You spend a lot of time and effort to get pigs ready for market, but it can all be wasted if they can’t get off the truck at the packing plant.

Incidents of downer pigs aren’t extraordinarily high on average, but every producer wants his incidence to be as low as possible.       

Beyond the animal welfare responsibility, there’s another sound reason for wanting to reduce the number of downers, since every downed pig takes money out of your pocket. For example, say you have a downer incidence of 0.20 percent and you market 100,000 pigs annually, you’ll loose 200 pigs per year. At a live-hog price of $45 per hundredweight, with pigs averaging 250 pounds, that scenario  would cost you $22,500 a year. Remember that’s using average market weights and prices below current levels.

Cate Dewey, DVM, University of Guelph, found that 0.17 percent of all pigs marketed in Ontario in 2001 were dead on arrival. USDA’s Food Safety and Inspection Service data show the incidence of DOA’s at U.S. slaughter plants in 2002 was 0.26 percent.

There is a difference between downers and fatigued pigs. Downers are generally considered non-ambulatory injured pigs, while fatigued pigs are considered non-ambulatory, non-injured pigs.

Fatigued pigs are classified as out of breath and unable to get off the truck under their own power. However, if they’re allowed time to rest and cool off, they can be slaughtered with no quality degradation (pale, soft and exudative results) to the meat.

“We don’t know the exact prevalence of fatigued pigs,” says Dewey. “My guess is it’s about 0.08 percent of the hogs taken to market.”

Given the fact that the United States slaughtered 103 million hogs last year, it would suggest 82,400 ended up as fatigued. Fatigued pigs present problems for a number of reasons. One is that packing plant procedures to handle such pigs vary greatly.

“Some plants might unload fatigued pigs with a skid loader and set them aside for a period of time,” says Larry Rueff, DVM, Greenburg, Ind. “ If the pigs are found to be okay after a period of rest they will be moved to the kill floor.”  Other packers may not take this approach, and simply label the pig as a downer, which means you would be paid little or nothing for it. “Federal inspection requirements may regulate what can be done in some cases,” he adds.

In Canada, there is a new law that treats all pigs that are unable to exit the trailer on their own as downers. This can be costly, as some of those pigs could recover and receive normal treatment and payment. No such law exists in the United States to date.

Causes of fatigued pigs seem to be closely related to causes of downers. If a pig is fatigued during the loading process and it gets on the truck, chances of it dying in transit increase significantly.

University of Illinois research shows there is substantial variation in fatigued pigs. In one study of 48 loads, 30 percent had no downers. However, 60 percent of the downers were concentrated on 20 percent of the loads.

One explanation for this could be the people handling the pigs. More data from Illinois shows that variation in fatigued pigs among farms with the same genetics, similar facility design and using the same trucks and truckers was three fold. By the same token, the range between truckers transporting pigs from the same farm on the same day, using the same trailer design was three fold as well.

There is a direct correlation to the use of electric prods and the incidence of fatigued pigs, says Dewey.  Another factor that may increase the incidence of fatigued pigs is high-lean genetics. Michigan State University research suggests there may be a defect in the stress gene that leads to a stress-related response, even if the gene is not present.

It’s also important for you to monitor your trucker. National Pork Board’s Trucker Quality Assurance is an education program that teaches truckers proper animal- handling methods. It’s been shown to reduce the number of stressed pigs arriving at plants. It would be wise to make sure you only ship pigs with TQA-certified truckers.

“Trucker education programs have increased awareness of animal-handling procedures and the relationship to downed pigs. Overall trucker behavior has probably changed as well,” says Dewey.

Conditions within the truck also play a role. The truck or trailer should have clean, dry floors or include shavings or sawdust on the floors. Keep in mind that not all trucks are the same inside. Work with your trucker to determine the proper sized load, taking into consideration the size and type of truck, as well as the size and weight of your pigs. Remember, certain areas on board (like the belly of a three-tiered trailer) will have less ventilation than other areas.

