Cattle transportation is more complex than loading them up and moving them out.
Feedlot cattle spend more than 65 million hours in transport annually in Canada.
During those trailer-bound hours the average animal shrinks 1.7 percent, or 8.5 kilograms, during journeys of four hours or less. That shrink increases to 4.6 percent, or 23 kg, when the trip lasts longer.
Al Schaefer of Agriculture Canada in Lacombe, Alta., says this loss is real money, not gastrointestinal fluid or urine.
“These are water losses but they come from the muscle mass. That is expensive water that you can’t just put back very easily,” he said in a speech to colleagues at a recent Canadian Society of Animal Science conference in Saskatoon.
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On average, a 500 kg animal will lose between $12 and $41 in value during transport to slaughter. Should the trip be too stressful for the animal and it ends up as a dark cutter, the carcass is discounted $200-$300 at the packing plant.
Transportation is blamed for half of the downgraded animals due to dark, firm and dry meat quality.
“We have a lot of work to do on our trucks and our knowledge of how transportation affects livestock,” Schaefer said.
“Time in the truck, the driver’s abilities, the weather, the exhaust, the trailer, the road surface, the conditioning prior to loading – it is complex and it is costing the industry a heck of a lot of money, and it is one of those areas that people just don’t think enough about,” he said.
Malcolm Mitchell of Scotland’s Roslin Institute would agree.
His work has been the basis for European Union regulations for animal hauling and he said “many things may be blamed for animal losses in transport. Even more losses in meat quality are blamed on something else entirely. In fact, these were problems associated with animal stress during transport.”
Peter Kettleswell, a colleague of Mitchell’s, is an agricultural engineer at Silsoe Institute north of London, England.
He uses a specially designed truck and trailer with built-in monitoring equipment to study livestock in transit.
“We can monitor deep body temperatures, stress levels, ambient temperatures, wind speeds internally and externally, carbon dioxide levels. If it is happening to animals, we know about it,” Kettleswell said while presenting his research at the Saskatoon event.
“Trailer design has significant effects on livestock. Wind doesn’t go where you think it will. Temperatures on a cold day can range by 40 degrees (Celsius) in the same load of animals. You can kill them with heat in one part of a load and freeze them to death in another…. And moisture is more important than almost any other single factor. So wind and ventilation are critical. This is a super-confined barn on wheels.”
Kettleswell found that air enters from the rear of the trailer and exits from the sides at the front.
A vacuum forms at the front of the trailer by the forward motion of the vehicle and is stronger than any wind force trying to come into the front vents. The hottest part of the load is always the top, forward section, back slightly from the very front as air is drawn through the load of animals and exits there.
“You can fit the truck with all sorts of dams and air devices. It won’t change this basic fact,” he said.
In a recent Schaefer study, a standard load of 455 kg calves was hauled between Kamloops, B.C., and Lacombe, Alta. Depending on where the animals were located in the trailer, they lost between 7.3 and 10.1 percent of body weight.
The highest losses were on the top deck in the area just behind “the dog house,” the zone over the tractor fifth-wheel hitch and the drive wheels.
“That is $20-$30 variation in losses due to location in the trailer,” said Schaefer.
He said there may be several causes. It may have been due to the larger centrifugal force higher in the trailer resulting in the animals’ need to brace themselves. Or it could be from heat.
Work by Kettleswell and Mitchell has resulted in the addition of fans to livestock trailers across the EU.
“They fit them, that’s what the regs say you must do. Whether or not they use them or even have them wired up is another matter. Fans only run when the vehicle is parked. But we are finding that managing air flow during transit is just as important,” he said.
For poultry transport, air circulation and humidity control are critical and Kettleswell has developed a system that addresses some of those needs.
“For cattle or horses, the thought is they have to be pretty expensive to refit a trailer. But for a cost of ($35,000) for a vehicle that will run for 10 years or more, it actually far outweighs the losses due to stress,” he said.
Canadian packers report the highest percentage of dark cutting carcasses come during the extreme temperature fluctuations in spring and fall. Improved ventilation systems in trailers may reduce this problem, say the scientists.
Lowering stress during transport may be one way to improve meat quality and reduce fluid losses.
Adding amino acids to feed rations is an inexpensive method that would cost a few cents per day in the runup to shipping.
Schaefer said this feed addition showed a 7.8 percent improvement in grade at the packer.
Another method being examined is injecting or adding dexamethasone, a corticosteriod, to the animal before shipping. The effect seems to elevate stress levels in the animal, but not enough to hurt muscle tissue quality. The slightly elevated stress prior to shipping seems to aid in the prevention of a dramatic and sudden onset of stress.
Both drugs are already approved for use before slaughter.
“We know that the practice of slick bunks prior to shipping cattle produces more dark cutters than other feed-related practices (before shipment.)
Cutting off feed really induces a stress response. Here is an animal whose whole metabolism is turned all the way on and we just shut it off. That is really bad for meat quality,” Schaefer said.
