Transportation of pigs at early ages may result in profit-stripping incidence of mortality and compromised animal welfare due to stress stemming from unfavorable transporting conditions. This project took a four pronged approach to address possible causative relationships of mortality rate, the longer term impact of transportation stress on piglets, and characteristics of the environment within a livestock trailer.

Records from over 7000 loads of weaned and feeder pig transportation loads were analyzed to find the causative factors for mortality during the trip. Weaned pigs had significantly greater death loss during transport than did feeder pigs (0.0333% versus 0.0243%) presumably because of the added stress of weaning at the time of transport. Mortality rates during shipping were lowest during mild weather (59 to 77 F) for both types of pigs. Weaned pigs also were more susceptible to transportation stress under hot weather conditions than feeder pigs. Under hot conditions (> 77 F), longer travel distance resulted in higher mortality rate of weaned pigs with elevated mortality in the longest travel distances for feeder pigs. These results indicate that perhaps extra measures of heat stress reduction may be needed more for weaned pigs than are currently being implemented.

Weaned pigs being exposed to transportation stress tended to have higher death loss the second week after being placed in finishing facilities. During the first week post-transportation mortality rates were 0.050%, 0.050% and 0.045% for cold, mild and hot weather transportation, respectively. The 2-week mortality rates were 0.354%, 0.300% and 0.272% for cold, mild and hot transportation conditions, respectively. This elevation of the second week mortality rates may be due to starve out of pigs that failed to thrive during the first week but lasted into the second week. The cause-effect linkage to transportation environment is not clear cut and other effects are certainly involved.

Trucks hauling weaned pigs were monitored for temperature, humidity and mortality in each compartment as they traveled from Southern Illinois to various locations in Iowa and Northern Illinois. Nearly 80,000 pigs were transported in 78 monitored loads. Trips averaged 484 miles with 8.57 hours of travel time (not including loading and unloading). The overall average of mortality per load was 0.035% with only 28 pigs DOA. The average stocking density in the compartments used was 0.74 ft2/pig. The estimated probability of mortality in any one of the eight compartments in the trailer tended to be numerically higher in the upper deck compartments in summer and higher in the lower deck compartments in winter, though not significant. For cold weather the upper front compartment was significantly warmer than the lower rear two compartments when the stocking density was 0.75 ft2/pig or higher. For mild weather the upper front compartment was significantly warmer than the lower rear compartment when the stocking density was 0.9 ft2/pig. There was no significant difference in compartment temperatures during hot weather at any stocking density.

A 1/7th scale tractor/trailer was placed in a wind tunnel and the interior flow speed and direct was measured with and without the front vents open on the trailer and with and without the internal gating. The side vents were open for all measurements. When front air vents on the trailer were open, air flow tended to occur from the back of the trailer toward the front. Upper compartments tended to have higher air speeds than did lower compartments. When front air vents on the trailer were closed, air flow was more of a mixture with most of the upper compartments having front to rear flow and most of the lower compartments having back to front flow. Using partitions between compartments (gating) within the trailer tended to result in higher air flow speeds within the trailer when the front vents were open. The lower rear compartment (Lower 4) tended to have the lowest or next to lowest air flow rates while the one of the upper front two compartments (Upper 1 & 2) tended to have highest air flow rates, depending on if the front was open (Upper 2 highest) or front vents were closed (Upper 1 highest).