Some European studies show that the trucker’s driving also has an impact. Making sharp turns and sudden stops can make pigs carsick. However, if the trucking is done primarily on Interstates, as is the case in the United States, driving style is less of an issue.

Climate and season have an impact on fatigued pigs. “Temperature and humidity are certainly factors. Producers need to think about managing pigs differently during hot periods,” says Dewey. For example, sort and load pigs early in the morning or at night, to avoid the task during the day’s heat.

As for humidity, it affects pigs largely because they don’t sweat, making it even harder for pigs to cool off when the heat and humidity are both high. (For a heat index related to pigs, see sidebar.)

Citing seasonal patterns, Dewey says the incidence of downers rises to about 0.36 percent in the summer months; is around 0.13 percent in the spring and fall; and drops to 0.11 percent in the winter. However, those same patterns have not been shown in the United States, says Mike Ellis, Univeristy of Illinois.

Since you can’t control the weather, you’ll have to turn to management to keep pigs cool in the summer. Luckily, there are some things you can do.

Before loading pigs you should take them off feed for at least four hours to reduce vomiting, says Dewey.

“You need to review your handling system to make it as safe, efficient and stress-free as possible,” says Rueff. “This includes making sure loading chutes are wide enough to prevent two pigs from becoming wedged and that ramps and flooring aren’t slick.”

University of Illinois research shows that aisle widths of 3 feet will reduce the incidence of wedging and therefore downers, when moving groups of three to five pigs.  Thorough lighting is another important factor; this means checking for shadows and other visual factors that could spook pigs during loading.

The loading ramp’s angle is crucial. Pigs don’t like to go up ramps of 30 degrees or greater; if they are forced to, their body temperature and heart rate increase. It usually takes an electric prod to get pigs to climb a 30-degree ramp, points out Dewey, which adds to the pig’s stress. If that same pig gets hot during transport, it could die before reaching the packing plant. She recommends loading ramp angles to be set at 26 degrees or less.

Other tips to reduce stress while loading hogs include walking the pens once a day to get the pigs used to human interaction.          

“About 80 percent of market-related deaths occur when pigs are on the truck,” says Dewey. “In the summer you should plan to put fewer pigs on the truck. You want more air movement around the pigs’ bodies and allowing more space provides that.”

Some operations in Europe have put fans on the trucks. Another idea is to install spray-coolers. Dewey says pigs will stay fairly cool when the truck is moving, but they get hot quickly when it stops. If you and your trucker can address this issue and spray hogs while the truck is stopped it could help. Packing plant personnel should arrange loads so truckers don’t have to wait long to unload pigs.

Packers should have some sort of cooling system on site, whether it involves misters, fans or a simple hose during the summer to accommodate the pigs as soon as they come off the truck. Other things packers can do to prevent downers include penning pigs by load, so there is less remixing and fighting before slaughter.

“Packers need to ensure that they have state-of-the-art techniques and technology during unloading, tattooing and weighing pigs, to make sure there’s no undue stress on the pigs,” says Rueff. “The goal is to make it a leisurely walk to the kill floor, not a stressed one.”

While the incidence of downed or fatigued pigs is not rampant in the U.S. pork industry, each case takes money out of your pocket and raises pork quality concerns, so it makes sense to minimize cases.

Then there’s the image factor. “Reducing the number of downers is more important today, because the industry is more aware that the public is watching,” says Rueff. “Consumers and buyers are more likely to be watching to make sure animals are raised and slaughtered in a humane fashion than ever before.” 

Number of Pigs Getting Down

Downers and pigs that are dead on arrival (DOA) at the packing plant are at least an occasional problem for every producer. But what is the normal level for downers and DOA’s?

The incidence of downer pigs in field studies has ranged from as low as 0.1 percent to as high 0.9
percent, with total transport losses (DOAs + Downers) varying from less than 0.4 percent to as high as 1.1 percent. 

If a producer has total losses higher than 0.6 percent on average, then some action should be taken to reduce the incidence.