Editor’s note: John McGlone, swine specialist, TexasTechUniversity, conducted an extensive, multi-disciplinary study on dead and fatigued pigs. Those findings are the basis for the four-part series presented in Pork magazine.

Stress has an additive effect on pigs.

The stress of being moved at the farm, during loading, transport, unloading, as well as the plant experience, all add up in the pig’s mind and body. If you can examine each element and reduce the stress level, your total dead- and fatigued-pig rate also will decline.

The transportation experience is new to pigs headed to market. Even if they were transported earlier in the production cycle, it is a different scenario. The animals are larger, the move will likely take place during a different season, with a different truck/trailer and driver. 

Several factors will influence the marketing-transport experience and stress response. Such things as the new social group formed in each truck compartment; the flooring, temperature and humidity; the new lighting and smells. The actual riding experience (sharp turns, rough roads, abrupt stops and so forth) will add to pigs’ stress levels. A combination of “truck factors” will cause variation among drivers, but in the end, the driver has a significant impact on dead- and fatigued-pig rates. (See chart.)


The data represent multiple loads of market hogs from 38 drivers that moved a total of more than 1 million pigs.  Drivers’ dead- and fatigued-pig rates ranged from 0.02 percent to 1.4 percent.

The causative factors are found in two general areas: truck set-up and driver behavior.

For pigs, the environmental conditions inside a truck can range from comfortable to deadly. That’s why it’s so important to prepare a truck to minimize the negative effects and reduce dead and fatigued pigs. Drivers have three tools to manage the trailer environment: bedding, side slats and misters. The key is to mitigate low and high temperature extremes that can cause significant problems for pigs. (See chart below.)

Pigs are transported in all seasons and in a range of environmental conditions. The outside environment may be hot, warm, cool or cold; it could be dry or humid; and the weather can be constant or changing. A knowledgeable driver can anticipate environmental conditions and minimize the risks to pigs. This is especially critical for long hauls and transport across varying geographic areas.


Generally, warm weather increases the rate of dead pigs on arrival at the packing plant and cold weather increases fatigued-pig rates.

Shown here are air-temperature effects on the rate of dead pigs arriving at the plant per week. Note the increase when the air temperature moves above 75°F. This data represents about 2 million pigs arriving at a single, large Midwestern packing plant.

It’s important to understand that when a trailer is full of pigs, the conditions inside it are different than outdoor conditions. When a truck stops, temperatures inside the trailer are always warmer than outside—and those temperatures rise the longer the truck is stopped. Drivers should avoid unnecessary stops. Stopping for more than 30 minutes, with no cooling can be deadly in any season.

The second important environmental variable is humidity inside the trailer. Again, it’s always high when a truck is stopped and the trailer has a full load. Pigs breathe out moist air and urinate which adds water and ammonia to the air.

Always assume it’s humid in the trailer regardless of outdoor conditions, which means outdoor temperature changes have larger effects inside the trailer. For example, if it’s 85°F outside, that’s not a particularly deadly temperature for pigs. However, inside a stopped trailer, it may be 95°F and 95 percent relative humidity, which puts pigs at risk of death.

Drivers should be alert to potential problems when the air temperature exceeds 75°F. That’s when side slats come into play. (See table on page 20.) If the weather changes, it’s important to stop the truck and make adjustments for pig comfort.

To cool pigs, keep the truck moving or, if possible, place the truck in front of a bank of fans to cool pigs. Water misters can be used, but the truck must start to move shortly thereafter or the added humidity will only add to heat-stress levels.

Bedding should be used to prevent pigs from slipping or falling and to provide comfort for pigs in cold weather. Don’t make absolute bedding requirements; instead, adopt a performance standard that requires bedding and floor surfaces to be generally dry when the truck arrives at the plant. Keeping bedding dry can cut the dead-on-arrival rate by 14 percent compared to either no bedding or when the bedding is wet. Thus, if the bedding is wet when pigs reach the plant, it has the same effect as having none at all.

The type of truck is another factor that can influence dead- and fatigued-pig rates. Trailers are generally either straight-deck or pot-belly.

Pot-belly trucks vary in that some are used for both cattle and pigs, and some are designed more for pigs. Some require pigs to go up and down ramps within the truck.

On average, pot-belly trucks have a 5 percent higher combined dead- and fatigued-pig rate than straight-deck trucks, but that is driven by a higher dead-pig rate. Pot-belly trucks actually tend to have a lower fatigued-pig rate than straight-deck trucks. But, they do have a slightly higher rate of injured pigs.

It is important to note that some truck drivers using pot-belly trailers have low dead- and fatigued-pig rates. In reality, the differences between pot-belly and straight-deck trucks is much smaller than the variations related to drivers.

Regardless of the type of truck, drivers should be trained and certified through the National Pork Board’s Truck Quality Assurance program.

You should insist on farm-specific truck and trailer requirements, including stop-time limits and contingency plans if delayed; bedding requirements; pig-space requirements in each trailer compartment; side-slat requirements; and policies for misting or wetting pigs while on the trailer. Of course, producer-owners should monitor a driver’s dead- and fatigued-pig rates and implement improvements as warranted.

Some final transport-related areas to think about include:

  • Be sure drivers are TQA certified.
  • Never use electric prods, instead, use flags, capes and paddles to move pigs.
  • Ensure that only trained and qualified drivers transport pigs using pot-belly trucks.
  • Packers should score truck drivers and provide regular feedback on dead- and fatigued-pig rates.
  • Be sure that your drivers understand operating procedures for cold weather, warm weather and changing weather.
  • Always use bedding; use more during extreme cold weather.

While stress has an additive effect, you can minimize or even subtract from your dead- and fatigued-pig rates with the proper transport techniques.

By John McGlone, swine specialist, Texas  TechUniversity

Editor’s note: This is third in a four-part series that will look at the fatigued-pig issue on the farm, in transport and at the slaughter plant.