A coalition of animal rights groups Tuesday petitioned USDA to limit the truck transport of animals to no more than 28 hours, as required by the federal “28-hour law.” The groups say that while 95 percent of all animals transported in the U.S. are shipped by truck, the USDA regulations implementing the law apply only to train transport.

The law, passed in 1873, generally requires that for every 28-hour confinement in interstate transport, animals must be allowed at least five hours of rest, during which time they are offloaded and given feed and water.

The groups filing the petition are the Humane Society of the United States, Farm Sanctuary, Compassion over Killing, and Animals’ Angels. They claim to represent “more than nine million members and constituents.”

Wayne Pacelle, president and CEO of the HSUS, criticized USDA for not enforcing the 28-hour law for truck transport, calling it “indefensible.” The group said “millions of animals” yearly are “transported for exceedingly long periods of time – up to 48 hours – while typically denied rest, food or even water.”

The groups also claim that USDA’s “failure to apply the Twenty-Eight Hour Law to truck transport also has significant” food safety implications. “The longer animals are confined…the greater the risk of spreading disease,” says the coalition.

PRNewswire, Livestock Marketing Association release