A bipartisan group of lawmakers is trying to stop the Defense Department from killing about 8,500 goats and pigs a year in medical training exercises designed to prepare troops for combat.

Rep. Hank Johnson, D-Ga., and Rep. Tom Marino, R-Pa., introduced a bill on Tuesday that would require the military to use only "human-based methods" to train service members to treat injuries sustained on the battlefield and end the use of "live tissue training," in which troops stab or shoot pigs and goats to simulate the treatment of combat trauma, by Oct. 1, 2020.

Johnson told the Washington Examiner he intends to raise the issue during debate on the fiscal 2018 National Defense Authorization Act and hopes to use the must-pass bill as a vehicle to ban live-tissue training. He said simulators offer better combat training than live animals, are more humane and are ultimately more cost-effective.

"It may cost more for a simulator than for a live animal in terms of initial outlay, but you can only use that animal once, you can use the simulator repeatedly. So over the course of time, it's better," he said.

The military already has transitioned many of its medical training courses to use human-based simulators, which advocates say are realistic and better prepare troops to handle combat injuries since the simulators have the same anatomy as a human. But for some training, the military continues to use live goats and pigs that are anesthetized, injured, treated and then euthanized.

The Defense Department is not onboard with completely ending its use of animals in combat trauma medical training – at least not yet. Lt. Col. Roger Cabiness, a department spokesman, said the military is "actively working to refine, reduce, and, when appropriate, replace the use of live animals in medical education and training.

"Therefore, we would ask Congress to work with us until there are validated alternatives, and that experience and confidence gained by current training methods in teaching life-saving procedures improve before they consider passing that legislation," Cabiness said.

The bill estimated that the Defense Department uses about 8,500 live animals a year, though People for the Ethical Treatment of Animals puts the number as high as 10,000 annually.

It's not the first time Johnson has introduced the bill in Congress, but it is the first time that it's been jointly introduced by a bipartisan team. The proposal also already had 35 cosponsors when it was introduced compared to just 26 in the last Congress, Johnson said.

Outside groups also believe the bipartisan support will give the effort a better chance this time.

"I believe it's been gaining momentum over the last few years," said Kathy Guillermo, a senior vice president at PETA. "We have released video tapes showing what goes on in these trainings, the simulators now are so sophisticated. … It's getting very difficult for the military to excuse stabbing and shooting pigs and goats."

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PETA will also be sending representatives to Capitol Hill to lobby for the bill, Guillermo said, and is "very hopeful" that a new administration and some new staff at the Pentagon will help the bill's passage.

However, Tom Spoehr, the director of the Center for National Defense at the Heritage Foundation, said he's not optimistic the bill will pass this year.

"This has been an agenda item for PETA and some physician groups since at least early '90s," Spoehr said. "I don't think it stands any reasonable change of being passed this year either."