bedding effect, so there is no advantage of added bedding beyond 6 bales/trailer;
2. Similarly, during mild weather (32-70 °F), there was no significant bedding effect, so there was no advantage of added bedding beyond 3 bales/trailer;
3. But during warm weather (<70 °F), added bedding had a negative effect on dead on arrival beyond 3 bales/trailer;
4. Pig surface temperature increased with air temperature and during warm weather increased surface temperature predicts increased DOA.

Suggested recommendations in bedding level use:
1. During cold weather, a maximum of 6 bales of bedding per trailer is recommended and during mild weather 3 bales per trailer is recommended. During warm weather no more than 3 bales of bedding per trailer is recommended.
2. Surface temperature can be used as non-invasive method to assess pig welfare and predict dead on arrival of pigs during warm weather.
Further research is required to determine if lower amount of bedding is required during winter (less than 6 bales) and warm weather (less than 3 bales or no bedding). Also, boarding and misting requirements need to be determined to improve internal trailer environment and welfare of pigs during transportation.

For further information contact: John McGlone (email: [email protected]; Phone: 806-742-2805, ext. 246; Fax: 806-742-4003)