One of the more disheartening results in pork production is when one or more pigs are dead on arrival at the packing plant. You’ve gotten the pigs all the way through finishing and then you lose a few in transit. While the problem can have many root causes, if you are seeing DOAs that you cannot explain, take a look at the condition and level of bedding in the trailer on the next load of market hogs.

Bedding levels in trailers can have a significant impact on animal losses during transport, according to John McGlone, swine welfare specialist, Texas Tech University.

If you think about weekly marketings, transport issues impact a lot of hogs. Most weeks, more than 2 million market hogs are transported to packing plants, or more than 100 million annually. Most journeys last six hours or less. According to McGlone, some 400,000 pigs per year have a negative welfare experience.

New research, funded by the National Pork Board, suggests that bedding used in transport trailers can adversely affect animal well-being and requires attention. “Most USDA inspectors require bedding to be present on the trailer,” McGlone says. However, bedding requirements vary according to weather conditions. Even though bedding seems harmless, even welfare friendly, using excess bedding can be deadly to pigs when temperatures climb beyond 70° F.

To help define optimum bedding levels when transporting pigs in commercial settings, McGlone and his colleagues recorded a variety of bedding depths present on trailers hauling market-weight pigs, then tallied animal mortalities for each trailer.

Because mortality rates can be influenced by other factors, McGlone’s study also recorded animal-handling intensity by loading crews. He recorded air temperature and humidity levels, total time to load, time en route to the plant as well as waiting time at the plant. 

Certainly many aspects of the transport process can be stressful for pigs. “The load-out and transport processes are full of novel experiences for the pig, including new environments, being mixed with new pigs and thermal discomfort,” says Sherrie Niekamp, National Pork Board’s director of swine welfare. “If the pig is unable to cope with a situation it perceives to be stressful, this can have a negative impact on the pig’s overall well-being.”

McGlone and his associates collected data on 131,000 market-weight hogs transported on 772 trailer loads to determine how varying bedding levels affected the number of dead and non-ambulatory hogs at the plant. Transport took place in a variety of weather conditions.

Transport time varied between 16 and 459 minutes, while wait time at the plant varied from 0 to 198 minutes. Handling intensity at loading ranged from 1 (easy) to 5 (aggressive). Of the 420 finishing sites involved in the study, 43 registered a handling intensity score of 5 at loading. Trailers in the study held an average of 170 pigs. The number of DOAs on trailers arriving at the plant varied from 0 to 8 pigs.

McGlone’s research showed that pigs exposed to aggressive handling at loading produced a DOA and non-ambulatory rate at the plant that was nearly double the average rate seen throughout the study.

The research compared results of transporting pigs with three, six or nine, 50-pound bales of bedding, usually wood shavings or wood chips. Six bales of bedding per trailer typically provide about 1 inch of material on straight-deck trailers 53 feet long by 102 inches wide.

In cold weather there was no economic advantage to increasing bedding over six bales per trailer. When the air temperature during transport was below 10° F and the bedding was fresh and dry, little trouble was encountered.

However, after transport, the bedding typically becomes soaked with urine. If that bedding freezes before a second load is transported, the study suggests you can expect more trouble.

“During very cold weather (below 10° F), we saw an increase in DOAs on the second group of pigs transported on frozen bedding,” McGlone says. “The bedding turns into a big ice cube, and the more bedding, the bigger the ice cube. It’s an important reason to avoid overusing bedding during the winter.”

Besides an increase in DOAs, using excess bedding adds up to substantial cost. (See sidebar.)

During warm weather transport (above 70° F), the study revealed more DOAs when bedding was increased beyond three bales. “During warm weather, bedding and air temperature are additive in terms of increasing the number of dead or non-ambulatory pigs,” according to McGlone's research.

For example, using nine bales of bedding in a trailer during 86° F weather resulted in a DOA rate greater than 1 percent. With three bales, it was 0.5 percent. “Bedding can be deadly to pigs in warm weather,” McGlone says. “The warmer the outside temperature, the worse overuse of bedding will be for the pig’s well-being.”

By focusing on animal handling and transport, the U.S. pork industry has managed to reduce DOAs at packing plants by 42 percent over the past 10 years. Increased floor space during transport and low-stress animal-handling techniques have played important roles.

Addressing bedding levels during transport provides you with another area in your operation that can continue to improve animal well-being as well as economic gains. PK

Big Costs for Excess Bedding

Overusing bedding in transport trailers has a large economic impact to the pork industry, as well as a large impact on the animals’ well-being, according to John McGlone, swine welfare specialist, Texas Tech University. Overusing bedding increases costs for the pork industry in two ways.

McGlone estimates the U.S. pork industry pays $4 million for unnecessary, excess bedding. “In some cases, we simply do not need it and in other cases, such as during warm weather, it actually can increase death loss,” he says.

In addition, McGlone estimates the animal loss due to using too much bedding in temperatures exceeding 85° F at $6.1 million. “That means that the overuse of bedding can potentially cost the industry more than $10 million annually,” McGlone says. “Even if these estimates are high, there’s no doubt that overusing bedding carries a severe economic penalty to the industry and also has a negative impact on animal welfare.”

For more information on loading, transporting and unloading pigs, check out the National Pork Board’s Transport Quality Assurance Plus brochure at